Probably An Unusual Barrel Cant Question

[Nick B]

I bought this 625-3 NIB from a collector about 10 years ago . When purchased the barrel was straight but now after about 800 rounds it's canted as if the barrel tightened itself. Is this possible ?
The rear sight is now cranked all the way over to the left side to get POI centered at 10 yards .

 

[Protocall_Design]

It must be possible, since it happened. An easy fix would be to remove the barrel, put blue Loctite on the threads and screw it back on, properly indexed. By the next day (or sooner) it will be firmly held in place.

 

[Scharfschuetzer]

Interesting. Probably the torque applied to the barrel from the bullet entering the rifling.

 

[AlHunt]

There doesn't seem to be another explanation. It does suggest maybe not all canted barrels left the factory that way.

 

[nicky4968]

I had a Luger that did the same thing. Instead of locktite I used lead foil wrapped around the threads.

 

[bobbyd]

I had a Colt Python that unscrewed the barrel every 2-300 rounds.
Definitely a real world phenomenon if barrel shoulder is not fitted well to the frame.
Funny thing is, that in the olden days when fixed sights were the standard, intentionally adding a little cant one way or the other was an accepted method in zeroing the gun.

 

[Goblin]

I had a Colt Python that unscrewed the barrel every 2-300 rounds.
Definitely a real world phenomenon if barrel shoulder is not fitted well to the frame.

One might wonder if you could drill a hole through the frame and a portion of the barrel and drive in a fitted pin to hold it in place.

 

[WR Moore]

The pin, or at least the way they used to be fitted, allow a rather startling amount of rotation before they interfere.

And yes, torque reaction of the barrel to rotating the bullet will tend to tighten a S&W barrel (and the Colt left hand twist to loosen), but it does require a barrel that didn't have proper torque in installation.

There have been a couple of threads on here, and some old gunsmithing books, that suggest slightly peening the shoulder of the barrel (out of the gun) or putting prick punch marks on the frame shoulder (guess you could do that to the barrel shoulder) to provide a smidgen of extra metal to try to get correct torque. Either method depends upon exactly how much metal needs to be added to the barrel shoulder. My semi-educated guess (been too long since I was doing barrels) is that it's more than you're likely to get through either method.

I'd be reluctant to use thread lockers. You might try checking with S&W to see if they can/will help you out. Setting the barrel back would really be the right way to do it, but can be costly depending. Don't know any 'smiths in Florida.

 

[Protocall_Design]

I've done the blue Loctite method a few times and it works very well. With blue, you don't have to heat anything to remove the parts. I don't recommend anything unless I know it will work.

 

[WR Moore]

I've used thread lockers/stud & bearing fasteners and I don't doubt it'll hold. But, how much you use and if you got everything chemically clean seems to make a difference on how firmly they hold. I've had use (low) heat on a couple of assemblies that were blue Loc-Tited. There's a transmission shifter fork I used blue on that isn't ever gonna move without heat. I used the Loc-Tite to sleeve the fork on the rail.

 

[Jerry M]

I believe that there was a gun writer who pointed this out this problem when the barrel pins on S&W's were omitted from the barrels.

 

[BigBill]

Why the removable blue loctite? The forever red loctite would never loosen again. To me if the barrel is coming loose it's past being fitted. You can't torque it enough to hold its alignment in the proper position. If this is correct I'd go with the red loctite.

 

[stansdds]

The only issue I see in using red Loctite is if something happens to the barrel and it has to be replaced or someone decides to do a barrel swap.

 

[Racer X]

The only issue I see in using red Loctite is if something happens to the barrel and it has to be replaced or someone decides to do a barrel swap.

Red lets go at about 400F Just use a heat gun, and problem solved.

 

[WR Moore]

All the red Loc-Tites aren't the same, you might want to read the manufacturers directions on whatever you bought before betting on that. Or, using the product code, check the Loc-Tite website. I had to do that a couple of years back and got boggled at the many different products, some of which share a color, but not necessarily all the properties. I know I've got a red product with a 500 F release.

 

[teletech]

Yes, a thread locking compound (Loctite, etc.) will work.
I wouldn't worry about using red, that amount of heat won't hurt anything should you decide you need to replace the barrel.
I can also vouch for the peening method as effective. It's surprising how much metal will move if you hit it with a hammer and those barrels aren't really all that hard. It's easy to have it look lumpy though, so go slow and gentle if you try it. Also use the smoothest hammer and anvil surface you can find since surface imperfections will transfer readily.

As for alignment: you can just do it by eye, but it's a lot easier if you get two parallel bars and carefully balance one on the rear sight of top of the frame and the other on the front sight base someplace, then stand back a bit and look at them in the same plane. It's surprising how close you can get them just by-eye.

 

[Nick B]

Thanks for all of the replies. I'll probably just send the pic to S&W and see what they say. Besides aligning the sights I'd like to have the cylinder gap tightened up .

 

[luvsmiths]

Thanks for all of the replies. I'll probably just send the pic to S&W and see what they say. Besides aligning the sights I'd like to have the cylinder gap tightened up .

Thats the way to go. And if it needs anything, send it back to them and let them do it.