67-5 Barrel Turning in Frame

[Jade]

This week, I finished tuning my new (factory new from dealer) 67-5 that I am planning on using for IDPA SSR.

After finishing the internal work (polishing action parts, Miculek spring set, etc) I took it to the range for some accuracy testing. It placed reasonably nice groups with factory (UMC) ammunition, but my Rainier (158 gr .358 dia) handloads shot a 6" pattern. Back to the shop for cylinder work: ream chamber (Clymer), throat (Manson) and chamfer chamber mouths. I also cut and lapped the forcing cone to 11°.

Back to the range for another round of test firing, this time with more and varied ammo. Better groups with factory ammo. Way better groups with my Rainier reloads!

Tried some +P's as the gun is rated for +P. On the third cylinder (shots 13-18) the whole group moved 5 inches to the right!! Careful examination of the gun showed that the barrel has rotated several degrees clockwise (facing the muzzle). See pictures:

Personally, I want to simply adjust the barrel back to top center position, drill and pin it. Can anyone suggest a good gunsmith to do the work?

Failing that, I am thinking of simply loosening the barrel, applying some high temp lock tight and re-tightening it to top center position. I really don't want to go through the drama and cost of setting the barrel back one whole turn (.030"), recutting the cylinder gap and forcing cone, and shortening the extractor rod and center pin.

Or should I send it back to Smith and Wesson? Will they correct the problem or simply tell me that my work on the gun voided the warranty and quote me an estimate?

In the meantime, I re-adjusted the rear sight and shot it today in an IDPA match. Didn't do too badly. I'll shoot it again tomorrow. Hopefully, the barrel is done turning.

Thanks in advance for help and suggestions.

--j

 

[bgrafsr]

This week, I finished tuning my new (factory new from dealer) 67-5 that I am planning on using for IDPA SSR.

After finishing the internal work (polishing action parts, Miculek spring set, etc) I took it to the range for some accuracy testing. It placed reasonably nice groups with factory (UMC) ammunition, but my Rainier (158 gr .358 dia) handloads shot a 6" pattern. Back to the shop for cylinder work: ream chamber (Clymer), throat (Manson) and chamfer chamber mouths. I also cut and lapped the forcing cone to 11°.

Back to the range for another round of test firing, this time with more and varied ammo. Better groups with factory ammo. Way better groups with my Rainier reloads!

Tried some +P's as the gun is rated for +P. On the third cylinder (shots 13-18) the whole group moved 5 inches to the right!! Careful examination of the gun showed that the barrel has rotated several degrees clockwise (facing the muzzle). See pictures:

Personally, I want to simply adjust the barrel back to top center position, drill and pin it. Can anyone suggest a good gunsmith to do the work?

Failing that, I am thinking of simply loosening the barrel, applying some high temp lock tight and re-tightening it to top center position. I really don't want to go through the drama and cost of setting the barrel back one whole turn (.030"), recutting the cylinder gap and forcing cone, and shortening the extractor rod and center pin.

Or should I send it back to Smith and Wesson? Will they correct the problem or simply tell me that my work on the gun voided the warranty and quote me an estimate?

In the meantime, I re-adjusted the rear sight and shot it today in an IDPA match. Didn't do too badly. I'll shoot it again tomorrow. Hopefully, the barrel is done turning.

Thanks in advance for help and suggestions.

--j

Personally, I would take the barrel off, clean and degrease the threads, then using a prick punch, upset the front of the frame with several prick punch hits . This will upset the metal giving the barrel more torque force when tightening. You could also use some Loc-Tite to help keep the barrel from turning anymore. I have done this in the past and it works.

 

[scooter123]

I would suggest removing the barrel, cleaning it, and then applying the BLUE removeable locktite. While prick punching the frame may work it's not predictable in that those raised areas will wear down with the vibration of each fired round. I would also recomend against using the high temperature locktite because it's a bit too permanent and IMO not necessary. Think about it, when is the last time you fired enough rounds rapidly enough to get the barrel over 140 degrees? Most of us tend to set our revolvers down and let them cool off then the cylinder gets hot enough to cause burns.

