gnappi Posted October 6, 2021 Share Posted October 6, 2021 (edited) I have a threaded .357 Sig barrel for my 5" M&P and got a steel comp got it. It's effect is remarkable. Follow up shots are faster now. Due to the comp weight, porting or both? Dunno, don't care it works pretty good. The comp is slab sided so I had to drill and tap the sides for setscrews to index it correctly. I've ordered some brass Allen setscrews (First time ever Ace hardware did not have what I needed) and I'm wondering if anyone has tried using a piece of lead shotgun shot in the hole to keep from buggering up the threads on the barrel with the setscrew? Or will the brass setscrews be sufficient? Other ideas? Aluminum ? Here's the comp before tapping the holes. PS, I thought about heat and the lead shot but I don't think the bbl will get that hot? Edited October 6, 2021 by gnappi Link to comment Share on other sites More sharing options...
Braxton1 Posted October 6, 2021 Share Posted October 6, 2021 I am wondering if that comp isn't 90-degrees off.... I have never seen a comp with ports on the bottom. They usually don't have those because it'd contribute to more muzzle rise and would kick up a heckuva dust cloud when shooting from prone. I have seen comps that only ported out of the sides; that's why I guessed "90-degrees off"..... Any of the setscrew ideas that you presented would work, but I've gotten to where I just glue them on. Loctite 271 usually works well. I use 640 Sleeve & Bearing Retainer. About the only commonly-used flavor that wouldn't work is blue Loctite. Link to comment Share on other sites More sharing options...
Nolan Posted October 6, 2021 Share Posted October 6, 2021 I agree with Braxton1. I think that comp is for a PCC similar to this 9mm SJC brake. It may work better rotated 90 degrees. Nolan Link to comment Share on other sites More sharing options...
gnappi Posted October 6, 2021 Author Share Posted October 6, 2021 (edited) Actually, UR both right, it's a modified "tanker" style and it's profile would interfere with the front sight as it is in the pic. I took the pic with the crush washer on after I tested it before drilling and tapping. Edited October 6, 2021 by gnappi Link to comment Share on other sites More sharing options...
Sinister4 Posted October 6, 2021 Share Posted October 6, 2021 (edited) you can get soft ended setscrews from mc master carr, they have brass tips on them. another way to to drill through the threads to form a pocket the screw sets in them run a tap through it to clear the threads, then chase the barrel threads in the lathe (or use a thread file) thats what I usually do, it will lock it solid in one position and you can locktite the screw they also sell shim packs to index the comps as well Edited October 6, 2021 by Sinister4 Link to comment Share on other sites More sharing options...
gnappi Posted October 6, 2021 Author Share Posted October 6, 2021 1 hour ago, Sinister4 said: you can get soft ended setscrews from mc master carr, they have brass tips on them. another way to to drill through the threads to form a pocket the screw sets in them run a tap through it to clear the threads, then chase the barrel threads in the lathe (or use a thread file) thats what I usually do, it will lock it solid in one position and you can locktite the screw they also sell shim packs to index the comps as well If you mean drill the threads on the barrel OD to form a pocket, I like that idea! Afterward I'd simply have to run my 1/2-28 die over the barrel threads to clean them up and locktite the brass setscrews in place. Thanks for the idea! Link to comment Share on other sites More sharing options...
Toolguy Posted October 6, 2021 Share Posted October 6, 2021 Drilling a drill point in the threads is the way to go. I would go with steel setscrews so the hex doesn't wallow out. Brass is very soft. When you make a drill point for the end of the setscrew, it won't mess up the threads. You do need to Loctite the setscrew(s). Also, it will always go back on to the same position every time if you take it off for any reason. Link to comment Share on other sites More sharing options...
MikeBurgess Posted October 6, 2021 Share Posted October 6, 2021 the solution that is the easiest is to just loctite the comp to the barrel threads. Yes you will have to clean the barrel with it still in the slide but thats not big deal it really isn't even a small deal. clean everything super well with solvent get it dry and perfectly clean, apply the loctite screw it on till its where you want it and let it sit over night. use red or better yet green loctite and you will be set for a long time Link to comment Share on other sites More sharing options...
MikeBurgess Posted October 6, 2021 Share Posted October 6, 2021 4 hours ago, gnappi said: If you mean drill the threads on the barrel OD to form a pocket, I like that idea! Afterward I'd simply have to run my 1/2-28 die over the barrel threads to clean them up and locktite the brass setscrews in place. Thanks for the idea! the brass setscrew is likely a bad idea and you will end up stripping its socket and having to drill it out. Link to comment Share on other sites More sharing options...
Toolguy Posted October 6, 2021 Share Posted October 6, 2021 (edited) To Loctite a comp to the threads, the best one I have found is 620 green. Use plenty on both threads, inside and out, and wipe off the excess. Edited October 6, 2021 by Toolguy Link to comment Share on other sites More sharing options...
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