AR installing flash hider. Fancy tools needed?

T

Teac

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So I have to install a new FH and all online info uses special brackets to hold the receiver in a vise and special wrench.

Is all this needed to not damage the gun?

If I just hold the rifle by the receiver and wrench the FH on, will I twist or damage something ? It should "feel" the same for the rifle as in both cases the torque goes from the barrel in the action, trying to twist it.

Just dont want to damage the AR :)


cheers
Matt
 
NEVER hold the rifle by the receiver to change flash suppressors! Always clamp the barrel.

If you have a stuck flash suppressor you could tweak the barrel and damaged the receiver.

Put two blocks of wood in a vise, clamp the barrel between them. I've even used a strap wrench around the barrel when I knew it wasn't going to be a heavy pull.
 
Armedsask said:
NEVER hold the rifle by the receiver to change flash suppressors! Always clamp the barrel.

If you have a stuck flash suppressor you could tweak the barrel and damaged the receiver.

Put two blocks of wood in a vise, clamp the barrel between them. I've even used a strap wrench around the barrel when I knew it wasn't going to be a heavy pull.
Click to expand...

thats what I thought as well, but even in this Brownells video they hold it by the receiver

http://www.brownells.com/.aspx/lid=11441/learn/
 
In the CF we torque the compensators from 46 to 51ft/lbs.

I also clamp the barrel in a vice when doing this to make sure that no torque is applied to the receiver itself, removing the risk of damaging it.
 
Do what Armedsask recommends (except if he's giving you advice about women or money, or both). :D

When using a crush washer make sure you get at least 90deg of "crush" when you tighten the device down. By that I mean tighten the muzzle device "hand tight" then use your wrench to index it properly but tighten it down at least 90deg. You may need to tighten it down greater than 90deg to get the device to index properly.
 
What about on shorter barrels like 11.5? Is it safe to vice the barrel?? (Obviously have to remove the handguard) or would the strap wrench and flash hider wrench be the better choice?
 
If you are doing a short barrel and floated rail/tube that needs to be on prior to the muzzle device, clamp the upper in receiver blocks and use a jamb nut.
It's very important to eliminate torque stress on the upper from wrenching on the barrel.
 
-[Crosshair]- said:
In the CF we torque the compensators from 46 to 51ft/lbs.

I also clamp the barrel in a vice when doing this to make sure that no torque is applied to the receiver itself, removing the risk of damaging it.
Click to expand...

I found that flash hider being cranked on tight didn't do any favours to the accuracy of my National Match gun...

I took off an A2 flash hider from an Armalite barrel that was torqued on HARD and replaced it "finger tight" with permanent loc-tite. Well.... maybe a bit tighter than finger tight. Certainly nothing that would damage the action in the proper block in a vice rather than clamping the barrel.

Getting the OLD one off if it is torqued on tight might be another story - and I would recommend clamping barrel.

Anyway - back to my point... I thought the barrel was a bad one, and it barely held 2 MOA testing with a scope on an A4 receiver. But it was a low round count barrel, and I'm cheap -- so I took a leap of faith and re-mounted it on an A2 instead of buying a new barrel when I dove into the National Match gun project.

I did a bunch of things different - so I don't know if the flash hider torque was the sole cause of that barrel's problems.... but it is on the receiver with less than 30 foot pounds now (it was on the old one with something atrocious, probably over 60) And I replaced the foresight with a clamp on. The clamp on is snug but not overwhelmingly tight, also loc-tited, and I prefer the even pressure it puts on the barrel compared to the old push-pins.. The gun is perfectly capable of shooting the US matches "clean" right now - although I am not.:redface:

I "suspect" that the tension of the old pins in the standard foresight/gasblock, combined with the torque on the flash hider were the reasons this barrel was garbage. Mounted properly with all these things "relieved" it shoots like a dream. I wouldn't have even bothered with the hider, except that it needs to get out of the way to swap out the gas block. I'm glad I did it.

Now - having said all that - probably the CF guns need their flash hiders a little snugger than "finger tight." But with the crush-washer used properly, still no tighter than a short hand wrench can do it. My guess would be in the 30 foot pound range for most applications would be enough to hold it on...

Tight is good - STRESS is bad. IMO.
 
A lot of flash suppressors and other muzzle devices are going to trap and build up carbon fouling at the barrel crown - this uneven build up of crap is going to affect bullet flight and could bugger with accuracy more than the torque of the device....
 
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