Barrel install Question on an N frame

[pred]

I have a 629 where the barrel rotated about 2*, in the tighten direction ,,So the sights are thrown off, I was getting ready to call S&W on monday since the gun is from 89' I figure that they will honor the warrenty.
Since it was bugging me to no end, and was home with no errands to run today, I fashoned some wood for the vice, and I have the old style wooden clamps that you had in wood shop, Notched it out to hold the frame and gave it a tap or two and loosened the barrel the 2* to be straight... Now I am thinking that it will only tighten again, DO I take it off, clean all threads and put a drop of locktite on it and reinstall??
Send it to S&W and miss my 629?
When this happens, what does a good gun smith do?
Do they machine the barrel, and get it to turn in 1 more time, then file the forcing cone>??
Do they have a really thin crush shim and set it back to where it was?
Or do they just use a drop of locktite?
OR dimple the frame or barrel to (stretch) the metal??
I know,, I am a PITA at times ,,,
But you guys are so darn good!!!
Thank you
Peter.

 

[pred]

I have a 629 where the barrel rotated about 2*, in the tighten direction ,,So the sights are thrown off, I was getting ready to call S&W on monday since the gun is from 89' I figure that they will honor the warrenty.
Since it was bugging me to no end, and was home with no errands to run today, I fashoned some wood for the vice, and I have the old style wooden clamps that you had in wood shop, Notched it out to hold the frame and gave it a tap or two and loosened the barrel the 2* to be straight... Now I am thinking that it will only tighten again, DO I take it off, clean all threads and put a drop of locktite on it and reinstall??
Send it to S&W and miss my 629?
When this happens, what does a good gun smith do?
Do they machine the barrel, and get it to turn in 1 more time, then file the forcing cone>??
Do they have a really thin crush shim and set it back to where it was?
Or do they just use a drop of locktite?
OR dimple the frame or barrel to (stretch) the metal??
I know,, I am a PITA at times ,,,
But you guys are so darn good!!!
Thank you
Peter.

 

[Joni_Lynn]

One thing I'm certain of, don't dimple the frame, it would possibly create a weak spot that might crack later on.

 

[BruceM]

If you haven't twisted the frame already, have the barrel re-installed professionally. The barrel is, to some extent, "crush fit" although that is really a misnomer. I'd forget the lock-tite. Also, if you had left it alone, warranty work would probably have been a non-issue but since it has been shade tree gunsmithed...................

Bruce

 

[robertrwalsh]

Once you loosen the barrel it won't stay put. What will have to be done is relieve the surface where it mates against the frame to where you can hand tighten it to about 1/8 turn or a little more from being in the correct position and then turn it with the wrench into position. (Hard core target guns they use more like 1/4 turn) Using a shim would work (probably-maybe) but it wouldn't look right. Then,unless the b/c gap was excessive to begin with, the forcing cone would have to be re-cut and trued up. Theoretically this can all be done with hand tools but relieving the end of the barrel is a bitch with a file. Pay a pro and get it done right.

 

[john traveler]

Pred, since you took the time and effort to make barrel blocks and frame vice blocks, you did good.

That 2 degrees of misalignment translates to a very teeny tiny compression of the barrel shoulder, almost not enough to worry about.

The rule of thumb when fitting up a barrel to the frame is to allow the barrel shoulder to touch the frame and still need approximately 1/8 turn or "draw" to full alignment. Your barrel movement amounted to 2/60th of a turn. The amount that you loosened the barrel should not matter. Firing vibration from the rifling torque will LOOSEN, not tighten the barrel.

I would suggest firing the gun to see how the sight alignment holds up. It it does not, my repair would be to use a brass hammer and peen the barrel shoulder evenly to generate more than 1/8 turn draw.

 

[tomcatt51]

Shoot it. If it moves, LocTite it. Occaisionally you'll see a S&W revolver barrel with a visible jog in the rifleing at the barrel face from over-torqueing the barrel. Ruger likes to put too tight a crush on the barrel threads and creates a constriction where the barrel is threaded into the frame. Neither is good for accuracy. Less barrel torque and LocTite works just fine. You can do no harm this way.

 

[pred]

Brucem, There would be no way to tell I clamped it up in some hard wood,,,, I am not worried about warrenty, But I cant see why they wouldnt, ..................................................................SO what I understand it that if the barrel is a tad over tight direction it is not from bullets torquing it that way,,, Bullet torque will loosen the barrel.
Is this a correct statement? I am at work and dont have a gun on me, In NJ today,
Thanks all!
Peter

 

[pownal55]

now i know why i like pinned barrels.

 

[pred]

OK, got home early, Looking at the rifeling I would say that shooting the gun would indeed tighten the barrel.
I took the time to pull the barrel and wound it in hand tight, I was 1/8" to 3/16th" off center, I did take the time to clean the threads on the barrel and frame, I used 1 drop of red Locktite on the threads and wound back in, and snugged into perfect alignment, It all went well, If I were to guess from years of turning wrenches, I would guess 15-20 FT LBS in straight,
On the down side,,,,, I wont have time to shoot it a bunch until next weekend which is a downer to me,,,, This 629 is a woods gun only to be carried a few times a year, So it wont get too much use,,,, I will update when I can run 25-50 full house loads through it.
I am hoping that it will be fine!
Peter.

