I neglected to mention that this barrel is heavily dimpled. That being the case, wrapped in a heavy-duty cloth and clamped in the vise was enough to index the brake with the crush washer. Without the dimpling this would not have worked.
Thanks, all.
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I neglected to mention that this barrel is heavily dimpled. That being the case, wrapped in a heavy-duty cloth and clamped in the vise was enough to index the brake with the crush washer. Without the dimpling this would not have worked.
Thanks, all.
I guess, while this thread is active though, I'll go on and ask this:
If using a barrel clamp is the only recommended way to do this, that seems to mean that if you have a free-float rail installed, the whole assembly has to come off in order to change the brake the right way? Is that correct? Because leaving the rail on, the only way I could see doing it would be with the upper in an upper receiver vise block.
I guess it's true that if you don't have any exposed barrel at all, you'd have no choice but to remove that rail. I didn't have to do that on my 11.5 SBR with 9 inch rail when I installed the FSC556, however. Took me about 10 minutes to install the brake, and that's because it took me 5 minutes to find a 5/8 open end wrench. Likewise, no trouble installing Battlecomps on either of my other two rifles, both of which have 16 inch barrels.
http://mccollister.info/clamphere.jpg
You may have to cut down the barrel clamp pieces, as I did, to clear the rail, but its do-able.
mark
For what it's worth, when I install comps I always use an armorers wrench which allows the torque to be applied without side loading, or inducing off axis force, while applying rotational force. I've never had any issues using an action block.
Just an FYI. Rotation of 90 degrees (1/4 turn) will impose a crush distance of .0089" or about 3 strands of hair for the layman.
More importantly...what are the torque characteristics of a crush washer on a 1/2 x 28 thread? Once it begins to crush, does the torque stay constant? Or does the torque increase as it crushes?
I had always understood that 90-100 degrees gave the appropriate torque value - about 25 ft-lbs. Do you know if that's correct? I mean, it's how I've always done it except for the time I used shims on an FSC556, which came loose.