PDA

View Full Version : Custom Piston Operated M4 Project: Need Some Help & Have Some Questions


Hungarian_Legionnaire
10-16-2011, 2:59 PM
I was looking to build a "Custom"-as close as I can get to a USGI Mil-Spec M4, but with a Piston System. I looked at the Colt 6920 which is Mil-Spec & as I was told by Colt: "The uses the SAME Upper & Lower Receivers as the US Military Mil-Spec M4", just with different markings on the Lower" + of course it's Semiautomatic & has a 16.5" Barrel, in place of the 14" that is standard with most US Troops.

I would like to use a Hybrid of parts but using a Stripped Colt 6920 Lower & Upper, creating a completely Custom & unique Piston Operated Colt 6920, having the looks of a M4/6920 on the outside with with an H&K 416/ M556A1: Piston System/ Barrel, Complete Bolt Group, Tungsten Filled Buffer, H&K Buffer Spring ect. "Under The Hood" of the Upper. I know this is going to cost more than just straight out buying a H&K M556A1 or Colt 6920, but I am planning this out as a project, and IMO with a project you don't buy everything at once, (In a perfect scenario), I'll probably buy a number of the smaller less expensive parts once or twice a week & 1 of the more expensive parts once a month.

The thing is, I just don't know how much MORE this specific way of building the AR I want will be, compared to buying a complete off the shelf Colt 6920, then buying a complete H&K M556A1 Upper with Piston System, Barrel, Quadrail & every other part included. Just that H&K M556A1 Upper @ HKParts.net is like $2k! & a Colt 6920 is $1,000-$1,200. I'm glad still have my Aimpoint CompM2, that I had mounted on the long carryhandle of my FAMAS F-1 back when I was in Le Legion. Basically I don't have $3K+ to build a Custom Colt M4/6920 with a H&K Piston System, Bolt/Carrier ect. Which is why I planned for an extended Project, piece by piece.

I also Note: I have NO Experience with AR's, I've shot an actual M4 in Afghanistan because many of the US Operators loved the look of our FAMAS F-1's, & would always ask to shoot/ check them out, (As they should the FAMAS in general is a VERY reliable, versatile & accurate Bullpup due to it's 19.2" Barrel & Overall Length of 29.8", it's more compact than a M4A1 W/ the Stock Collapsed & has a Barrel that's just under an inch of the M16A4's 20" Barre)

I wanted to share my idea of MY ideal M4 Piston Project & would like any input or ideas to make my project faster & less costly. Thanks

Droppin Deuces
10-16-2011, 11:06 PM
So... Do you want something close to a mil spec M4 with a piston or do you want a Colt lower with an HK upper? Because there are a dozen or more ways to build the first thing, but only one way to build the second. And they aren't terribly similar.

Hungarian_Legionnaire
10-17-2011, 9:14 PM
So... Do you want something close to a mil spec M4 with a piston or do you want a Colt lower with an HK upper? Because there are a dozen or more ways to build the first thing, but only one way to build the second. And they aren't terribly similar.

I basically want the Piston System, Barrel & Internals ect. of the H&K M556A1 to be placed in to a Colt M4/6920 Striped Upper & build the Colt M4/6920 lower from a Stripped Colt Lower. How should I go about this ?

Hungarian_Legionnaire
10-18-2011, 9:07 AM
Bump!

wash
10-18-2011, 10:01 AM
So you want an AR that looks like a Colt but uses the HK piston system?

I hope you understand that building a rifle like that is all about looks because at best it will perform just like any other gas piston AR.

As far as looks go, I don't believe Colt uppers have any distinctive markings other than on the barrel and that is under the hand guard so making a look alike can be lots cheaper if you skip the hard to find name brand parts.

I'm not familiar with the HK piston system but if the Colt is direct impingement and has oval handguards, I think there is a gas piston system that uses the standard gas block and fits under the handguard (called an Osprey I think). If that's not the look you are going for, I would have to see pics before I can give a good answer.

Performance-wise, a 16.5" barrel with carbine gas and a gas piston system can certainly work but it's not going to do anything particularly well.

I don't get the fascination of Colt marked lowers or gas piston systems installed for looks but whatever floats your boat...

Droppin Deuces
10-18-2011, 10:10 AM
So you want an AR that looks like a Colt but uses the HK piston system?

I hope you understand that building a rifle like that is all about looks because at best it will perform just like any other gas piston AR.

As far as looks go, I don't believe Colt uppers have any distinctive markings other than on the barrel and that is under the hand guard so making a look alike can be lots cheaper if you skip the hard to find name brand parts.

I'm not familiar with the HK piston system but if the Colt is direct impingement and has oval handguards, I think there is a gas piston system that uses the standard gas block and fits under the handguard (called an Osprey I think). If that's not the look you are going for, I would have to see pics before I can give a good answer.

Performance-wise, a 16.5" barrel with carbine gas and a gas piston system can certainly work but it's not going to do anything particularly well.

I don't get the fascination of Colt marked lowers or gas piston systems installed for looks but whatever floats your boat...

Huh..?

wash
10-18-2011, 10:14 AM
What advantage would it have over a 16" mid-length with direct impingement?

The honest answer is probably none unless your idea of an advantage is not melting a gas tube in (barrel melting) full auto beta-mag dumps.

