A2 Flash Hiders and Accuracy

[trackmagic]

I am in the middle of building a new upper. My goal is to make an AR that will drive tacks. I have a match grade barrel, a FF hand guard is on order and I will put a 4-14X scope on it.

I feel pretty good with everything I am putting on the gun except the A2 flash hider that I bought for $15.

The flash-hider affecting the bullet does not make me worried (it should be gone before the gas gets to the flash hider), but I am worried about the compensation aspect of the A2 and barrel whip. I am wondering if the barrel whip will affect the follow-up shots.

Here is a slow-motion video of a gun with a compensator:
http://www.youtube.com/watch?v=PEBMlfhlxYg
(Just watch the end to see the barrel whip)

Here is one without:
http://www.liveleak.com/view?i=0c8_1361755333

The barrel without is being disturbed less for the one without the compensator

In theory, the barrel should return after the shot, but what do you think? Should I ditch the compensator or is this nothing to worry about?

[Travis B]

Do you have the ability to max out the barrel and ammo accuracy? If not, the flash hider shouldn't be your biggest concern.

[trackmagic]

Do you have the ability to max out the barrel and ammo accuracy? If not, the flash hider shouldn't be your biggest concern.

Dude, this is a tech forum and I asked a technical question.

[saddlerocker]

Totally different barrels in your videos.
A stainless bull barrel and a standard M4 profile barrel.

So I wouldnt base any kind of assumption from those references.

You would need to see 3 barrels of the same material and profiles. One with a Brake, one with a flash hider, and one with no muzzle device.

Barrel whip will have much more to do with the barrel material and profile than any muzzle device.

A short bull barrel will have much less whip then a lighter profile and/or longer barrel.

I guess I dont really know what your asking.
A brake/comp will reduce muzzle rise/recoil allowing the fastest follow up shots. Any Barrel whip will be over way before you can get another shot off.

[MistWolf]

I am in the middle of building a new upper. My goal is to make an AR that will drive tacks. I have a match grade barrel, a FF hand guard is on order and I will put a 4-14X scope on it.

I feel pretty good with everything I am putting on the gun except the A2 flash hider that I bought for $15.

The flash-hider affecting the bullet does not make me worried (it should be gone before the gas gets to the flash hider), but I am worried about the compensation aspect of the A2 and barrel whip. I am wondering if the barrel whip will affect the follow-up shots.

Here is a slow-motion video of a gun with a compensator:
http://www.youtube.com/watch?v=PEBMlfhlxYg
(Just watch the end to see the barrel whip)

Here is one without:
http://www.liveleak.com/view?i=0c8_1361755333

The barrel without is being disturbed less for the one without the compensator

In theory, the barrel should return after the shot, but what do you think? Should I ditch the compensator or is this nothing to worry about?

A thicker diameter barrel will have less flex (barrel whip) than a thinner one.

The bullet exits the muzzle around 3000 fps, give or take. Oncethe muzzle is uncorked, the gases are traveling at about 5700 fps and will pass the bullet. That's why an even and clean crown is important to accuracy

[Iraqgunz]

The point he is making is that most shooters cannot even shoot to the potential of their weapon. The possibly sole exception are those that shoot from rests and never stray from it.


Dude, this is a tech forum and I asked a technical question.

[bp7178]

Barrel whip isn't so much the issue as the accuracy in which the muzzle device is machined when it comes to the A2. Mounting with a crush washer or shims can also effect how concentric the device is when installed.

There are a great many rifles with comps mounted which can shoot very accurately. Probably even a great number which can shoot accurately with an A2.

Shoot the rifle with it installed and without. Very easy way for you to find out. The most it will cost you is a washer.

[markm]

Dude, this is a tech forum and I asked a technical question.

He makes a legitmate point. If you're planning to shoot black hills garbage or something, don't even worry about it.

That said... if you are confident your ammo will be very good, skip the A2 and go with a heavy profile barrel with either no muzzle threading, or an A1 flash hider that has symetrical cuts.

[Failure2Stop]

Muzzle devices degrade mechanical precision.
It might be to a degree that is transparent due to ammunition inconsistencies or the plethora of external influences/variables, but if you want absolute precision a bare, non-threaded, properly crowned muzzle is the way to go.

[sinister]

Install hand-tight using Locktite and you'll never notice it. There is negligible difference.

Tighten that thing on there and you'll notice a distinct difference.

[trackmagic]

My barrel is not a bull barrel. It is actually a Rainier Select 16". They say it is supposed to shoot sub-MOA with match ammo.

I do actually plan to mostly use this for rested shooting. I have been shooting my bolt action 223 for a while like that, but I wanted something that would compete with it in an AR platform.

The accuracy loss may be in the noise of everything else, but for a relatively inexpensive part I figured it was worth asking. If for example I went from 1moa to 1.25moa because of my muzzle device I would probably skip on the A2. Since I try to push myself to shoot 1" groups when I use my bolt action. If it went from 1 to 1.1moa then I probably would not worry about it.

[Travis B]

Try it out. Shoot a few groups sans a2 and then shoot a few groups with it attached. Come back and post the results.


My barrel is not a bull barrel. It is actually a Rainier Select 16". They say it is supposed to shoot sub-MOA with match ammo.

I do actually plan to mostly use this for rested shooting. I have been shooting my bolt action 223 for a while like that, but I wanted something that would compete with it in an AR platform.

