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Flat Broke
06-03-2008, 4:33 PM
So I'm getting close to nailing down the spec for my first AR upper, and the handguard selection process has me looking in a couple different directions.

The JP VTAC would probably be my first choice, and in the grand scheme of things, it isn't that expensive.

Next down the list would probably be YHM's VTAC clone, though it doesn't really save that much $$$ for what is probalby a slight reduction in quality.

After these two, I'm looking at something like a DD Omega, Samson, etc. which starts to drive the cost up significantly, and may not really be what I want.

This got me to thinking about using tools and time to make a JP knockoff from a FF tube. The tubes can be had much cheaper, and if you add in an hour at the mill to cut some ventilation/accessory slots, dropping the part with a buddy who does regular runs at Dunham Metal Finishing, and purchasing a top rail which is all I really want at this juncture, I'd be $$ ahead, have something unique, and cover all my bases.

The main part that I'm concerned with is how reliable standard FF tubes are in terms of staying put. If I mount a rail to the tube, I need to know it isn't going to rotate relative to the receiver. So what expereinces do people have with std free float tubes in non-bench gun scenarios? Any insight into different attachement architectures would be cool too.

Thanks in advance,
Chris

IGOTDIRT4U
06-03-2008, 5:54 PM
My Wilson Combat (full factory build) has had no problems.

C.G.
06-03-2008, 5:57 PM
Often FF tubes are glued on. It depends on the adhesive as to how pemanent or not an installation is, but in my case I had an FF tube come loose and that was without anything on it.

novanryder
06-03-2008, 6:27 PM
FF tubes can be attached a bunch of different ways, but the most common that I've been seeing among people's builds are the 2 most reliable...

1) Usually "standard" FF tubes (I assume you're talking about the ones that are pretty much just a bland tube screwed onto the upper receiver threading) hold the barrel on, hence the need to screw it onto the upper receiver. This is pretty much the most stable way to do it based on attachment; structural rigidity and strength depends more on the material from which the rail is made. If you're going to make your own tube that requires this method of attachment, make sure that you get the threading right on the interior of the tube and have whatever metal you're going to use be something that won't rust or you're asking for trouble. It also helps to look up some facts about metalurgy because it's possible for two different metals to to undergo a chemical process called "redox" when they come in contact with each other, essentially destroying one or both of the metals. Needless to say, that's a bad idea on a gun. The thing to remember is that FF tubes help with function, but they're more directed towards fashion that anything else. For example, Alexander Arms sells rifles with just a solid, straight black tube on their guns. Practical, gets the job done... but not very pretty looking. However, it DOES keep out dirt and other things in trade for increased heat. Therefore, the main problem with solid tubes is heat, and with vented tubes, dirt.

2) Other popular tubes clamp on over the barrel nut and use the exterior nubs of the barrel nut to get the orientation of the tube correct and/or prevent the tube from rotating. If you're not big on tool work or worrying about torquing parts down to spec, then the clamp on rails are a wonderful way to install a rail without having to remove much apart from the stock handguards (in a lot of cases). From what I have seen, clamp on rails tend to be cheaper than screw on rails. Midwest Industries and other companies make some rather nice clamp on FF tubes that aren't too expensive. I own one of the MI rails like this and I can say from personal experience that it's an extremely good rail, stylish, functional and pretty solid. Clamp on rails typically are not as solid as rails that you have to screw onto the upper receiver, but since the idea is to get pressure off of the barrel that doesn't necessarily matter much, depending on your apllication. If you have a lot of pretty heavy accessories I would go with a screw on rail.

If you can machine your own then right on dude! That's awesome. While you're doing that think up some way to prevent tube rotation due to vibration/shock. Most companies did this by drilling holes in the side to allow screws to secure the tube against the barrel nut. Also keep in mind that if weight is an issue, milling out the rail is a good idea but don't go too nuts or you'll compromise the solidarity of the rail. On another note, you said you needed a top rail only, I believe. If that's the case, take a look at the Daniel Defense Omega rails. They have a slightly protruding top rail which lines up with the rail on the upper receiver to provide continuous mounting surface. Since money seems to be an issue for you, I won't go too far into describing the Vltor monolothic upper receivers, but it's a thought to consider since they more or less eliminate the need for mounting a rail. As far as failure rates go, I don't think there's a huge difference between regular old tubes and nice FF rails, but don't quote me on that. What's important is secure mounting, anti-rotation features, heat venting, gas block coverage (or exposure) and possibly closing up the end of the tube so stuff doesn't get in there. I bought my 10" clamp on MI rail from Bravo Company, if you want to check it out. I don't have any pictures currently because I had to disassemble my gun for some work but if you want to see it let me know and I can take some pictures of it unmounted.