Droppin Deuces
10-18-2011, 10:18 AM
What advantage would it have over a 16" mid-length with direct impingement?

The honest answer is probably none unless your idea of an advantage is not melting a gas tube in (barrel melting) full auto beta-mag dumps.

But what won't it do particularly well?

wash
10-18-2011, 10:29 AM
Anything.

I'm not sure if you are just lacking in reading comprehension but when you say that something won't do anything particularly well, it usually means that it does things normally but does not display any abnormally good qualities.

That is the way I meant it.

wash
10-18-2011, 10:32 AM
You could also say an inexpensive Palmetto State Armory AR upper doesn't do anything particularly well and you would be 100% correct unless you count saving money as doing something particularly well.

Droppin Deuces
10-18-2011, 10:37 AM
What's with the attacks, son? It just sounds like your statement is based on an opinion. I'm just wondering what you've experienced to help you form that opinion.
I had a 16" carbine piston upper that could shoot right with my 16" target gun using the right ammo.

As for what a Palmetto State Armory upper is capable of, I can't and won't say since i've never used one.

Droppin Deuces
10-18-2011, 10:54 AM
I basically want the Piston System, Barrel & Internals ect. of the H&K M556A1 to be placed in to a Colt M4/6920 Striped Upper & build the Colt M4/6920 lower from a Stripped Colt Lower. How should I go about this ?

Not going to happen. I don't believe your parts are going to be compatible. Even if they were, your modified upper would just end-up looking like an HK upper, so why not just have an HK upper?

wash
10-18-2011, 11:00 AM
So you're saying that a rifle with a 16" barrel and a carbine length gas system is always going to be super accurate?

In my opinion the gun in your example was accurate despite the carbine length gas piston system, not because of it.

The higher gas pressure, increased dwell time and mass of the new moving parts in a carbine length gas piston system all lead to additional movement of the gun before the bullet leaves the barrel and that will have a negative impact on accuracy.

You don't see gas piston ARs in long range rifle matches because there is no accuracy advantage to a gas piston.

Gas piston systems might have an advantage in reliability but on a 16" barrel a mid-length system would operate at lower pressures for reduced carrier speeds and it will just generally be smoother and that should give you a theoretical advantage in reliability.

So it's not really optimized for either...

It still could be fantastically accurate and Rolex reliable but it won't be because it has a 16.5" barrel with a carbine length gas piston system.

It will most likely shoot close enough to any other direct impingement Colt with good enough reliability that you'll never see a difference.

If he builds what he describes, I expect the performance to be exceedingly normal.

I can't put it any more plainly.

Droppin Deuces
10-18-2011, 11:02 AM
So you're saying that a rifle with a 16" barrel and a carbine length gas system is always going to be super accurate?

In my opinion the gun in your example was accurate despite the carbine length gas piston system, not because of it.

The higher gas pressure, increased dwell time and mass of the new moving parts in a carbine length gas piston system all lead to additional movement of the gun before the bullet leaves the barrel and that will have a negative impact on accuracy.

You don't see gas piston ARs in long range rifle matches because there is no accuracy advantage to a gas piston.

Gas piston systems might have an advantage in reliability but on a 16" barrel a mid-length system would operate at lower pressures for reduced carrier speeds and it will just generally be smoother and that should give you a theoretical advantage in reliability.

So it's not really optimized for either...

It still could be fantastically accurate and Rolex reliable but it won't be because it has a 16.5" barrel with a carbine length gas piston system.

It will most likely shoot close enough to any other direct impingement Colt with good enough reliability that you'll never see a difference.

If he builds what he describes, I expect the performance to be exceedingly normal.

I can put it any more plainly.

So basically, you read it on the internet. That's what I figured.

wash
10-18-2011, 11:20 AM
No, I have shot and assembled rifle length, mid-length, carbine length and pistol length gas system ARs and I've messed around with a few gas piston systems too (both AR and FAL).

I haven't seen too many good reasons to change an AR to gas piston. One good reason is if you have a 5.45*39 AR and want to keep the corrosive gasses out of your bolt carrier. I think they might be better on some supressed rifles but I'm not sure about that (I haven't played with supressors).

Now why don't you tell me what gas piston systems do better than direct impingement if I'm so wrong about this?

Nathan Krynn
10-18-2011, 11:35 AM
Guys you are both good people, lets not get personal here. It is not helping especially if this gets into another piston vs DGI argument.

OP seriously you are heading down a dark road. You wont know that upper was a colt and it would have to be modified anyway for the piston. Plus I highly doubt Colt makes the upper itself, everyone out sources on the AR-15 and Colt started that I am pretty sure.

They were once upon a time the $#*% for AR-15's just like 1911's but this may be my opinion but Colt is a four letter word to me now. They have gone down hill since there prime and there are much better companies IMHO now a days. A lot of the Colts I have seen lately have been not the greatest, I saw one the other week that was a rattle trap. Just like if I wanted a brand new 1911 I would not chose Colt.

I would just get another piston rifle or upper and put on your Colt lower if you demand the roll mark.

Hungarian_Legionnaire
10-18-2011, 1:36 PM
So you want an AR that looks like a Colt but uses the HK piston system?