The accuracy loss may be in the noise of everything else, but for a relatively inexpensive part I figured it was worth asking. If for example I went from 1moa to 1.25moa because of my muzzle device I would probably skip on the A2. Since I try to push myself to shoot 1" groups when I use my bolt action. If it went from 1 to 1.1moa then I probably would not worry about it.

[BlackViper]

Trackmagic: I went through the same thing when looking at muzzle devices for my last build, which is essentially a 16” Noveske clone. I tested accuracy impact with just a thread protector, an A2 and a Smith Vortex. The A2 was a DPMS product so it may just be incorrectly machined, but groups at 100 yards opened up from about 1” to 1.5” for several 5 shot strings with various types of ammo. The Vortex, which is touted to improve accuracy caused a group size increase of slightly less than ¼ “.
I have since gotten another A2 which should be a quality product, but haven’t had a chance to test it.
The best way to find out about the impact is to just try it.
BV

[bruin]

A symmetrical flash hider (i.e. AAC Blackout FH), torqued to the minimum range of spec, would have a negligible impact on accuracy. But go with what F2S said if you want hands-down, zero impact from the end of your barrel.

[markm]

If you already have the barrel and it's not threaded, DON'T thread it.

[El Pistolero]

FWIW, I recall reading somewhere that Colt was over-torquing the flash hiders on M16s a while back and accuracy improved when they were loosened and properly torqued. I don't recall where I read it but I'm sure a Google search could dig it up. So yes, for a precision rig I would go with a naked and crowned muzzle.

[trackmagic]

It came with a threaded muzzle...Here is my barrel:

http://www.rainierarms.com/?page=shop/detail&product_id=3279

I don't mind testing, but I'll need to buy something else to test to see if I actually get a change. It sounds like it can degrade accuracy so I plan to do those tests. I'll probably go with a symmetric FH and compare it to the A2. I'll post back here when I have results.

I am waiting on a Vltor FF hand guard (which is also what my scope mounts to). Its back ordered so it might not be soon that I can give test results unfortunately.

[fdxpilot]

I am waiting on a Vltor FF hand guard (which is also what my scope mounts to). Its back ordered so it might not be soon that I can give test results unfortunately.

You want a tack driver, yet are going to mount your scope to a free-float handguard? :rolleyes: The reasoning behind a free-float is the things that move the handguard around will not affect the barrel, so the handguard is not the place to mount your scope. Get a cantilever mount for the receiver rail, if you need to move your scope forward.

[308sako]

No one has yet mentioned the harmonic portion of a barrels "accuracy/precision" change the length or weight of the barrel and you have effectively changed the barrel.

Gas exits before the bullet does, it's called blowby. Additionally, immediately upon the bullet clearing the crown the gases which were driving the bullet bypass the bullet because their velocity far exceeds the bullets, albeit briefly.

The reason to avoid a threaded muzzle on a precision rifle barrel is as you suspect the potential lack of concentrically attaching any device, whatever type you chose. More importantly however is the FACT that removing metal from the outside of the barrel infinitesimally increases the bore diameter at that point. This is a known cause of inaccuracy, avoid it when possible.

It is wise to try to make best use of all the options we are offered in the market place to build/assemble the rifle of our dreams. But I must advise that trigger time will do more than shopping time. Don't sweat the small stuff until YOU can shoot the difference you think might be found.

[usmc1371]

Go to the range with the A2 installed and shoot some ten shot groups. Take the A2 off and shoot more ten shot groups. If and I think it's a big if, it actually shoots noticeably better with out the A2 try a thread protector and be on your way. My 16" BCM ss holds less than 1moa out to 700 yards with an A2 so I don't try to fix what ain't broke.

[trackmagic]

You want a tack driver, yet are going to mount your scope to a free-float handguard? :rolleyes: The reasoning behind a free-float is the things that move the handguard around will not affect the barrel, so the handguard is not the place to mount your scope. Get a cantilever mount for the receiver rail, if you need to move your scope forward.

The Vltor CASV is designed for what I am doing...

http://www.vltor.com/casv-m.htm

It has a rail that is attached to the upper receiver and then to the hand guard. It is similar to a monolithic reciever.

[trackmagic]

Go to the range with the A2 installed and shoot some ten shot groups. Take the A2 off and shoot more ten shot groups. If and I think it's a big if, it actually shoots noticeably better with out the A2 try a thread protector and be on your way. My 16" BCM ss holds less than 1moa out to 700 yards with an A2 so I don't try to fix what ain't broke.

There is no harm in shooting with nothing threaded onto the end is there? I'm pretty sure the answer is no, but figured I better ask.

[AKDoug]

There is nothing wrong shooting with bare threads. I put a thread protector on my daughter's 6.8 SPC and tightening it finger tight with blue loctite. It didn't change the accuracy one bit.

[HelloLarry]

The threading itself can alter the barrel. Button rifled bores can open up when the outside is turned; hammer forged bores can get tighter when turned. Cut bores are pretty stable.

Also as mentioned, tightness of the flashhider can affect accuracy.

In short, they can be problematic when ultimate accuracy is desired.

But keep in mind that the Army teams all shoot with flashhiders installed. And they kick everyone's butt. :)

[ClearedHot]

A flash hider such as the Smith Vortex (which only needs to be hand tightened) would probably have the least adverse affects on accuracy.

[usmc1371]

Yes you can shoot with bare threads. The thread protector is just there to keep the threads from being dinged up.