shark92651
06-03-2008, 6:51 PM
To answer your question, none of the forearms you mention above is going to be moving on you if properly installed.

Cypriss32
06-03-2008, 7:41 PM
I just ordered a JP handguard, and MIAD grip. It was 210.00 shipped, NOT expensive at ALL!

novanryder
06-03-2008, 10:51 PM
those more or less sum it up, but hey... never hurts to be informed :P

ar15barrels
06-03-2008, 11:43 PM
Even though you may be able to make a $50 freefloat tube LOOK like a JP, you would not have any of the advantages of JP's barrel nut system.

Flat Broke
06-04-2008, 12:11 AM
I really appreciate the time taken for the intricate post. While I wouldn't call myself a metalurgist, I've done enough little projects for boats, cars, and bikes to have worked with quite a few different metals, so I hear you loud and clear on the dissimilar metal issue. I don't have a lathe, just a lowly Bridgeport without DRO's, so turning interior threads on a tube would be tricky as I'd have to seutp a cutter and use the power feed on the head to do the threading. I'd probably waste enough $$ in botching one getting the feed rate right for the thread pitch of a barrel nut, that between the finished homebrew version and wasted material, I could have bought the YHM, or even the JP.

What I was actually thinking about doing was buying a pre-mfg'd float tube (so long as it had a reliable attachment method), milling out some cooling slots, drilling and tapping for a top rail, and maybe some 3" rails at the front located at 3 and 9 o'clock, then a bipod stud at 6'oclock. I've seen some tubes run in the $50-60 range, and rails as inexpensive as $25 for enough length to cover the tube, but I don't know if the tubes would be of a suitable mounting method. I guess, that ideally, I'd need one that WAS the barrel nut(I think the YHMs might be this way). That way, it just threads down onto the upper, and I could use an optic mount (or a small clamp if whatever optic I settle one would be mounted further aft) to bridge the rail on the receiver and on the tube to hold things in line. The main downside to this setup that I can see would be that I'd have to assemble the rifle with the new tube, torque the tube to spec indexed so the gas tube will fit through properly, then mark the tube for the top rail. Then disassemble, mill the tube, drill and tap for the rail, then reassemble and hope that it indexed back to the same spot when torqued to spec. While I'm typing this, I'm sitting here wondering how I measure the torque of the tube that is now the barrel unt when I'd be using a strap wrench :confused: Seems like a lot of work to reinvent the wheel and save $60-80 bucks... but I'd love some input from Randall or other smiths just the same :)

Chris

ar15barrels
06-04-2008, 12:18 AM
I could use an optic mount to bridge the rail on the receiver and on the tube to hold things in line.

Don't bridge the receiver and handguard with an optic, period.
The handguard always moves around at the barrel nut threads.
That top rail is fine for an iron sight or a laser designator, but not an optic.

Flat Broke
06-04-2008, 12:25 AM
Even though you may be able to make a $50 freefloat tube LOOK like a JP, you would not have any of the advantages of JP's barrel nut system.

I don't disagree at all, but I started thinking about their barrel nut system, and I'm a little confused. As I understand it, the outer nut which the tube bolts to threads onto the receiver, but it can't really torque down against anything except the end of the threading right? (which you really wouldn't do) Then the barrel nut threads into the outer nut, effecitively relying on the torque from the barrel seating into the receiver to tension the threads between the outer nut and the barrel nut. So the setup effectively works like two nuts run down on a bolt. The loading on one set of threads helps to keep the other set of threads tensioned. So essentially, the system is still only held in place by 35ftlbs of torque with the gas tube acting as a cotter pin in a castle nut. In that sense, is it that much different than a tube that is in itself the barrel nut? I'm not knocking the JP in any way. I'll probably end up going that route, but I like exploring alternatives that utilize tools and skills I already have. If I have a skewed version of how the JP works, please set me straight as I'm not trying to start an argument etc, just trying to learn about something a little more complicated than my box of AK variant parts :)

BTW, if you sell the JP I'd be interested in coming by sometime in the next few weeks and checking one out.