I hope you understand that building a rifle like that is all about looks because at best it will perform just like any other gas piston AR.

As far as looks go, I don't believe Colt uppers have any distinctive markings other than on the barrel and that is under the hand guard so making a look alike can be lots cheaper if you skip the hard to find name brand parts.

I'm not familiar with the HK piston system but if the Colt is direct impingement and has oval handguards, I think there is a gas piston system that uses the standard gas block and fits under the handguard (called an Osprey I think). If that's not the look you are going for, I would have to see pics before I can give a good answer.

Performance-wise, a 16.5" barrel with carbine gas and a gas piston system can certainly work but it's not going to do anything particularly well.

I don't get the fascination of Colt marked lowers or gas piston systems installed for looks but whatever floats your boat...

Other than The H&K 416 having a tapering Bore that H&K claims is suppose to increase accuracy, I expect nothing more or less than a Match Grade AR 1.5"-2"MOA (Depending On Optics Configuration).

Since I will be building this up from ONLY the Stripped Colt Upper & Lower Receivers I won't have or will be using the standard 6920 Quadrail, or standard Handguard. I have herd of the retro-fit Osprey Defense Gas Piston Retrofit Conversion Kit, but from what I've herd the best Piston Systems are The H&K 416/M556A1 as well as the LWRC M6.

Knowing from 1st hand Combat Experience, there is a VAST difference between a DI, dirty fouling in the Receiver, Bolt & Trigger Group, when compared to a Piston System I've been Joint Ops with 1st Recon & SEALs the 3-4 times we ran Ops rather in the day or night, they would use the best AK74's, AKS-74U/ krinkovs & AK47's W/ Side or Under Folding Stocks whal their DI M4A1's were in the back of the Humvee, why do we as Elite Operators choose 19th Century firearms over new 21st Century M16A4's & M4A1's ?

What it will do more than exceptionally well is keep HOT GASSES, CARBON FOULING & UN-BURNT Powder out of the Receiver, Note: The H&K 416 video on Futureweapons, MAC Shoots 250-300 rounds threw a DI and lights a match off the gas tube, same thing with the piston system he IMMEDIATELY finishes shooting full auto pops out the rear pin and holds the bolt & carrier in his bare hand. That's Exceptionally well. I just don't like the weight of the H&K M556A1 & Want a Colt Mil Spec Upper & Lower as they are the same Upper & Lowe used for U.S Military Service But sold to Civi's with only a difference in stamping, so I would have one of the BEST Piston Driven Semi-auto M4's, & I already have all the H&K Parts, a Match CMC Tactical AR-15 Trigger, Knight Armament SOPMOD Free Floating Quadrail, LMT SOPMOD Stock, Magpul MIAD Pistol Grip & a set of Front & rear Troy Industries Folding Battlesights... & A Stripped 6920 Upper is like I said prior the same as the Mil Spec U.S M4A1 just for civi's, with the upper & Lower the only difference between the 6920 and an M4A1 is what is says on the side of the Lower + It's not Auto.

Hungarian_Legionnaire
10-18-2011, 1:49 PM
Not going to happen. I don't believe your parts are going to be compatible. Even if they were, your modified upper would just end-up looking like an HK upper, so why not just have an HK upper?

How & what way would it look like an H&K upper ? I'm using a Colt M4/ 6920 Upper,SOPMOD Knight Armament Quad Rail the ONLY think showing would be the H&K Barrel & the Right Side of the H&K Bolt has a small "HK" Logo, unless someone were to know exactly what an H&K Barrel looked like, or noticed the little "HK" logo everything is INSIDE the Colt Upper except the barrel. + The H&K M556A1 is too heavy it's rail system and thick receiver make it weigh 8+lbs unloaded. So what on this set up would make it look anything like the H&K 416/ M556A1? ALL COLT on the outside with a H&K Barrel ? That makes NO Since.

starsnuffer
10-18-2011, 1:53 PM
HK is the better gas piston system because it's a system, not a bolt on replacement for a DI system. It's not going to work on a colt, or any other standard AR upper receiver. The height of the receiver is different (hence why the sights are different heights), and the way the barrel mounts to the receiver is different then a standard AR (if there is such a thing for a standard in an AR).

Just get a MR556, you can put all that afternarket crap on the lower and replace the stock. You can even put on the troy sights, although the sight picture will be higher due to the rail being higher (you can get the troy micro sights that are designed for the HK). You can also just put a MR556 upper on any standard AR lower, including a Colt (though getting a colt lower in California is a problem).

Or you can just draw up your dream rifle in autocad and pay a machine shop 20k or so to make it for you.

-W

starsnuffer
10-18-2011, 1:55 PM
BTW the rail on the MR556 is very very light. The fact that the barrel is a bull barrel (same profile as the IAR) is what make it front heavy. It's a full inch in diameter up to the piston block, and .78 inches from block to muzzle. You can reprofile the barrel if you want it to be lighter.

-W

Nathan Krynn
10-18-2011, 1:57 PM
It is ultimately your rifle and what ever brings you enjoyment is great.

My only real question is why does it have to be a colt upper and lower. I understand you are a soldier and the Colt M4 is what you are used too and rely upon. But Colt lowers tend to be sloppy and the uppers I doubt they make it at all. You can get an OLL that is made much better for much less and an upper from 50 other places that most likely is the same ones colt uses for much less.

