Effect of an over-torqued barrel

[1911Prof]

I’m trying to figure out the effect of an over torqued barrel on the point of impact of a revolver.  I understand the problems of the front sight not being vertical and the need to compensate with the rear sight, but I am uncertain as to if there is an effect on bullet trajectory other than sight alignment 

[PatJones]

My 627 has a front sight off to the left due to barrel clocking. I've adjusted the rear sight to the left to compensate. It shoots fine, there is no way you'll ever notice that the bullet trajectory is .020 off to the right.

[Alaskan454]

I have a 625 that was under torqued and it shoots fine to 100yds.  Obviously the rear sight is not centered though.

[MikeBurgess]

I have read online somewhere of severely over torqued barrels where the barrel is compressed at the threads in the frame causing that area of barrel to be slightly smaller than the rest, this supposedly causes some accuracy issues.  I am not sure but it may have been a K frame thing where the barrel is very thin at the threads, that said I have not seen it on any of my guns, it may just be internet lore 

 

 

[Toolguy]

I've seen lots of them in all frame sizes. This happens when the barrel is too far out of vertical when it first touches the frame, then they "crush fit" it to get it up to 12 o'clock. When it's over tightened like that it squeezes the bore down in the area just ahead of the forcing cone where it's threaded into the frame. I've seen them as much as .003 smaller than the rest of the bore. When that happens, the bullet passing through is also swaged to that size, then rattles down the rest of the barrel. This will cause significant leading if using lead bullets. Obviously accuracy suffers quite a bit.

 

All this has nothing to do with whether the front sight is vertical, or slightly off to one side or the other. That is a separate problem of the barrel not being installed carefully.

[MikeBurgess]

1 hour ago, Toolguy said:

I've seen lots of them in all frame sizes. This happens when the barrel is too far out of vertical when it first touches the frame, then they "crush fit" it to get it up to 12 o'clock. When it's over tightened like that it squeezes the bore down in the area just ahead of the forcing cone where it's threaded into the frame. I've seen them as much as .003 smaller than the rest of the bore. When that happens, the bullet passing through is also swaged to that size, then rattles down the rest of the barrel. This will cause significant leading if using lead bullets. Obviously accuracy suffers quite a bit.

 

All this has nothing to do with whether the front sight is vertical, or slightly off to one side or the other. That is a separate problem of the barrel not being installed carefully.

thank you, 

 

 

I hate it when I think I remember something but do not have the first hand knowledge to back it up.

[Alaskan454]

So I've never experienced thread choking in smaller bores, say up to .355 and .357.  But I have in bigger calibers like the .45s and .475s.  I guess I've been lucky thus far.  

[PatJones]

So I've never experienced thread choking in smaller bores, say up to .355 and .357.  But I have in bigger calibers like the .45s and .475s.  I guess I've been lucky thus far.  

I had a Colt Trooper MKIII, that had a constriction where the barrel passed thru the frame. Between that and the MKIII lockwork, I've never missed that gun once.