I tried a bunch of 6-40s for Sig PRO slides, and found these to be the best overall (scroll down for the right size).
https://www.brownells.com/gunsmith-t...prod41830.aspx
You guys using the McMaster hardware, have you seen any trouble threading them? They are very tight on my M&P, and when I back them out there's noticable wear on the screw threads and a "ribbon" of material that I believe is from the screw itself. I've already sheared one in a slide, I'm a little wary of switching out my others. The hardware sent with my CHPWS plate does the same thing but the hardware from my Holosun and included from S&W threads easily and smoothly. Any ideas?
It looks like it's flattening or dulling the threads
Last edited by MD7305; 12-09-2020 at 03:22 PM. Reason: Pic added
Yes, it was a McMaster torx drive. They thread into my slide very tightly and leave wear on the threads of the screw to the point I'm leary of attempting to fully thread them in. I have two M2.0 compacts and it's the same situation with both. They become very tight before even coming close to even seating into my Holosun/CHPWS plate. Any ideas about what's attributing to this? After breaking one I'm very nervous about doing it again. The Holosun and S&W hardware threads into the slide without issue.
How did it break? What did the screw look like. What part was left in the slide?
Was it during shooting or installation? Did you tighten to a specific torque spec?
I ask because if there is a problem I want to deal with it and make things better, but details matter. Wear happens with friction between metal parts. Friction can mean intolerance or tight tolerance. Friction helps things stay in place. Poor tolerance can increase wear, but torsion force (a tight screw that has lots of friction) dissipates quickly when that force is no longer applied... so it’s important to have as much detail as possible to diagnose a problem.
It broke while I was installing my CHPWS plate along with the new McMaster hardware. The screw was about halfway threaded in, the screw head wasn't touching the Holosun yet. I noticed it was becoming tighter, at that point I should've stopped, but I continued tightening and it broke. I hadn't used my torque wrench at that point because the screw wasn't seated yet. That's totally my fault but I noticed that when threading the screws in my other slide there was flattening on the edge of the threads of the hardware. I was curious if that was normal or something you guys had experienced.
The first half of screw threads remain in the slide, with about 1/8" protruding from the top of the optic cut.
The hex hardware included with my CHPWS plate also was difficult to thread. Could the threads in my slides be out of spec? Could it be a tolerance stacking issue due to the slide apparently being finished after they were tapped/threaded? This is the case for both slides.
Hard to give a definitive answer without running a go/nogo gauge on the threads. Occam’ s razor says it’s probably a combination of finish and thread tolerance, but without data that is just an educated guess.
You could get thee to a gunsmith and have him gauge them, and if needed chase those threads with a tap.