EDIT: or do what starsnuffer said would be better IMHO.

Pryde
10-18-2011, 2:11 PM
What you want is not possible.

The stripped upper receiver of a H&K is a few millimeters taller than a Colt upper to allow for clearance of the added height for the gas piston, the HK internals will not fit into a Colt upper. In addition I do not think the H&K barrel can fit anything over it other than the H&K rail due also to the extra height of the piston assembly. The closest thing to achieving what you want is to buy an HK upper to put on a Colt lower.

I'm surprised that nobody here knew this......

wash
10-18-2011, 3:13 PM
If you have all the parts, what is stopping you?

Pryde
10-18-2011, 5:11 PM
If you have all the parts, what is stopping you?

The fact that it is mechanically impossible maybe?

Inquirer
10-18-2011, 6:44 PM
Other than The H&K 416 having a tapering Bore that H&K claims is suppose to increase accuracy, I expect nothing more or less than a Match Grade AR 1.5"-2"MOA (Depending On Optics Configuration).

Since I will be building this up from ONLY the Stripped Colt Upper & Lower Receivers I won't have or will be using the standard 6920 Quadrail, or standard Handguard. I have herd of the retro-fit Osprey Defense Gas Piston Retrofit Conversion Kit, but from what I've herd the best Piston Systems are The H&K 416/M556A1 as well as the LWRC M6.

Knowing from 1st hand Combat Experience, there is a VAST difference between a DI, dirty fouling in the Receiver, Bolt & Trigger Group, when compared to a Piston System I've been Joint Ops with 1st Recon & SEALs the 3-4 times we ran Ops rather in the day or night, they would use the best AK74's, AKS-74U/ krinkovs & AK47's W/ Side or Under Folding Stocks whal their DI M4A1's were in the back of the Humvee, why do we as Elite Operators choose 19th Century firearms over new 21st Century M16A4's & M4A1's ?

What it will do more than exceptionally well is keep HOT GASSES, CARBON FOULING & UN-BURNT Powder out of the Receiver, Note: The H&K 416 video on Futureweapons, MAC Shoots 250-300 rounds threw a DI and lights a match off the gas tube, same thing with the piston system he IMMEDIATELY finishes shooting full auto pops out the rear pin and holds the bolt & carrier in his bare hand. That's Exceptionally well. I just don't like the weight of the H&K M556A1 & Want a Colt Mil Spec Upper & Lower as they are the same Upper & Lowe used for U.S Military Service But sold to Civi's with only a difference in stamping, so I would have one of the BEST Piston Driven Semi-auto M4's, & I already have all the H&K Parts, a Match CMC Tactical AR-15 Trigger, Knight Armament SOPMOD Free Floating Quadrail, LMT SOPMOD Stock, Magpul MIAD Pistol Grip & a set of Front & rear Troy Industries Folding Battlesights... & A Stripped 6920 Upper is like I said prior the same as the Mil Spec U.S M4A1 just for civi's, with the upper & Lower the only difference between the 6920 and an M4A1 is what is says on the side of the Lower + It's not Auto.

Hungarian Legionnaire - you're awesome, dude. I admire how fiercely you're sticking to your plan. From the research I've done, the best piston systems right now are coming out of LWRC and PWS. Their uppers are basically the cost of a rifle, but they might be closer to what you want. I also don't know how they compare to the Colt offerings, but if you're handy and you're willing to spend, it may be worth it to get a PWS upper, strip the piston system from it, and install it in your Colt and KAC externals. Just a thought; don't know how you feel about that kind of overhead. But I like your project, best of luck on it!

--Inq

Hungarian_Legionnaire
10-18-2011, 11:45 PM
What you want is not possible.

The stripped upper receiver of a H&K is a few millimeters taller than a Colt upper to allow for clearance of the added height for the gas piston, the HK internals will not fit into a Colt upper. In addition I do not think the H&K barrel can fit anything over it other than the H&K rail due also to the extra height of the piston assembly. The closest thing to achieving what you want is to buy an HK upper to put on a Colt lower.

I'm surprised that nobody here knew this......

I'm not a gun smith, but I spoke to both Colt & H&K BEFORE ordering the H&K Barrel, Piston System Action ect. & I was told by [b]BOTH[b/] Colt & H&K That the parts are compatible to fit in to a Colt M4, the US Military was talking about using H&K's Piston System to Retro-Fit all of their M4's, IDK if that is still going to happen but from what both companies say I will have NO problem at all Installing my H&K Piston System in to the Colt 6920 Upper.

Hungarian_Legionnaire
10-18-2011, 11:46 PM
The fact that it is mechanically impossible maybe?

How so ?

Hungarian_Legionnaire
10-18-2011, 11:48 PM
If you have all the parts, what is stopping you? I DON'T nor did I EVER say I had all of the parts, I still need some small parts + The Main pats to build a AR, it's called the Upper & Lower Receivers...