 

[pred]

Thanks for the reassurace!
I have pulled heads on my cars, lapped valves, built custom tools ect, I didnt believe that if I looked at the 629 funny I would bend the frame,,, Now that it is done, and simply at that, I can see that sticking a hammer handle through the window is NOT a great idea.
I wiped the gun down before the clamping and after,,, I cant see the slightest evidence that it was even handeled.
I want to swap barrels on a J frame, But am hesitant,,,, SHould I BE?????
Peter

 

[WR Moore]

This advice is worth what you've paid for it

Back in the day, I rebarreled a goodly number of S&Ws. I noticed with the adjustable sight guns that there was a 'standard fit' on the factory barrel. Basically, the barrel would free turn until the leading (left edge from the rear) edge of the barrel rib would align with the near (or right edge) of the rear sight cut. At this point the barrel was hand tight. Turning the barrel to proper alignment produced the proper torque. A wee bit of grease on the frame/barrel faces makes things easier.

BTW- this was with the pinned barrels. Frankly, given the torque to achieve alignment, the pins were cosmetic only.

I made sure to use the same radial measurement on custom barrels and never had any problems.

 

[pownal55]

i am not questioning your experience but if pins in barrels were cosmetic, than why does the unpinned barrel, on rare occurance move?

 

[john traveler]

pred,
Your M629 has right-hand twist rifling, just like mine. If you looke at the rifling from the forcing cone (breech) end of the barrel, you will see that bullet firing will torque the barrel anticlockwise (looking at the muzzle end). That means firing tends to loosen the barrel.

That estimated 15-20 lb-ft of barrel torque puts it at the bottom limit of acceptible. The red locktite will probably do the trick.

In answer to your question of whether to attempt to rebarrel the J frame, I would advise "NO". The smaller frame guns have much less material to resist frame distortion and overtorquing. You will notice that the majority of reports of cracked frames involve J and alloy frames. The most susceptible combination for damage is a J Airweight frame. I would leave those for the S&W factory.

In response to pownal55's question: In S&W's long and glorious production history, pinned revolvers were made at a slower rate and with more attention and care to their assembly. With today's workforce almost totally lacking in S&W "old timers", it is all too easy to find revolvers overtorqued, undertorqued, and slipped past quality control inspectors. If you have ever removed and replaced as many barrels as we have, you will find that most barrel crosspins do not prevent absolute lateral movement of the barrel shank. It only limits it to prevent unscrewing of the barrel.

 

[pred]

John,,,, I am confused now,,,, Looking from forcing cone forward, The rifeling goes to the right,,,, Which means that the barrel would torque to the left (anticlockwise) as you say, But that would be the Tighten direction,,,
Anticlockwise from the rear of threads=clockwise from front of threads,,,,
WHich would tighten from lots of shooting through an improperly tightened barrel.
Peter.

 

[john traveler]

Negative. Bullet twists to the right to follow the rifling. Barrel also twists (torques) to the right when viewed from the breech. Looking at the muzzle end, these same motions equals anticlockwise motion of bullet and barrel, which means the barrel tries to unscrew from the frame. If it were free to do so from lack of a crosspin or inadequate installation torque, it would.

 

[Bullseye Smith]

John is right pred, but I think you should be OK with the lock tite on it. Shoot it and find out.

 

[WR Moore]

Originally posted by john traveler:
Negative. Bullet twists to the right to follow the rifling. Barrel also twists (torques) to the right when viewed from the breech.

Newton: "For every action, there is an equal AND OPPOSITE reaction." If the bullet is forced to the right (clockwise from the rear), the reaction of the rifled barrel will be opposite/counterclockwise, tending to tighten the S&W barrel.

If you want another example, find a pickup truck and check the rotation of the engine. Then fire then engine up, goose the throttle and see which way the engine reacts.

As to barrels moving, Johns right, the pins do allow limited movement. The pins were (probably) a marketing response to the issues Colt had with their left hand rifling actually unscrewing the barrels.

 

[pred]

SO>>>> TIGHTEN-OR-LOOSEN><><><><><>
I would think tighten as I have posted, How could the barrel have been over tightend?
Equal and opposite reaction,,,,
That's what I meant to say.
Has anyone had a barrel unscrew from shooting?
Peter.

 

[Rancher]

If the barrel were not rifled, the bullet would travel down the bore in a straight line, due to the inertial force. With a right-hand twist (clockwise, viewed from the rear), the bullet follows the rifling and spins to the right, but thus creates a force that attempts to twist the barrel to the left (counterclockwise, again, viewed from the rear). Twisting the barrel to the left or counterclockwise when viewed from the rear is the direction of tightening the barrel into the frame for right hand twist threads.