I’m getting my 2nd 10.5" LMT upper together and this dang flash hider is getting the best of me (won’t line up).
This is with the crush washer it came with (used upper/barrel)
It lines up but upside down…
New washer
This is hand tight; it’s already past 12 O’ clock. Not sure what to do other than ad like a shim washer?
If you’re using a crush washer, try crushing it. You can keep tightening those things like a full turn beyond where it first snugs up.
It’s a YHM crush washer but I don’t think it’ll make it another 1/4 turn let alone a full or half rotation…
I WILL try though.
Sounds like you’re using the crush washer wrong. Used correctly, it’s impossible NOT to be able to get it clocked correctly.
Screw it down finger-tight. You then have at least 360 degrees of rotation possible. You need at least 90 degrees of crush. Tighten-loosen-tighten-loosen until your a little over 90 degrees short of clocked, then go the full 90+ degrees clocked and stop. Don’t loosen once clocked. You’re done.
I know how it sounds but this is not my first rodeo.
Recap: old washer centers upside down, new washer clearly goes past centerby two slots when tight. I’m thinking of finding a thin shim washer to work with the new crush washer or maybe Teflon tape with new crush washer as a last resort.:mad:
follow this advice…
Alrighty then. This is the first time I’ve had one not within a 90degree turn of centering. So, should I use the old washer and try for a 180degree-to-center or the new washer and go ~340degrees?
I feel like I’m going to tweak my upper with that much torque…
A2 hider.
You are using an action block? If yes then turn it like the other posts say.
If you still cannot get it to index then you can use peel washers to make up the difference. However it really should index with a new crush washer as is.
No, I’m not using an action block. Once I get my gas block situated, I’ll try cranking on the A2 and see if I can get another 180 degrees and if that doesn’t work, I’ll look into a peel washer I guess?
If you have a vice you can make some wood blocks to clamp your barrel in and then crank the hell out of it. You will be surprised how far it will turn with the crush washer once you are able to put some torque to it.
That’s good idea. I’ll try that, thanks.
I too recommend the tighten, loosen, repeat method. Especially if you have a long way to go. I have gone too far too fast and had a crush washer crack.
If you think you need a shim to use with a crush washer then you don’t understand how to use a crush washer.
You can use a receiver block, but you’ll be much better off with a barrel block. You have to use something to secure it or you’ll never be able to get enough torque. Take a couple of 4-inch lengths of 2x4 if you have the room on the barrel, or 2x2’s if not, and cut a pair of matching V grooves across the grain. Slip an old bicycle innertube around the barrel, put the whole thing in a vise and clamp the barrel in the V-grooves tight just behind the end of the barrel.
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DO NOT USE AN ACTION BLOCK.
Clamp the barrel, not the action.
I understand the concept of a ‘crush’ washer, I just don’t think there’s room to ‘crush’ to where it needs to go but I’ll take the advice given; clamp the barrel down and try to get it there. Hopefully that’ll do it.
Thanks all.
These two statements are mutually exclusive.
No need to use shims with crush washers. Choose one or the other.
To make our lawyers happy, the following is NOT advice, and we assume no liability if you use it. We always encourage the use of a professional, EXPERIENCED AR gunsmith:
Use a barrel block.
The “flare” or bell portion of a crush washer flattens against the device, as it has a larger OD than the barrel shoulder. The bell OD is usually larger than the shoulder OD, so the washer will not want to crush. It is possible to put a crush washer on this way, which is backwards; and the washer might even crush a little, but not very well this way, if at all. Folks very often try this and then call us wondering why this doesn’t work.
Try a quarter turn at a time, and then back it off to crush the washer incrementally – instead of putting 140 lbs. of torque on your barrel threads all at once.
Final torque into position should be about 30-45 lbs.
We have also received calls from many alleged gunsmiths and engineers, so you’re not alone in this. Everyone has to start somewhere.
Sometimes, sanding the narrow end of the washer can help. You must sneak up on it, but this is my least preferred method, and I never actually use it myself.
Good luck!
I truly appreciate all of the advice and I’ll be using it tomorrow when I get a hold of my neighbor’s vise.
We have also received calls from alleged gunsmiths and engineers, so you’re not alone.
PRGGodfather, thanks for saying so as I’m feeling pretty foolish posting for help about a flash hider lol.
You need this from Brownells, or something similar.
Normally, I’d never pass up a chance to buy another tool, but the only time I’ve ever seen one of those $22 barrel clamps used it marred the barrel permanently, even with a line. I’ve never had that happen with the 2x4 pieces.