Having issues with shims for timing mds. Help plz :)

Len5E1

Private
Minuteman
May 3, 2018
83
14
Hey there. So I don’t know what I’m doing wrong all of a sudden. I’ve timed several muzzle devices in the past for my suppressors and never recal having any problems but lately I feel like it’s always a problem. So what’s happening is the shims are smashing easily and either bending over each other or into the muzzle device a bit. Here’s the two examples:

1) Keymo devices. These seem to have a slight taper near the threads which makes less of a face for the shims to contact. So when I try to torque to spec the shims will actually bend into this taper area and get ruined.

2) I just tried timing 5/8x24 Surefire md using the shims it came with. The Surefire also has a sort of thin face to it where it contacts the shims but no taper so it’s not as bad but when I tried timing it to get it to spec the shims bent right over each other. Part of this I think is because while torquing it’s impossible to keep multiple shims perfectly centered up, they like to sit off center. I feel if I only had to use 1 shim it would be ok but my Surefire devices are horribly timed with my criterion barrel and requires 3/4 turn to get to 12 o’clock which is several shims.

I have accuwashers coming today which I hope will solve my problems but I still want some feedback as it was very frustrating feeling like an idiot not able to time some basic muzzle devices without shims getting ruined as soon as I pass 25 ft. Lbs.
 
I find that putting the barrel in a vertical orientation when installing the SureFire MD helps keep the shims lined up and prevents bending them.

No experience with Keymo.
 
Look at the shoulder of the muzzle threads to see if it has a relief or undercut ("C" in the image below). If not, you may have to use a beveled or chamfered spacer. Accu-Washers may work but you might have to chamfer them yourself.

TBAC_Centerfire_Rifle_Thread_Guide.jpg