can barrel threads be crooked?

sniperman

hi people,i bought a webley and scot .22lr some weeks back,its very accurate until i put on a moderator (new sak) then its all over the place,me and a mate went to our local sand pit to try figure out whats wrong,he also has a .22 its a cz with an atec mod,tried that on mine,same thing will not group some shots evan miss the a4 size target, tried my mod on his,no issues,tried mine without mod,its spot on,he said the only thing he can think of is the threads on the barrel are somewhat crooked,it looks fine,is he right?should i have it re threaded?if so anyone know a good smith near me,im in nenagh/tipperary,opinions welcome,thanks..ps we both looked inside both mods for any signs of clipping,but could not see anything

Cass

The smallest contact between the bullet and the inside of mod can cause dramatic difference in POI (point of impact).

I had similar on a centrefire. Initial thoughts were the suppressor but i done as you did and tried another suppressor. Same results.

Stripped down the mod (thankfully I could) as much as it would. Couldn't see anything. Got out the borescope and on the last baffle on the inner side (not visible from the outside) was a "clean spot". I wouldn't class it as a nick or impact but the slightest of glances from the bullets.

Had the barrel rethreaded, threads on the suppressor checked, and all was good.

Factory rifle, with factory threading. The suppressor was an end of barrel, not over barrel, design so the imperfection was minute as the bullet traveled the full length without blowing out the side of the mod, but enough to cause scatter pattern results in POI.

I'd definitely have it checked out and a rethread shouldn't be more than a ton (haven't had work done in years so could be way off in my pricing).

sniperman

thanks for that cass....we thought of having the mod re drilled making the holes a tad bigger,what would be your thoughts on that?would it be dangerous,would it weaken the mod,make it louder,or would it evan work?

Cass

I done that with a mod I was giving to a friend. Not for any problems but because the mod I had was 6.5 and my mates rifle was 30 cal.

The internal baffles were 10-11mm but the crown of the suppressor was, iirc, 8.5-9mm. I drilled it out to the same diameter as the internal baffles, stuck it in the rifle and it worked.

I would NOT recommend drilling out the internal baffles, but to do as I done (the muzzle/crown of the mod was all i drilled out) so I had very little to no concerns about safety or structural soundness.

You may not need to go as large as i did.

Can the mod be stripped? If so strip it and use a calipers to measure the internal baffles. Check the diameter against the muzzle of the mod. This will tell you the width you can go to. No reason for that other than I'd not have the muzzle larger than it needs.

If you internal baffles are say 9mm and your muzzle 7mm then drill it out to 8. Check. If not enough try 9mm. If that still doesn't work then stop and get the rifle rethreaded.

It'll take about 10 minutes if you have the drill bits. So easier and quicker than a rethread. If it goes to crap, rethread, new mod and your sorted regardless.

sniperman

thanks cass for that............update,we drilled out the sak with a bit about 1/16 of an inch bigger,the whole way through,and by god it worked,grouping great now,might be an idea for anyone having same issues,thanks again

Cass

Happy days. Quick and easy, not to mention cheap, solution.

Grizzly 45

If you ever sell that gun,just let the new owner know about that little "kink" of it,or sell them the silencer with it.so they don't have the same problem in the future.

sniperman

https://www.boards.ie/discussion/comment/121298355#Comment_121298355

i will,but wont be selling it any time soon,way too accurate

delboythedub

https://www.boards.ie/discussion/2058319801/can-barrel-threads-be-crooked

If you think that the Mod is scored on the inside of baffles get a €3.00 chainsaw file and stick it in the top part of mod which should be lying on a flat surface like a table and roll the mod while gently working the file in and out AND DONT damage the threads