Thanks for your input,
Chris

Flat Broke
06-04-2008, 12:26 AM
Don't bridge the receiver and handguard with an optic, period.
The handguard always moves around at the barrel nut threads.
That top rail is fine for an iron sight or a laser designator, but not an optic.

Thanks for the heads up. So even on the higher end stuff like the DD, LaRue, etc, this is true? I just want to know so I don't make any bonehead moves.

Thanks,
Chris

novanryder
06-04-2008, 12:29 AM
Yeah, the biggest trouble with taking these matters into your own hands is the tools. Randall here has everything you'd probably need if you want to ask him to do something custom like that, but of course it's $$. I'm actually all for spending more money and botching a tube to get the learning experience of making my own parts, but to each his own.

I actually have a YHM Lite rail in Spectre length. It wasn't pricey and it's a phenomenal rail... YHM really does a good job. This particular rail has huge holes milled out of it for venting (which is why I chose it) and it's super light. On top of that, you can buy end caps made by YHM that just screw right into the end of the rail, which I'm going to do for my .50 Beowulf. The only downside about it is that you have a break in the upper rail because of the YHM ring that separates the rail from the upper receiver, but is used to hold the rail in place. I would actually recommend a YHM Lite rail because it's just so pretty. :P

Your idea about milling out a pre-manufactured tube is right on the money. Keeps it simple, and you can mod it as you need. There's something you might want to consider about this, though, that might be helpful. Let's say you find a tube that screws on, but it screws on to a piece that's totally separate from the tube and is basically the barrel nut. Mill some notches out of the barrel nut and thread some holes through the sides of the tube to screw it onto the nut. Viola, anti-rotational screws plus secure attachment and custom milling/rails to your specs. Just a thought.

I would suggest that you NOT use some kind of mount to keep the top rails straight. That just sounds like something bad waiting to happen in my opinion. You're dead on about the indexing, torquing etc... basically all gunsmiths do is take a torque wrench, put it to an armorer's wrench, and you get the idea. Indexing tend to be guess and test.

SO! Bottom line: if you want experience making your own parts, here's a good adventure for you. Hell, maybe you'll come up with something cool that you could even patent and/or sell. But you'll be spending WAY more time and effort to get it made rather than spending a few more bucks to get something that's already had this done. :P

ar15barrels
06-04-2008, 12:31 AM
I don't disagree at all, but I started thinking about their barrel nut system, and I'm a little confused. As I understand it, the outer nut which the tube bolts to threads onto the receiver, but it can't really torque down against anything except the end of the threading right?

The part you are missing is that the outer sleeve gets loctited to the receiver and cured under tension.
Then the barrel gets installed and the inner sleeve torqued into place.

ar15barrels
06-04-2008, 12:31 AM
So even on the higher end stuff like the DD, LaRue, etc, this is true?

Yes.

ar15barrels
06-04-2008, 12:35 AM
basically all gunsmiths do is take a torque wrench, put it to an armorer's wrench, and you get the idea.
Indexing tend to be guess and test.

For most people, that would be true.
I have some neat ways of fixturing and indexing that are much more precise.
That's why my rail installations come out better than average.
Uppers last longer when barrels nuts are precisely located to center gas tubes in the gas key.
Gas tubes are stress relieved during installation.

Flat Broke
06-04-2008, 12:50 AM
...
Your idea about milling out a pre-manufactured tube is right on the money. Keeps it simple, and you can mod it as you need. There's something you might want to consider about this, though, that might be helpful. Let's say you find a tube that screws on, but it screws on to a piece that's totally separate from the tube and is basically the barrel nut. Mill some notches out of the barrel nut and thread some holes through the sides of the tube to screw it onto the nut. Viola, anti-rotational screws plus secure attachment and custom milling/rails to your specs. Just a thought...

