Question about "timing" and carbine AR15s

[Ash]

Just saw this video on AIM's blog on their website.

http://www.youtube.com/watch?v=VR3fi1wCSmM&feature=player_embedded

So should I be concerned about this in the future.

Thanks.

-Dan

[5.56NATO]

The ar was designed to use a 20in tube. Where the gas port is on the 20in tube ensures that the gas pulse is such that the case has retracted from the chamber wall and is not sticking before the gas actuates the bolt/carrier. The car/m4 have much shorter gas tubes and a much greater gas impulse that fills that gas tube, and by design they have issues with the case still being held to the chamber wall by the time the overpowered gas charge hits the bolt/carrier. The m4, if it is an actual m4, gets around this issue somewhat by having a heavier buffer than a standard car. Heavier buffer means it takes more time for the moving parts to get going, allowing the case to contract before extraction is forced. All of this is why I much prefer a 20in tube over a shorty any day. If some one gave me an M4 or car (of wich I have run multiple thousands of rounds through) I would be happy but a 20in tube is the right thing as far as the ar goes.

[Ash]

Thanks for the reply. I guess the question for me is, is there anything to help compensate for that with my new bushy? Or is it just something to live with?

It's difficult for me to believe that the carbines are still doing as well on the market if they have a flaw like this. The only thing I can think of is that others are in the same boat as I am and "missed the memo" about it so to speak.

-Dan

[Flinter]

Does your Bushy fire Wolf ammo without jamming? If it does, I woulnd't fix what isn't broken.

Your option is to increase buffer weight until you get to the point where the rifle is short stroking....then back off one buffer weight.

I'm running an H buffer in a 16 inch tube without any problems. I do, however, have an M16 bolt which adds a little weight.

[circuits]

I avoid wolf because the cases stick in most of my rifles - Colts, Armalites, BCM, DPMS, Daewoo and FN among them, 20" and 16" and 14.5" and 10.5" and 7" barrel lengths. The phenomenon is real, not generally related to timing, nor to barrel length, nor even to the use of steel cases or lacquer.

I use Barnaul/Brown Bear/Silver Bear/Golden Bear because it runs without a problem in everything I own, and costs about the same as Wolf, sometimes less.

The best thing for Wolf is if you want to run it, try some in your rifle, and if it works, you're good to go. If not, don't buy any more.

[Schuetzenman]

Thanks for the reply. I guess the question for me is, is there anything to help compensate for that with my new bushy? Or is it just something to live with?

It's difficult for me to believe that the carbines are still doing as well on the market if they have a flaw like this. The only thing I can think of is that others are in the same boat as I am and "missed the memo" about it so to speak.

-Dan
There are different gas tubes available to deal with this problem. A heavier buffer is one way to approach the problem, using a pigtail gas tube or one with a gas block with a flow valve built into it is another. http://www.brownells.com/.aspx/pid=9947/Product/AR_15_M16_REGULATED_GAS_TUBE Link to a gas valve tube. http://www.brownells.com/.aspx/pid=1591/Product/AR_15_M16_PIGTAIL_GAS_TUBE link to a pig tail tube. Not overly well rated by the single reviews for both products. Then there are gas block / front sights with gas adjustmets in them. http://www.brownells.com/.aspx/pid=7592/Product/AR_15_M16_ADJUSTABLE_GAS_BLOCK Link to an adjustable gas block by JP Enterprises. I have one of these on a match gun, they do work but you will notice it is a picatinny rail type so you'd have to add a front sight to it. The bottom line to it all is Carbines have been trouble for many owners. I've seen more Carbines malfunction on ranges than full sized AR rifles, the gas pressure and timing is the reason why.

[Ash]

I use Barnaul/Brown Bear/Silver Bear/Golden Bear because it runs without a problem in everything I own, and costs about the same as Wolf, sometimes less.

Can you post the sites you use for ordering these? The best deal on Ammo that I found was from www.aimsurplus.com for the Wolf at $3.99 a box. I could have gotten it cheaper in bulk but figured that 500 rounds would be more than enough to fully test things.