Hungarian_Legionnaire
10-19-2011, 12:07 AM
Hungarian Legionnaire - you're awesome, dude. I admire how fiercely you're sticking to your plan. From the research I've done, the best piston systems right now are coming out of LWRC and PWS. Their uppers are basically the cost of a rifle, but they might be closer to what you want. I also don't know how they compare to the Colt offerings, but if you're handy and you're willing to spend, it may be worth it to get a PWS upper, strip the piston system from it, and install it in your Colt and KAC externals. Just a thought; don't know how you feel about that kind of overhead. But I like your project, best of luck on it!

--Inq

Thanks Man, finally someone who appreciates what is going to be an AMAZING Piston Operated M4. Made from the Tire 1 of AR parts, I'll be sure to keep you up-todate on the project, once I get things going I'm going to start a Colt M4/6920 Piston Operated Step-By-Step Thread With HD Pics! I can't wait to start the build... So you have herd that the LWRC Piston like out of the M6 is better than that of the H&K 416/ M556A1's Piston System, & I'm really sticking to the Colt M4/M556A1 Upper & Lower or were you saying to buy the Upper then Piece it out ? What would you, considering your an AR-Piston-guy, what would you recommend ? LWRC: Barrel, Piston System, Action ect. or the PWS: Barrel, Piston System, Action ect. The H&K M556A1 is $2,000 JUST for a complete upper! That's more than the $1,200 ENTIRE Colt 6920! I'm just trying how to find how to get this done for the least amount of money, as soon as possible with the best of the best in Parts Quality. Really Appreciate the comment man :thumbsup:

Hungarian_Legionnaire
10-19-2011, 12:28 AM
It is ultimately your rifle and what ever brings you enjoyment is great.

My only real question is why does it have to be a colt upper and lower. I understand you are a soldier and the Colt M4 is what you are used too and rely upon. But Colt lowers tend to be sloppy and the uppers I doubt they make it at all. You can get an OLL that is made much better for much less and an upper from 50 other places that most likely is the same ones colt uses for much less.

EDIT: or do what starsnuffer said would be better IMHO.

As I said in the description: "Note: I have NO Experience with AR's, I've shot an actual M4 in Afghanistan because many of the US Operators loved the look of our FAMAS F-1's, & would always ask to shoot/ check them out." I'm a Legionnaire NOT a Soldier, sorry if that wasn't clear, I want a M4/6920 Upper & Lower because growing up in Europe (Szombathely, Hungary, to be specific) Colt WAS & Still is "The Bee's Knees", as in Tire 1, and made to exceed Mil Spec requirements, have a great coating & have been used since Vietnam to this day by Special Forces across the world. What Upper & Lower that is Mil Spec M4 would you recommend ? It's a pain to get the Colt, I have to specially order the Upper & Lower from Colt's Mil Department.

Hungarian_Legionnaire
10-19-2011, 12:31 AM
BTW the rail on the MR556 is very very light. The fact that the barrel is a bull barrel (same profile as the IAR) is what make it front heavy. It's a full inch in diameter up to the piston block, and .78 inches from block to muzzle. You can reprofile the barrel if you want it to be lighter.

-W

Is it a "Bull Barrel" ? H&K simply said it it just had a Tapering Bore for Enhanced Accuracy.

Hungarian_Legionnaire
10-19-2011, 12:57 AM
HK is the better gas piston system because it's a system, not a bolt on replacement for a DI system. It's not going to work on a colt, or any other standard AR upper receiver. The height of the receiver is different (hence why the sights are different heights), and the way the barrel mounts to the receiver is different then a standard AR (if there is such a thing for a standard in an AR).

Just get a MR556, you can put all that afternarket crap on the lower and replace the stock. You can even put on the troy sights, although the sight picture will be higher due to the rail being higher (you can get the troy micro sights that are designed for the HK). You can also just put a MR556 upper on any standard AR lower, including a Colt (though getting a colt lower in California is a problem).

Or you can just draw up your dream rifle in autocad and pay a machine shop 20k or so to make it for you.

-W

I'm not a gun smith, but I spoke to both Colt & H&K BEFORE ordering the H&K Barrel, Piston System Action ect. & I was told by [b]BOTH[b/] Colt & H&K That the parts are compatible to fit in to a Colt M4, the US Military was talking about using H&K's Piston System to Retro-Fit all of their M4's, IDK if that is still going to happen but from what both companies say I will have NO problem at all Installing my H&K Piston System in to the Colt 6920 Upper.
Mounting of the M556A1 Barrel is the same as mounting it to any other AR Upper. If BOTH Companies are lying to a Ret. Legionnaire as well as a 1st Recon Marine who I meet at Camp Lemonier, Djibouti, Horn of Africa I've had this idea for over 3 years, and Asked my friend to Send me a Colt/ H&K Catalog when he got back to the states, & I wrote him asking him to call and ask the same question before I returned to the states.

Why would a Colt Lower be any different than any other AR in CA with a RaddLock/BulletButton & 10rd Magazines it's the same as ANY Other Lower, if I'm able to buy a complete Colt 6920 in CA, why wouldn't I be able to buy the part that isn't even registered ? Makes No Since at all.

starsnuffer
10-19-2011, 7:03 AM
HL,

You're on the right track but a bit confused, I think.

The MR556/HK416 upper receiver, will fit on a colt lower receiver, or any other AR lower receiver. When HK and the US military speak of retrofitting their M4's with the 416 system, that is what they mean, complete replacement of the upper receiver. It's just a matter of pulling out the two takedown pins, throwing away the old receiver (barrel, BCG, handguard and all), and pinning on the new HK receiver. It's so easy a Marine could do it.