SO! Bottom line: if you want experience making your own parts, here's a good adventure for you. Hell, maybe you'll come up with something cool that you could even patent and/or sell. But you'll be spending WAY more time and effort to get it made rather than spending a few more bucks to get something that's already had this done. :P

I can buy a nut like what you're talking about... I'd be the YHM nut that 's included in their rail system :) By the time I buy that a rail or two and some tube, I can buy their JP clone modular setup.

I wanted to say thanks to everyone in this thread for imparting some knowledge on a newb. I think I'll wait until I get my upper in hand before I worry about this too much more. From tonight's exchange and associated research, I now have a very good understanding of how the various free float systems interface with the receiver. That will be important for deciding what I do once I have my upper.

Thanks,
Chris

randy
06-04-2008, 6:13 AM
We are lucky to have Randall on Calguns to ask and answer questions. Listen to what he says it will save you money and let your rifle live up to it's potential.

Now if he could just learn to shoot them;)

Flat Broke
07-16-2008, 7:28 PM
Back from the dead... :) I've had my upper for a couple weeks now, and pick up my lowers on Saturday. Since I've had the upper in hand, I've been kicking around the free float question again. I'm pretty much settled on either a JP or a DIY'd DPMS 2 piece setup.

If I went the DIY route, it'd be uber easy to do what I want to do with regard to ventilation for the DPMS tube. Where I wanted a little more clarification/input was with regard to how I was thinking about securing the assembly and providing anti-rotation/inedexing possibilities. I can't find a picture of the DPMS barrel nut that is used on their free float tubes, so I'm guessing that it either looks similar to the YHM model, or is just a threaded cylinder (more likely) with the gas port holes drilled every 18* or so. What I was thinking about doing was drilling anti-rotation screw holes every 45 or 60 degrees (6 or 8 holes), and 2 holes on the actual tube. Then I would install the barrel/barrel nut with a dab or two of red loctite. Then thread the tube on, and torque down the nut while paying atention to my indexing to get my 2 holes in the tube to line up with the holes in the nut.

The main question here is; is the red loctite on the barrel nut a bad idea? We're not talking globs, just a couple drops. And obviously whether or not the concept seems feasible.

I still may just buy the JP and call it done, but something about a little DIY appeals to me.

Thanks,
Chris

BTW, I'll post the obligatory "finished my build thread" once I nail this piece down ;)

ar15barrels
07-16-2008, 10:01 PM
Back from the dead... :) I've had my upper for a couple weeks now, and pick up my lowers on Saturday. Since I've had the upper in hand, I've been kicking around the free float question again. I'm pretty much settled on either a JP or a DIY'd DPMS 2 piece setup.

You are over thinking this way too much.
The DPMS barrel nut is just a cylinder with the large hole for the barrel and a bunch of small holes for the gas tube.
The nut is a full 2" in diameter, just like the handguard tube.
The front 3/8" or so is reduced in diameter and threaded.
The tube simply threads on and stops.
There is no ability to index the tube because it's round.
There are no holes that need to be aligned anywhere.

The nut simply gets tightened on to the barrel/receiver and the gas tube slides through the nut.
Then the handguard threads on to the barrel nut.
What I do if I am adding a bipod/sling stud is I put a setscrew through the handguard tube at 6:00, well into the barrel nut.
I loctite the setscrew.
If you ever need to remove the tube, just take out the setscrew and unscrew the tube.
I often will put some loctite on the threads where the handguard tightens on to the nut if I am not setscrewing the tube to the nut.

Flat Broke
07-16-2008, 10:34 PM
KISS eh? ;) I can live with that. Just a couple more seemingly stupid questions and I'm good to go. Once properly torqued, should I ever have to worry about the barrel nut loosening during the course of normal use (even in the most unreasonable heat cycle (hot day/cold night in the Gobi desert :) ) scenarios etc? I don't ever see using a forward grip, so there really wont be tons of leverage on it, but I'd still like to know how stable it will be. Locktite the barrel nut, or just lube, torque/loosen 3x then retorque and call it done?

Randall,
Thanks for all of your input on this thread. I really appreciate you not just saying, "buy the JP and be done with it". It takes a lot more time to address my questions, and I really appreciate that. I see you list the DPMS 2pc non vented std. tubes on your site. Do you have any on hand? I'll be in Torrance on Friday and could easily meet up with you in the afternoon.