As for the rest of the stuff, I'm at a total loss of where to begin. Thanks for the heads up guys. The first 40 or rounds I shot through caused some jams that I had originally associated with the fact that I was resting the rifle on a bench with the mag pressed into the bench. The mag's pretty sucky and has a lot of play in it, so much that by resting it on the bench the floorplate began kicking out. Up till reading this post I figured that was my problem. So when I ordered my ammo I got a couple extra clips to see if that yielded better results.

I'll keep you posted. Thank again for everything.

-Dan

[TEN-32]

As I recall you opted to buy your Bushy rather than build it? You should be good to go. Even if you had built the lower and bought the upper, should be a non-issue. Your mag problem is cheaply solved here:

http://www.44mag.com/category/223_ar15_magazines

[Sidartha]

How would a piston conversion affect this?
Not that I'm suggesting a $300 fix for a minor problem but I am considering building a piston rig and a new buffer tube weight obviously won't be helpful.

[TEN-32]

How would a piston conversion affect this?
Not that I'm suggesting a $300 fix for a minor problem but I am considering building a piston rig and a new buffer tube weight obviously won't be helpful.

A piston upper completely replaces the direct impingement gas system. Most piston uppers have a gas adjustment valve.

[5.56NATO]

How would a piston conversion affect this?
Not that I'm suggesting a $300 fix for a minor problem but I am considering building a piston rig and a new buffer tube weight obviously won't be helpful.

A piston in a shorty will run into the same issue if the piston/carrier/bolt reacts as fast as a standard gas tube rifle. It's not the fact that gas is used but the timing of the extraction, if extraction coincides with the case being stuck to the chamber you will always have this issue.

[Schuetzenman]

A piston in a shorty will run into the same issue if the piston/carrier/bolt reacts as fast as a standard gas tube rifle. It's not the fact that gas is used but the timing of the extraction, if extraction coincides with the case being stuck to the chamber you will always have this issue.

It and they don't react as fast. Trust me I have a 16" piston upper though it is a middy vs. typical carbine. The recoil impulse is very long, noticably so over what the weapon had when it was impingment. The gass has to start the mass of the piston moving, that isn't happening quick. Then the piston has to travel a certain distance before it contacts the gas key area of the bolt carrier. In this case it's a flat surface that the piston smacks into. That takes more time and then the bolt carier has to move back before the lugs are cammed to pen the breech, still more time. I would rate the feel of the impulse as about 3 or 4 times longer than when the weapon was impingment. Add to that that the upper, carrir and bolt stay very clean, no carbon and they stay very cool, no expansion from heating up.

Try putting two 30 round mags through any AR15 DI rifle then pull the bolt carrier out and feel the heat, careful you'll probably get heavy 2nd degree burns. Do the same thing with a piston converted rifle and the thing is barely skin temperature.

[sevlex]

This is an interesting thread.

My buddy has a 16" DPMS that regularly jams steel cases in the chamber. On the other hand, my 20" HBAR has no problems with steel case ammo. I have read the issue is with "tight chambers" made by DPMS. Now I'm thing that using a heavy buffer or even a pigtail gas tube (instead of reaming the chamber) would solve his problem.

[Doc Glockster]

I'm unable to watch the video because my computer doesn't have sound.

Could someone summarize what it's saying? :D

[Schuetzenman]

I'm unable to watch the video because my computer doesn't have sound.

Could someone summarize what it's saying? :D

The summary is about the Wolf ammo being cheap, reliable but not overly accurate ammo. They talk a bit about short carbine rifles having problems extracting steel cases because of the short gas tube. The mention that the steel cases aren't as elastic as the tempered brass case so it doesn't shrink back as much from the chamber walls making it harder to extract if the chambers start getting dirty.

[ready]

If you're not having problems, don't worry about it. I use an H2 buffer with an FA carrier in my 10.5. It won't cycle wolf unless I change out the buffer with a standard carbine weight buffer but cycles NATO stuff just fine. I don't have an H buffer around to see if that would be a happy medium but it might be. I've never had a stuck case, either. It'll just short stroke with underpowered ammo.

Bottom line, if it were going to be a problem, it would have been already.