Personally I'm rather conservative in my approach on something like this and do my best to avoid materials that are basically permanent. Yes, the high temperature locktite can be "broken" however it requires heat in excess of 500 degrees to do it. That means that if you find you re-installed your barrel cockeyed using the high temperature locktite you may have a rather difficult problem to fix.

 

[DCWilson]

Several thoughts.

First, welcome to active participation in the forum. I see you have been a member since 2005, but this is your first post.

I would take the position that LocTite does not belong on barrel threads, but that if you are going to use it anyway use only the low-temp blue variety.

But before you do that, think about this: Barrels can shoot themselves loose, but there is no way they can shoot themselves tighter. If your barrel is about one degree past TDC, it was tightened that way in the first place. (I won't go through the arithmetic, but one degree is about right -- not "several degrees." I calculated this from a heavy rib CM in my collection and the visible displacement in your photos.) If you shot two cylinderfuls accurately and then found the third set of six grouping five inches to the side, I can assure you that barrel did not spontaneously tighten itself in the several seconds it took you to reload.

I am a little concerned about one thing: Unless it is barrel distortion in your camera lens, it appears to me that the bearing of the grooves in your barrel is off axis by a tiny amount to the grooves in the foot of your rear sight. I am not talking about parallel but displaced, because I can see that; I mean that the grooves are not parallel, which could be the result of a bent frame or bent barrel. I don't think that could happen in the time available between reloads either (unless the gun was dropped on its muzzle at an angle), so I wonder if there was a stress fracture in the frame or barrel shank during your +P shooting. I don't want to be an alarmist, but the suddenness of the pattern displacement in a gun that was shooting correctly makes me want to look for a sudden alteration in your entire shooting system -- you, gun, ammo all working together. If you and the ammo are the same, the gun is the only thing that could have changed.

The five inch displacement in POI occurred at what distance? Five inches at 50 yards or more is less disturbing than five inches at 10-25 yards, though any sudden shift requires explanation. Since you could adjust the POI adequately with the rear sight, I gather it was at a longer distance.

Excuse a naive question, but did you have to remove the barrel to clean up the forcing cone? I don't know if that can be done with a tool operated from the muzzle end. If you did take the barrel off, then you may simply have overtightened it on reinstallation. I would probably remove it, try the punch-prick idea, and put it back on again with precise attention to TDC.

By the way, I could barely read the colored text in your post. Old guys have old eyes, and we really need the contrast between letters and field to understand what is written.

 

[john traveler]

I suspect that S&W would see your modifications on the gun and void the warranty.

Drilling and pinning the barrel in place does not completely immobilize the barrel/frame junction, not even on factory pinned models. What it does is prevent the barrel from further loosening and coming off.

The solution is to remove the barrel, degrease and clean both the barrel stub and the frame threads, and apply blue LocTite and install the barrel. Check that the barrel and front sight are aligned, of course. For more severe misclocking of the the front sight, lathe work is needed to refit the barrel shoulder, the B-B gap, and the extractor rod fit.

 

[john traveler]

DC Wilson is correct. S&W revolver barrels can shoot themselves loose, but not tighter. The right rifling twist is the key. If your front sight actually tilts to the right, it was installed too tight either at the factory, or in subsequent barrel removal/installation.

On older style Colt revolvers with left-hand rifling twist, barrels have been know to shoot tighter, but it is not common.

You might want to use the services of a qualified machinist to check your front sight alignment. Holding the frame in a milling vise on a milling machine table and running a dial indicator would be one method. Eyeball alignment is usually good enough to detect front sight tilt, but a fixture would give you a measurable value.

 

[scooter123]

DC Wilson is correct. S&W revolver barrels can shoot themselves loose, but not tighter. The right rifling twist is the key. If your front sight actually tilts to the right, it was installed too tight either at the factory, or in subsequent barrel removal/installation.

Actually John, you and DC Wilson are incorrect in your assumption. Think about it. Classic Physics states that there is an Equal and Opposite Reaction to any force vector. With a right hand twist the bullet is spinning in a clockwise direction when viewed from the firing position. As a result the barrel will actually be driven in the opposite direction when the bullet transits the barrel and that direction happens to be the same direction as when tightening the barrel.

Basically, by design the barrels on a S&W revolver should in theory shoot tighter, not looser.

 

[DCWilson]

My head is now spinning faster than a bullet with either left or right hand twist...