Where you are getting confused is thinking that the "guts" of the HK can be removed from the receiver and replaced inside a non-HK receiver. That is a no go, they will not fit, will not work, and the designs are not compatible.

I hope that clears that part up for you.

As for the Colt lower being different then any other lower in California, please see the flowchart. Particular rifles are banned BY NAME in California, Colt being one of them. This is why you hear the term "OLL", or Off List Lower. Yes, mechanically they are the same thing (it's just a stamped/milled/forged piece of metal after all), but legally they are different. It's stupid, it sucks, but that's the law.

Hope that helps, good luck!

starsnuffer
10-19-2011, 7:07 AM
Is it a "Bull Barrel" ? H&K simply said it it just had a Tapering Bore for Enhanced Accuracy.

The inside of the bore is tapered for accuracy. The outside is a bull barrel, meaning that it is as close as they can get to a solid hunk of unprofiled steel.

This is a good thing, because it means that the end user can reprofile the barrel as he sees fit. It's way easier to remove metal then add metal.

Here's a pic of what Jason with IGF is doing with them, this one is standard M4 profile (with an extended FH to meet the 16" legal requirement):

http://investmentgradefirearms.com/images/services/mr556_m4.jpg

-W

Q
10-19-2011, 7:21 AM
^Yourz? I spie a bb on it.:detective: Barrel work looks good. I'm hoping to get a bayo lug for mine for a IAR clone.

I'd just go with a standard AR. The pro is you can use a 22lr kit in it. :D
The only two piston ones I'd get are HK and LWRC.

starsnuffer
10-19-2011, 7:33 AM
Nope, not mine. I haven't touched the barrel on mine yet, lugging it around is turning me into a manly man!

I have something like this in mind, only 14.5 inches with the area in front of the block to the muzzle fluted with a battlecomp 1.5 pinned:

http://www.hkbeltfed.com/mr1.jpg

-W

Hungarian_Legionnaire
10-19-2011, 8:45 AM
HL,

You're on the right track but a bit confused, I think.

The MR556/HK416 upper receiver, will fit on a colt lower receiver, or any other AR lower receiver. When HK and the US military speak of retrofitting their M4's with the 416 system, that is what they mean, complete replacement of the upper receiver. It's just a matter of pulling out the two takedown pins, throwing away the old receiver (barrel, BCG, handguard and all), and pinning on the new HK receiver. It's so easy a Marine could do it.

Where you are getting confused is thinking that the "guts" of the HK can be removed from the receiver and replaced inside a non-HK receiver. That is a no go, they will not fit, will not work, and the designs are not compatible.

I hope that clears that part up for you.

As for the Colt lower being different then any other lower in California, please see the flowchart. Particular rifles are banned BY NAME in California, Colt being one of them. This is why you hear the term "OLL", or Off List Lower. Yes, mechanically they are the same thing (it's just a stamped/milled/forged piece of metal after all), but legally they are different. It's stupid, it sucks, but that's the law.

Hope that helps, good luck!

Thanks for the help, but keep in mind that I have Earned the Tittle & Honor to be called a "Legionnaire", which is of course an Elite Military Operations Regiment. I don't need to be told what "take down pins" do, I am Very Aware how an M4/ M16 is taken apart for being made poorly for years with the unreliable DI system, Instead of a Piston System for a cleaner, Cooler Receiver. When I mentioned the H&K 416 Piston System Retro-Fit, I never said it would be with the Gas Block, Piston System, Action ect. Not the entire H&K 416 Upper that would add 1.5-2 Lbs to the M4 & be extremely Expensive, I'm not apart of the U.S Mil or DOD but getting a upper receiver that costs 2x what the complete DI M4 costs would be ridiculous. Even with the discount they would get for buying in bulk it would still be too much, the Barrels aren't Chrome Lined, thus they wear out faster... I never herd of a complete H&K Upper Replacement, just what is needed for the Armorer to fit the piston systems on. & I forgot who said that the H&K 416 Upper doesn't fit any other AR, & Is basically propriety is lacking a few chromosomes (Mentally "Special")
As for the "OLL" There is a SP6920 Stripped Lower for Sale on Gunbroker for $250 & It's CA Legal... Maybe because it's called the "Spotter" and Not the "Law Enforcement" ?

wash
10-19-2011, 9:22 AM
You can buy a ~$300 gas piston retrofit kit that will fit a Colt upper. Adams arms makes that.

If you want LWRC, you need to buy a whole upper because I don't think they sell the individual parts.

Same story for PWS, you have to buy the upper.

That Osprey kit will let you use almost everything from the COLT.

From what I'm hearing here, the HK gas piston system won't even fit.

Most of the gas piston systems were designed as a retrofit so that the manufacturers did not have to tool up to make a new upper receiver. They have the gas piston running through a Bushing where the gas tube normally goes.

If the HK used a taller upper receiver with the gas piston raised, it just won't line up right with a Colt upper.

That's kind of an advantage for direct impingement, gas tubes can bend wherever you want them to go, pistons have to move in straight lines and angles don't work out so well.

Colt and HK might have told you that the parts are compatible but they might not have understood the question.

