So my “new to me” midlength AR showed up in the mail yesterday (previous owner had it built but it was unfired) and, pleased as punch, posted a few pictures here – it was pointed out by another member that the crush washer has been installed backwards. Is there any real problem leaving it this way other than potentially having the FH loosen up? Gunsmiths around here with proper AR tools are scarce, and I don’t want to risk messing up the FH or barrel if I don’t need to. My intended use is only competition against paper targets.
It probably won’t loosen up if it was torqued with enough weight, but I wouldn’t trust someone who put a crush washer on backwards to torque it right, either.
It’s not hard to do yourself, and in many cases (especially if it was installed backwards), there is adequate “life” in the crush washer to use it again, and torque it on. The torque is pretty broad for an FH, but the safest way is to turn at 1/8 turns, back it off, and turn again until it times it correctly.
Crush washers are flared and “crush” when squeezed, so the crushing tension keeps the FH on your barrel. The “life” is gone when the crush washer eventually looks like a regular flat washer.
Good luck, but you can definitely do it yourself if you’re patient and go slow. I’ve probably installed 30 muzzle devices in the last month…
Crush washers do not have a torque value. I would acquire another (just in case) and then make it right. You can do it yourself with a decent wrench.
You aren’t alone, if that consoles you at all. I had one come to my armory with a backwards crush washer and an upside down FH.