Overtorquing flash hider

[JediGuy]

After being quite proud of myself for completing 100% of my lower myself (and wife for the bolt catch) and the barrel/rail installation without a scratch or hiccup... I believe I overtorqued my flash hider on the nice, brand new BRT barrel (sorry). The flash hider is an A2 from Anderson; I’m sure that was my first mistake, but I wanted to keep this basic the muzzle device simple, and of all things, I didn’t think an inexpensive flash hider would make a difference.

I used a torque wrench and thoroughly coated the threads in Aeroshell, but missed the 20# click, instead focusing on ‘getting it aligned.’ I know I went well over 20#. Probably about 270 degrees of rotation with resistance.

Initially, I approached this as “what the heck, my mistake, hopefully it doesn’t affect much” but then did some reading on here and decided to pull off the flash hider (it came off very easily). Now the crush washer is deformed enough to not come off easily, so I’ve read a couple old threads on how to go about that.

My question: How screwed am I? I don’t know how many # of torque were applied, though I can’t imagine it was super high; a standard torque wrench was used, so not super long or anything. Is this going to cause permanent and/or noticable damage to the barrel? The goal was for this to be a compact precision gun rather than for speed shooting.

[bp7178]

Don't use a crush washer on a precision build. They can negatively effect the alignment of the muzzle device. This is why they are not recommended for use with suppressors. Use shims or a flash hider you don't have to lineup, ie Smith Vortex.

A shit muzzle device can have a big impact on accuracy.

The only thing you can do is shoot it and see how it goes. Odds are it will be fine.

[26 Inf]

After being quite proud of myself for completing 100% of my lower myself (and wife for the bolt catch) and the barrel/rail installation without a scratch or hiccup... I believe I overtorqued my flash hider on the nice, brand new BRT barrel (sorry). The flash hider is an A2 from Anderson; I’m sure that was my first mistake, but I wanted to keep this basic the muzzle device simple, and of all things, I didn’t think an inexpensive flash hider would make a difference.

I used a torque wrench and thoroughly coated the threads in Aeroshell, but missed the 20# click, instead focusing on ‘getting it aligned.’ I know I went well over 20#. Probably about 270 degrees of rotation with resistance.

Initially, I approached this as “what the heck, my mistake, hopefully it doesn’t affect much” but then did some reading on here and decided to pull off the flash hider (it came off very easily). Now the crush washer is deformed enough to not come off easily, so I’ve read a couple old threads on how to go about that.

My question: How screwed am I? I don’t know how many # of torque were applied, though I can’t imagine it was super high; a standard torque wrench was used, so not super long or anything. Is this going to cause permanent and/or noticable damage to the barrel? The goal was for this to be a compact precision gun rather than for speed shooting.

Crush washers are called 'constant torque washers' in the Colt Canada Armorer's Manual and 'recessed washer' in the TM. The range of movement is 90 degrees minimum to 450 degrees maximum (1/4 to 1 1/4 turns).

So you didn't over torque yours. ETA: Both the Colt Canada and the TM noted there is no torque specification. Apparently the torque doesn't vary much betweein 90 and 450 degrees.

I use this shim kit: https://www.brownells.com/rifle-parts/barrel-parts/rifle-barrel-hardware/washers/ar-15-223-shim-set-prod38890.aspx

and Rocksett: http://www.flexbar.com/shop/pc/ROCKSETT-2-OZ-p4019.htm

[rjacobs]

yea I didnt think there was a torque spec for the A2 with a crush washer either.

I didnt know the actual spec as 26 INF posted, but I knew it was more than 1 turn past touching.

[HeruMew]

After my most recent run in with a 7.62 A2 Hider and a crush washer needed to be "threaded" off after, I will never use them again.

[markm]

Your arm should tell you when things are being cranked to tight in any mechanical situation. I would guess that if you didn't have to really "bear down" on the FH, you're fine.

[Clint]

This can happen with some of the cheaper crush washers, where they deform too much and get captured behind the threads.

[JediGuy]

Thanks for the responses, all.

I ordered a shim kit (and one in 1/2-28, since I like to learn things like this once) and a LaRue A2 FH.

Appreciate the reassurances on the barrel...not really worried about the washer, as that seems easy enough to dremel/cut off with basic tools. Just won’t be able to get to it until next weekend. We’ll see sometime the weekend after if I can make it shoot...

[opngrnd]

Op-Which barrel did you buy? The stainless one?

[100]

I had an upper that I purchased new that came with the standard A2 flash hider. I wanted to change it out for a Phantom and it was hard as hell to get off. I have those barrel vise jaws that Bushmaster sells and the barrel kept rotating in the jaws, no matter how hard I tightened the vise. I ended up getting so pissed and tightened the vise so much that I bent the vise handle. Even then removing the flash hider was a bitch. Eventually I got the Phantom on took it to the range for the 1st time. I couldn't keep my groups on a pie plate at 25 yards, that is how bad the accuracy was. I'm not sure if it was a defect in the barrel that caused this, or perhaps the overtightening of the A2 hider from whoever assembled the upper.

[Hmac]

You can't overtorque a crush washer. The torque stays the same as it crushes, until it completely crushes. The whole idea is to just turn it until it's indexed. Very simple device, pretty much a no-brainer. You didn't damage anything except the crush washer, which is, what....$.75. I've never used anything except crush washers for years to install a muzzle device. Shims are a PITA. Maybe a preferable route for a precision build but I wouldn't know...I've never striven for precision exactly.

[JediGuy]

Op-Which barrel did you buy? The stainless one?

Yessir, I have the SPR stainless. Centerpiece of my Centurion build.
It’s not like the recoil on any 16” (or even my 12.5”) is actually bad, but I liked BRT’s gas design and profile. And, the barrel is undoubtedly more accurate than I am capable, so I also like the idea of a known good quality.
Kind of like learning on a Martin over a Yamaha; you don’t need to, but why not?

[markm]

You can't overtorque a crush washer. The torque stays the same as it crushes, until it completely crushes.

I'd bet that there are some garbage crush washers out there that don't meet this description. For A2 flash hiders, I use them too. I even re-use them when they've not been smooshed much.

I've installed so many shim devices that I dread that ass ache incredibly.

[Iraqgunz]

There is no torques value for an A2 styled flash hider. The manual clearly states it is based upon alignment.