Thanks again,
Chris

ar15barrels
07-16-2008, 10:46 PM
Locktite the barrel nut, or just lube, torque/loosen 3x then retorque and call it done?

I see you list the DPMS 2pc non vented std. tubes on your site. Do you have any on hand?

Lube and torque 3X for the barrel nut.
It won't move if it's put on tight.
Loctite the tube to the nut.
Setscrew the tube to the nut if you add a VFG, bipod or sling that requires anti-rotation features.

I have DPMS rifle and carbine length freefloat tubes in stock.

mltrading
07-16-2008, 10:51 PM
KISS eh? ;) I can live with that. Just a couple more seemingly stupid questions and I'm good to go. Once properly torqued, should I ever have to worry about the barrel nut loosening during the course of normal use (even in the most unreasonable heat cycle (hot day/cold night in the Gobi desert :) ) scenarios etc? I don't ever see using a forward grip, so there really wont be tons of leverage on it, but I'd still like to know how stable it will be. Locktite the barrel nut, or just lube, torque/loosen 3x then retorque and call it done?

If you are using torque wrench set up, you don't need to do the (tighten-loose) X3 trick. Just torque to correct number. Usually something around 80 ft-lb will guarantee no loose under normal circumstances.

Unless you are using JP/Vtac forearms, do not use Loctite. Only JP suggested to use red Loctite on outter nut. Other manufacturers do not suggest Loctite.

By the way, doing slots and other modifications on an ordinary forearm is fun without doubts. However, being a vendor, I suggest spending a little bit more money and getting an already-well-built product.

Flat Broke
07-17-2008, 12:00 AM
Randall,

PM me some info on when you are available for me to swing by. Thanks again for your input.

ML Trading,

I'll be using a torque wrench on a DPMS multi-tool for the nut, but seeing as how the threads on the nut will be fresh, I'd feel more comfy going through the torque sequence a couple of times to seat everything. The small increase in time required to help seat/burnish/stretch threads just seems like a good practice to me. Granted I don't know jack about ARs; and it may well be nit-pickey overkill, but I have the time, so I might as well. Just for kicks, I could set up a dial indicator and see if each successive torque cycle moves the rear of the nut closer to the receiver indicating that the threads were indeed seating in. It'd make for good conversation if nothing else.

As for buying the JP over butchering the DPMS, for one it's not "a little bit more". The JP is nearly 3x the cost of the DPMS tube. I budgeted for the JP so the cost isn't the primary factor; but would I get an extra $100 of utility for my needs out of the JP? No argument the JP's a better product; but truth be told, if I had a lathe I wouldn't buy either. For me, easily half the joy of owning stuff like this, is making it my own, either through configuration, or customization.

I apreciate the insight and agree with the sentiment, as I would probably tell someone else the same thing.

Chris

ar15barrels
07-17-2008, 12:11 AM
If you are using torque wrench set up, you don't need to do the (tighten-loose) X3 trick.

You should still do it.
It burnishes the threads.

ar15barrels
07-17-2008, 12:14 AM
I'll be using a torque wrench on a DPMS multi-tool for the nut

DPMS multi tool is great for standard barrel nuts, but don't use them on freefloat barrel nuts.
The pins are far too short.

PM sent.

CleverName
07-17-2008, 3:40 PM
I didn't want to start another thread, and apparently ARFCOM won't let me register.

So: what's the best free-float wrench? I'm looking at YHM, and eventually LaRue for handguards (on my eventual later build). Will the YHM wrench work for both?

ar15barrels
07-17-2008, 4:30 PM
I didn't want to start another thread, and apparently ARFCOM won't let me register.

So: what's the best free-float wrench? I'm looking at YHM, and eventually LaRue for handguards (on my eventual later build). Will the YHM wrench work for both?

There is no single "best" wrench.
You need different ones for different brands.
YHM should work with LaRue.

My go-to freefloat wrench is the DPMS freefloat tube wrench.
It uses screws as the pins so you can replace them if you break them.
It's only a two-pin setup though.
I like the YHM better in the respect that it has 3 pins, but the YHM is so short that you have to add a cheater bar to it.