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View Full Version : Ran a 9mm buffer in my new M4 today, ran like a champ!


missiontrails
09-30-2009, 11:26 AM
I bought a 5.2oz Colt 9mm buffer for my newest CMMG 14.5" M4. This is the first time I have fired this rifle. Today I ran 100 rounds of Federal XM193, 20 rounds of PMC Bronze .223, and 20 rounds of Sellier & Bellot .223. I warmed up the rifle with the Federal first, then I ran the .223 stuff in 5 round sessions, just to see if the bolt would lock back after the last round was fired each time.

NO FTF
NO FTE
All rounds went bang.
Bolt locked back after last shot with ALL ammo.

The rifle felt soft as far as recoil is concerned. No "sproing" sound from the buffer spring either. Great day.

reidnez
09-30-2009, 11:47 AM
Hey, if it works...go with it!

CHS
09-30-2009, 11:49 AM
So.... What problem was it that you fixed with the 9mm buffer?

thedrickel
09-30-2009, 11:58 AM
So.... What problem was it that you fixed with the 9mm buffer?

The sproing!

djleisure
09-30-2009, 12:27 PM
I love the sproing! No sproing is like making love to a mute!

missiontrails
09-30-2009, 12:28 PM
So.... What problem was it that you fixed with the 9mm buffer?

Less recoil, less trauma to the internal parts over the long haul.

slappomatt
09-30-2009, 12:35 PM
Less recoil, less trauma to the internal parts over the long haul.

while the trauma to internal parts is debatable you have heavier STEEL parts banging around inside the action doesnt seem like less trauma to me. (although it is a slower speed)

I run one in my gun as well as a Larue extra power spring. with that and the comp the gun shoots like a 22LR. I have yet to have a single issue after several 100's of rounds.

There are people who say if the stock stuff works then just use that. well why dont you put 155-75-14" tires on your car and drive it around. Just because it works doesnt mean it works well.

Haters!! lol.

missiontrails
09-30-2009, 12:48 PM
while the trauma to internal parts is debatable you have heavier STEEL parts banging around inside the action doesnt seem like less trauma to me. (although it is a slower speed)

I run one in my gun as well as a Larue extra power spring. with that and the comp the gun shoots like a 22LR. I have yet to have a single issue after several 100's of rounds.

There are people who say if the stock stuff works then just use that. well why dont you put 155-75-14" tires on your car and drive it around. Just because it works doesnt mean it works well.

Haters!! lol.
Concur. Equipment hits the back of the receiver extension with less force. Mainly do it to change the feel my rifles. NO sproing sound either.

reidnez
09-30-2009, 12:58 PM
But the "sproing" tells you when you're empty ;)

missiontrails
09-30-2009, 1:01 PM
But the "sproing" tells you when you're empty ;)

So does squeezing the trigger:)

missiontrails
09-30-2009, 1:02 PM
I was going to try a Wolf Extra power spring, but I'm thinking that may cause short stroking with .223. Don't want to push my luck.

reidnez
09-30-2009, 1:18 PM
So does squeezing the trigger:)

Touche, touche...

tomd1584
09-30-2009, 1:42 PM
glad to see it worked......

gemini1
09-30-2009, 4:42 PM
So how soft is soft recoil? 22LR, 22 WMR?

tomd1584
09-30-2009, 4:49 PM
So how soft is soft recoil? 22LR, 22 WMR?

probably like almost all other .223/5.56 AR's.........:p

missiontrails
09-30-2009, 5:08 PM
So how soft is soft recoil? 22LR, 22 WMR?

For me, it approaches the feel of a mid-length, but not quite all the way.

supermario
09-30-2009, 6:34 PM
So, If you bought a CMMG 9mm upper (has a ramped bolt, so you can use 5.56 hammer), all you would need to add, is the magblock and magazine.
Thats really good info. With your lower, you can just pop on a cmmg upper, get ur 9mm magblock, drop in, insert mag and fire.. Thats pretty cool..

Missiontrails, what kind of 9mm buffer is it? Make? Thanks

missiontrails
09-30-2009, 6:57 PM
So, If you bought a CMMG 9mm upper (has a ramped bolt, so you can use 5.56 hammer), all you would need to add, is the magblock and magazine.
Thats really good info. With your lower, you can just pop on a cmmg upper, get ur 9mm magblock, drop in, insert mag and fire.. Thats pretty cool..

Missiontrails, what kind of 9mm buffer is it? Make? Thanks

It's a Colt, PK Firearms has them for $25. I bought the Colt 9mm buffer because it's 5.2oz, vs. the RRA which I believe is 5.6oz.

tony soprano
10-05-2009, 12:59 PM
It's a Colt, PK Firearms has them for $25. I bought the Colt 9mm buffer because it's 5.2oz, vs. the RRA which I believe is 5.6oz.Missiontrails, pardon the threadjack but I have a derivative question related to your buffer choice. I wanted a featureless build so I've cobbled together a 16" carbine upper with a fixed A2 stock/buffer/spring/buffer tube. I just learned that the standard rifle buffer weight is 5.2 oz. Given your success with the 5.2 oz 9mm buffer, I should be OK with the standard rifle buffer with a 16" carbine upper?

