AR-15 flash suppressor tightenin


Dan Forrester
July 21, 2007, 06:58 PM
I picked up a matching LMT upper for my lower I purchased a couple months back and have a question about the flash suppressor. Before I fire any new gun I like to take it completely apart and clean before firing. Part of this disassembly is removing the flash suppressor which was properly aligned with the vents point up to counter act the muzzle clime. It was thought to get off with a crescent wrench due to the crush washer (I believe thatís the what they call them). Now I canít get it back on the muzzle tight enough for it to realign.

What do I need to do?

Thanks, Dan

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July 21, 2007, 07:17 PM
New crush washer maybe? Use a real wrench made to fit the FH properly, you'll be able to torque it down better. Crescent wrenches are garbage.

July 21, 2007, 07:19 PM
How are you securing the barrel while you are wrenching?

Dan Forrester
July 21, 2007, 07:35 PM
Thatís the problem, securing the barrel. How is one supposed to do this?

Also whatís the proper wrench?

Thanks for the responses guys.


July 21, 2007, 08:10 PM
Ideally, you want to put the barrel in a vise, use a GI M16 combo wrench or similar tool, and torque the flash suppressor to 15-20 ft-lbs. Don't overtighten, or you can end up constricting the bore.

July 21, 2007, 08:26 PM
Any quality 3/4" wrench will work. Oh, and buy a new crush washer, they aren't designed to be reused.

Dan Forrester
July 21, 2007, 08:41 PM
Any links on where to pick up the barrel vise and fresh crush washers. Are there any other washer options available? Is that armorerís (I know thatís spelt wrong) wrench considered the correct wrench?

Thanks, Dan

July 21, 2007, 09:02 PM
You don't need a barrel vice. It's only 15 ft lbs. Get two pieces of soft pine, clamp the barrel between them in a regular vice. Tighten it just enough that it won't turn, don't go trying to crush it.

You can get the crush washers from anyone who sells AR parts:

Are there any other washer options available?Yes, Peel Washers. You don't want them. They are a big PITA.

July 21, 2007, 11:00 PM
Put the barrel in the vice, not the front sight! Use soft pine as DMK said, and crank away. I have removed and installed 5 or 6 FH's, and sometimes you have to crank down on the vice. I have a 4" MAC Tool vice that I use.

July 22, 2007, 02:57 PM
According to AMU (Army Marksmanship Unit) specs, do not torque the flash hider. Get yourself some red Loctite and leave off the crush washer. Hand tighten the FH until properly timed, then allow to "set up" overnight. Torquing the FH onto the barrel stretches the barrel threads and screws up your barrel harmonics.

July 22, 2007, 10:51 PM
A crescent wrench is junk because they can easily back off, and round off whatever you are working on.

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