If what you want to do was plug and play, someone would have tried it already.

What you can do to easily tell if this can be done is measure the distance between the bore centerline and gas piston centerline on the HK gas block, then measure the distance between the bore centerline and the gas tube centerline at the front of your Colt upper receiver. If the measurements differ by more than a few thousandths of an inch, it's not going to be plug and play.

Nathan Krynn
10-19-2011, 10:49 AM
Thanks for the help, but keep in mind that I have Earned the Tittle & Honor to be called a "Legionnaire", which is of course an Elite Military Operations Regiment. I don't need to be told what "take down pins" do, I am Very Aware how an M4/ M16 is taken apart for being made poorly for years with the unreliable DI system, Instead of a Piston System for a cleaner, Cooler Receiver. When I mentioned the H&K 416 Piston System Retro-Fit, I never said it would be with the Gas Block, Piston System, Action ect. Not the entire H&K 416 Upper that would add 1.5-2 Lbs to the M4 & be extremely Expensive, I'm not apart of the U.S Mil or DOD but getting a upper receiver that costs 2x what the complete DI M4 costs would be ridiculous. Even with the discount they would get for buying in bulk it would still be too much, the Barrels aren't Chrome Lined, thus they wear out faster... I never herd of a complete H&K Upper Replacement, just what is needed for the Armorer to fit the piston systems on. & I forgot who said that the H&K 416 Upper doesn't fit any other AR, & Is basically propriety is lacking a few chromosomes (Mentally "Special")
As for the "OLL" There is a SP6920 Stripped Lower for Sale on Gunbroker for $250 & It's CA Legal... Maybe because it's called the "Spotter" and Not the "Law Enforcement" ?

Your experiences are of course different then mine.

However the "made poorly for years with the unreliable DI system" is mostly an internet myth. Properly lubed (not even necessarily cleaned) will run for many thousands of rounds. I don't clean mine for 500-1k rounds really, not saying I should or recommend it. I have run DI since I was 18 in all most every environment HARD and rarely had a problem, when I did it was the mag most of the time. Hot gas blowing into the receiver like you know is part of the design but its not poor, it has much less moving parts which was the innovative part of the design.

Also most of the SF guys I know pick up AK folders for the shorter OAL which helps in a humvee and the fact the 7.62x39 chews cover much better then a 5.56. Also then they don't have to adhere to the standard ammo allotment.

Hungarian_Legionnaire
10-19-2011, 5:04 PM
Your experiences are of course different then mine.

However the "made poorly for years with the unreliable DI system" is mostly an internet myth. Properly lubed (not even necessarily cleaned) will run for many thousands of rounds. I don't clean mine for 500-1k rounds really, not saying I should or recommend it. I have run DI since I was 18 in all most every environment HARD and rarely had a problem, when I did it was the mag most of the time. Hot gas blowing into the receiver like you know is part of the design but its not poor, it has much less moving parts which was the innovative part of the design.

Also most of the SF guys I know pick up AK folders for the shorter OAL which helps in a humvee and the fact the 7.62x39 chews cover much better then a 5.56. Also then they don't have to adhere to the standard ammo allotment.

Have ANY of your DI AR's seen combat ? When I was in Afghanistan on many Joint Operations with US Spec Ops, I've herd MANY complaints of their DI M4's, M16's & how much they had to clean them because of the DI System, they DEFIANTLY didn't use the AK Variants because of it's length an M4A1 is SHORTER than an AK47/74 with a Non-Folding Stock, they used them because they could pick up a good or decent one clean it ONCE & Never clean/ oil it again, a 1st Recon Marine said he had his for going on 12 months, having cleaned & oiled it, function tested it and said "The only problem I've had with this AK is having the Pistol Grip come loose, and ummm Running out of Ammo?, hah nothing Frenchie" He called me "Frenchie" trying to make fun of the fact I was in the French Foreign Legion, it was a joke.

But I can't do any of the measurements because like I've said to many people [b]I DO NOT HAVE THE UPPER OR LOWER RECEIVERS YET[b/]

Thank you for your reply, but I DO In Fact know how a DI system, as well as how a Piston System Work, I don't need to be told how a DI system works, I know how it works and am building a "Custom M4/ Piston System" BECAUSE I want an AR, with out (IMO it's SH*TTY) DI System, If you or anyone else love Hot Gasses & Carbon Fouling/ Unburnt Powder being Blown Back in to the Receiver that's awesome.

I am as I've stated before a Veteran Of The French Foreign Legion, & have had many Joint Operations with US Special Operators & have seen the Many Issues & FU*K-Up's In Combat, Where US Operators have to transfer from their DI M4 to an Op For AK, The U.S Needs to Sort Out Their Standard Issue Assault Rifle, I Have PERSONALLY Seen 2 Operators Get Shot & Thankfully Live, AFTER The Failure of What Their County (The U.S) Issues Them. From What I've Seen, I KNOW There Have Been Soldiers, Marines, Spec Ops Who Have Been KILLED Because Of This. It's Mass Manslaughter IMO.

I know civi's don't use their DI AR's to the extent of Soldiers & Spec Ops do, even if they go to 3 gun matches, and go to carbine classes and run their DI AR's hard.

