u/Connect-Stress4215

I was having trouble getting my newest build to run with the ARC fire. It was going standard semi auto in both fire positions. Luckily I came across one of bb9’s recent posts where he used the borebuddy/mcmaster carr (P/N: 99040A408) ARC fire shim (.008” of advance on the cam) and that got him running. I cut a cardboard shim out of an ammo box (.015” thick) because I’m impatient and wanted to know what my fire rate looks like. As you can see, advancing the timing on the lever is definitely the fix, but I highly recommend just getting the proper .008” shim instead of relying on cardboard. The excess thickness of my cardboard shim makes the selector a little stiff going to the 3rd position.