NSR500
10-05-2009, 1:03 PM
Given your success with the 5.2 oz 9mm buffer, I should be OK with the standard rifle buffer with a 16" carbine upper?

Are you using a Rifle buffer tube too? You're going to have to in order to use that rifle buffer. You cannot put a rifle buffer in a carbine tube without jeopardizing function.

tony soprano
10-05-2009, 1:12 PM
Are you using a Rifle buffer tube too? You're going to have to in order to use that rifle buffer. You cannot put a rifle buffer in a carbine tube without jeopardizing function.Yes, rifle buffer tube/spring/buffer.

NSR500
10-05-2009, 1:15 PM
In that case, yeah, you could use the rifle combo with a carbin upper. I've seen it done and in working condition before at the range. It does look a bit funny though. The 16" barrel with carbine system looks short compared to the rear of the AR with its full stock.

tony soprano
10-05-2009, 1:34 PM
In that case, yeah, you could use the rifle combo with a carbin upper. I've seen it done and in working condition before at the range. It does look a bit funny though. The 16" barrel with carbine system looks short compared to the rear of the AR with its full stock.Yeah, it's not the prettiest thing to look at; carbine upper, fixed A2 stock, and MMG grip. Part of the sacrifice required to keep the detachable mags in the PRK. Thanks for the response!

<on edit>I just had another thought. I'm *guessing* the standard rifle spring may be stouter than the carbine spring? No problems with the rifle buffer and spring?

NSR500
10-05-2009, 1:58 PM
I don't know about the spring rate, but the rifle spring is longer than the carbine.
I'm using Tubb springs in my ARs uncut, but all my guns are carbine except for one using a Magpul PRS. Seems to make no difference between the ones using the rifle and carbine buffers. YMMV though because I'm not using an off the rack spring. The Tubb setup is a CS Flatwire spring which they made universal to the carbine and rifle. Your supposed to trim the spring coil by coil to where the rifle functions reliably.

ar15barrels
10-05-2009, 2:20 PM
I bought a 5.2oz Colt 9mm buffer for my newest CMMG 14.5" M4. This is the first time I have fired this rifle. Today I ran 100 rounds of Federal XM193, 20 rounds of PMC Bronze .223, and 20 rounds of Sellier & Bellot .223. I warmed up the rifle with the Federal first, then I ran the .223 stuff in 5 round sessions, just to see if the bolt would lock back after the last round was fired each time.

NO FTF
NO FTE
All rounds went bang.
Bolt locked back after last shot with ALL ammo.

The rifle felt soft as far as recoil is concerned. No "sproing" sound from the buffer spring either. Great day.

Now can you see why I say the carbine gas system is over-gassed?

ar15barrels
10-05-2009, 2:23 PM
Missiontrails, pardon the threadjack but I have a derivative question related to your buffer choice. I wanted a featureless build so I've cobbled together a 16" carbine upper with a fixed A2 stock/buffer/spring/buffer tube. I just learned that the standard rifle buffer weight is 5.2 oz. Given your success with the 5.2 oz 9mm buffer, I should be OK with the standard rifle buffer with a 16" carbine upper?

Rifle buffers use a lighter spring to offset for the heavier mass of the buffer.
Carbine buffers use a heavier spring to offset for the lighter mass of the buffer.
The mere fact that carbines still run with rifle weight buffers and heavy tension buffer springs just goes to show you how over-gassed the carbines are...

missiontrails
10-05-2009, 3:08 PM
Now can you see why I say the carbine gas system is over-gassed?

Hell yes.

Dirtbiker
10-05-2009, 3:45 PM
Related but in reverse.

Can I run a rifle buffer in a 9mm rifle (with an A2 stock) ? I am currently running a 9mm buffer with a nylon spacer.

tony soprano
10-05-2009, 4:09 PM
Related but in reverse.

Can I run a rifle buffer in a 9mm rifle (with an A2 stock) ? I am currently running a 9mm buffer with a nylon spacer.Dirtbiker, based on the info I found in a number of searches, the standard rifle buffer weighs 5.2 oz. That's the same weight as the 5.2 oz Colt 9mm buffer that missiontrails started this thread about. As long as you're using the rifle buffer tube and stock, you should be good to go.

Nessal
10-05-2009, 4:14 PM
So does squeezing the trigger:)

But that requires you to rerack not to mention the risk of having a full magazine not sit correctly because the bolt carrier is in battery.

missiontrails
10-05-2009, 5:01 PM
But that requires you to rerack not to mention the risk of having a full magazine not sit correctly because the bolt carrier is in battery.

Or you could just toss aside the AR and fire a Garand. Then, you will FOR SURE know when you are empty.

God Bless The Mauser
10-05-2009, 5:36 PM
Or you could just toss aside the AR and fire a Garand. Then, you will FOR SURE know when you are empty.

And so will everyone else ;)