I Just personally will not run a DI System, or a Adams Arms or Osprey Defense Gas Piston Retrofit Conversion Kit, Regardless If I have to buy a New complete upper that's made as a SYSTEM for that Barrel & Action, then part it out.

Hungarian_Legionnaire
10-19-2011, 5:11 PM
HL,

You're on the right track but a bit confused, I think.

The MR556/HK416 upper receiver, will fit on a colt lower receiver, or any other AR lower receiver. When HK and the US military speak of retrofitting their M4's with the 416 system, that is what they mean, complete replacement of the upper receiver. It's just a matter of pulling out the two takedown pins, throwing away the old receiver (barrel, BCG, handguard and all), and pinning on the new HK receiver. It's so easy a Marine could do it.

Where you are getting confused is thinking that the "guts" of the HK can be removed from the receiver and replaced inside a non-HK receiver. That is a no go, they will not fit, will not work, and the designs are not compatible.

I hope that clears that part up for you.

As for the Colt lower being different then any other lower in California, please see the flowchart. Particular rifles are banned BY NAME in California, Colt being one of them. This is why you hear the term "OLL", or Off List Lower. Yes, mechanically they are the same thing (it's just a stamped/milled/forged piece of metal after all), but legally they are different. It's stupid, it sucks, but that's the law.

Hope that helps, good luck!

Ok, if the H&K M556A1 Gas System & Action I've already Actually wont fit in a Colt M4/6920 then will LWRC's M6: Barrel & Piston System fit ? I Really wanted to run the H&K Piston System, but if they and Colt Both made/Lied to me and a Marine that it's Barrel & Piston System Will in fact fit in to the M4/6920 Upper, then I will have to return what I have purchased, Because I am intent on using the Colt M4/6920 Upper & Lower.

Hungarian_Legionnaire
10-19-2011, 5:14 PM
You can buy a ~$300 gas piston retrofit kit that will fit a Colt upper. Adams arms makes that.

If you want LWRC, you need to buy a whole upper because I don't think they sell the individual parts.

Same story for PWS, you have to buy the upper.

That Osprey kit will let you use almost everything from the COLT.

From what I'm hearing here, the HK gas piston system won't even fit.

Most of the gas piston systems were designed as a retrofit so that the manufacturers did not have to tool up to make a new upper receiver. They have the gas piston running through a Bushing where the gas tube normally goes.

If the HK used a taller upper receiver with the gas piston raised, it just won't line up right with a Colt upper.

That's kind of an advantage for direct impingement, gas tubes can bend wherever you want them to go, pistons have to move in straight lines and angles don't work out so well.

Colt and HK might have told you that the parts are compatible but they might not have understood the question.

If what you want to do was plug and play, someone would have tried it already.

What you can do to easily tell if this can be done is measure the distance between the bore centerline and gas piston centerline on the HK gas block, then measure the distance between the bore centerline and the gas tube centerline at the front of your Colt upper receiver. If the measurements differ by more than a few thousandths of an inch, it's not going to be plug and play.

Have ANY of your DI AR's seen combat ? When I was in Afghanistan on many Joint Operations with US Spec Ops, I've herd MANY complaints of their DI M4's, M16's & how much they had to clean them because of the DI System, they DEFIANTLY didn't use the AK Variants because of it's length an M4A1 is SHORTER than an AK47/74 with a Non-Folding Stock, they used them because they could pick up a good or decent one clean it ONCE & Never clean/ oil it again, a 1st Recon Marine said he had his for going on 12 months, having cleaned & oiled it, function tested it and said "The only problem I've had with this AK is having the Pistol Grip come loose, and ummm Running out of Ammo?, hah nothing Frenchie" He called me "Frenchie" trying to make fun of the fact I was in the French Foreign Legion, it was a joke.

But I can't do any of the measurements because like I've said to many people I DO NOT HAVE THE UPPER OR LOWER RECEIVERS YET

Thank you for your reply, but I DO In Fact know how a DI system, as well as how a Piston System Work, I don't need to be told how a DI system works, I know how it works and am building a "Custom M4/ Piston System" BECAUSE I want an AR, with out (IMO it's SH*TTY) DI System, If you or anyone else love Hot Gasses & Carbon Fouling/ Unburnt Powder being Blown Back in to the Receiver that's awesome.

I am as I've stated before a Veteran Of The French Foreign Legion, & have had many Joint Operations with US Special Operators & have seen the Many Issues & FU*K-Up's In Combat, Where US Operators have to transfer from their DI M4 to an Op For AK, The U.S Needs to Sort Out Their Standard Issue Assault Rifle, I Have PERSONALLY Seen 2 Operators Get Shot & Thankfully Live, AFTER The Failure of What Their County (The U.S) Issues Them. From What I've Seen, I KNOW There Have Been Soldiers, Marines, Spec Ops Who Have Been KILLED Because Of This. It's Mass Manslaughter IMO.

I know civi's don't use their DI AR's to the extent of Soldiers & Spec Ops do, even if they go to 3 gun matches, and go to carbine classes and run their DI AR's hard.

I Just personally will not run a DI System, or a Adams Arms or Osprey Defense Gas Piston Retrofit Conversion Kit, Regardless If I have to buy a New complete upper that's made as a SYSTEM for that Barrel & Action, then part it out.