Flash Hider Causing Accuracy Issues

BCD 45

Member
Hello shooters,
Maybe you can shed some light on this subject. I had my 18" predator profile barrel threaded. Without the flash hider, it will shoot 52 gr. bullets .500-.700. With the Smith Vortex flash hider & crush washer, put on snug but not tight, groups are 1.00-1.25 with some flyers make it 2.00". Take it off, put on the threaded cap snug, back to .500-.700 with no flyers. I've heard of muzzle brakes put on tight causing barrel stress but this is just enough where it won't shoot loose. I can't imagine it making a difference, but it's a 204 Ruger. It just PMO & stumps me. I've got 223's with a Smith Vortex without this headache. Any comments would be welcome. If your comment is sht can it, I've alredy thought of that.

Jim D
 
Hanging anything off the end of your barrel can change thing dramatically. It sometimes comes down to just the fact of the device is not playing nice with the rifle. I'd try going tighter, just to see. Also, see if Smith will send you another one to try out...it may just be out of spec in some way or another.
 

There was a post recently about barrel vibration and as you can imagine the END of the barrel moves the most. lt sounds like the flash hider being loose is creating some adverse barrel harmonics affecting accuracy.

I run QD flash hiders on all of my rigs for a suppressor and they get installed at 20 ft/lbs without a crush washer using a barrel vise. If using a crush washer the flared side goes against the barrel shoulder.

http://www.itstactical.com/warcom/firearms/diy-ar-15-build-flash-hider-installation/

 
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Originally Posted By: arlaunchWhat was your reasoning behind putting it on "snug, but not tight"

This is interesting.

he said
Originally Posted By: Texas Swifty I've heard of muzzle brakes put on tight causing barrel stress

i read that some place too. but i don't remember reading the cure was to put it on snug, but not tight.
if it was my rifle i would leave it off.
 
Was the barrel threaded concentric to the bore by the gunsmith? Do you have another muzzle device to thread on there to see if it changes anything?
 
Sorry guys, I been away a couple days. In answer to the questions:

1. I've read reviews that if you torque it on tight it will cause barrel stress & accuracy issues.
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2. That's what I've done, just shoot it with the threaded cap.
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3. JBO, I've just had a cheap 6.00 bird cage to try & it shot fine with it. My buddy is a 40 year machinist & has his own machine shop. He does work for Boeing & some other huge companies. He turned my barrel down in front of the GB from a varmint contour to a predator contour to shave off weight & he threaded it at that time. Yes sir, it's perfectly concentric to the bore.

It's very hard to tell, but I'm thinking one of the 3 prongs on the Vortex is bent either slightly in or out causing pressure on the bullet when it leaves the barrel. That's all my mind can think of. Thanks guys,

JD
 
Originally Posted By: Texas SwiftyIt's very hard to tell, but I'm thinking one of the 3 prongs on the Vortex is bent either slightly in or out causing pressure on the bullet when it leaves the barrel. That's all my mind can think of. Thanks guys,

JD

the buddy with machine shop should be able to tell you if it is a bent prong in about 60 seconds.
 
If you had the barrel turned down, that could be your problem. You didn't mention that in the first post.
 
yeah, turning down the barrel is a huge change. try putting the thread protector back on & see if it still has the accuracy it had before doing that. That will at least indicate if the change to the flash hider is contributing.
 
Originally Posted By: Texas SwiftySorry guys, I been away a couple days. In answer to the questions:

1. I've read reviews that if you torque it on tight it will cause barrel stress & accuracy issues.
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JD

I would tighten the Flash Hider down and check for accuracy. If you don't put enough torque on it to crush the "crush" washer then you are defeating it's intended purpose. You should be able to feel it flex as you tighten it.

I can't imagine 20 ft/lbs is going to stress a steel barrel when max torque on an AR barrel nut is 80 ft/lbs on an aluminum upper.

Put it in a barrel vise just behind the threads and the only stress point is between the threads and the barrel shoulder during the install. Once you feel the washer flex just take it to 15 ft/lbs if that makes you more comfortable.

 
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Originally Posted By: reb8600If you had the barrel turned down, that could be your problem. You didn't mention that in the first post.

Originally Posted By: Stu Farishyeah, turning down the barrel is a huge change. try putting the thread protector back on & see if it still has the accuracy it had before doing that. That will at least indicate if the change to the flash hider is contributing.


Uh...guys...?


Originally Posted By: Texas Swifty Take it off, put on the threaded cap snug, back to .500-.700 with no flyers.
Jim D
 
I believe the muzzle break is acting like a tuner. Put some spacers (.001 at a time) of different size between crush washer and the barrel. That will make the muzzle break seat at a different location and perhaps change the group size.
 
Got you pysco, I understand well.

Thank all of you guys, a bunch!

I haven't been able to go shoot lately but I'll let you know.

Jim D
 
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