But I understand the equal/opposite forces argument, which leads me to ask: why would we ever hear about any barrel that begins to unthread from the frame during fire if the natural tendency is to tighten? And why wouldn't other manufacturers' products with left hand twists unthread more readily than they appear to?

I'm so confused...

 

[Magnumdood]

No...

Actually John, you and DC Wilson are incorrect in your assumption. Think about it. Classic Physics states that there is an Equal and Opposite Reaction to any force vector. With a right hand twist the bullet is spinning in a clockwise direction when viewed from the firing position. As a result the barrel will actually be driven in the opposite direction when the bullet transits the barrel and that direction happens to be the same direction as when tightening the barrel.

Basically, by design the barrels on a S&W revolver should in theory shoot tighter, not looser.

The bullet is pulling at the lands and grooves in the direction it is spinning, which is clockwise from behind the gun. Turn the gun around and the bullet is trying to drag the barrel in a counter-clockwise direction, thus, each round is applying a force that would unscrew the barrel if the barrel is already loose.

 

[john traveler]

Thank you Ralph!

That was the explanation I was going to offer with the right-hand twist rifling example. Each firing impluse tends to unscrew the barrel, and if it is not tight enough in the frame, the barrel will loosen further, resulting in the front sight leaning to the right when viewed from the rear sight.

 

[Alk8944]

This is going to pi$$ off several of you, but you are simply not thinking! Scooter123 is the only one who has been correct so far!!!!!!!!

The OP has mistakenly looked at his barrel from the FRONT and stated it turned to the right. This is akin to looking at your car from the front and stating the driver's side is the right side of the car, this is incorrect. If you understand right fron left, and which side of a gun is which you will see that his front sight, and barrel, are turned to the LEFT, this is tightening, not loosening. This is what caused his shots to move to the right on target! I am not going to get into the dynamics involved, but most of you are absolutely wrong!!!!!!!!!!!! FTF I would express this in far stronger terms.

I do not understand what the strong aversion to Loc-Tite is. In some situations it is exactly the correct approach. Why don't you think a stronger variety should be used on barrel threads? The average revolver will have the barrel removed from the frame exactly zero times, this isn't an issue. Second, and I know many of you "experts" will argue with this, but in the past S&W actually used Loc-Tite to mount barrels in Airweight revolvers. Guess what they used, Green Sleeve Mount, one of the strongest forms of Loc-Tite. I have a hard time understanding why any of you would believe what was used by the factory would be inappropriate for field repairs! I, and other gunsmiths on the forum have mentioned in the past that we have used Sleeve Mount to secure S&W barrels that are only slightly loose, but for some reason all the rest of you seem to always want to argue about this point!

Jade,

If you don't want to send the gun to S&W then by all means go the Loc-Tite route. Sleeve Mount is a catalyzed product, you will need both the resin and "Clean & Prime" to do the job. You can buy these from NAPA. It won't be cheap, but less than shipping the gun. My first recommendation is to call S&W in the morning and discuss the situation. Odds are what you have done to the gun will not be an issue, unlike many companies S&W goes to extremes to make things right instead of jumping on the smallest alteration to void a warrantee.

 

[Jade]

Thank you!

Thank you for all the responses. I will call S&W in the morning and discuss it with them. I do think the Loc-Tite solution will work. A gunsmith did it on my Model 19-5 a few years ago. I have about 6,000 rounds through that 19-5 since without a problem. Whether I go blue or green sleeve...I'll face that when the time comes.

I also appreciate the discussion of twist directions and barrel torque. My understanding of the physics is that the bullet is not "pulling the barrel" but that the force of the expanding gasses is accelerating the bullet both in terms of linear velocity and rotation. The increased rotation is achieved by forcing the bullet against the lands of the rifling. In right-hand rifling, the bullet is rotating counter-clockwise (facing the bullet), creating an equal and opposite acceleration of the barrel clockwise (when seen from the muzzle). The barrel rotation imparted by the accelerating bullet is normally absorbed by the mass of the gun and the hands of the shooter. Harsh loads in light guns actually twist the gun in the shooter's hands, as well as flipping the muzzle up.

In short, I don't think the barrel moved between the second and third cylinder of +P's. The second group strung to the right. The barrel moved from one or more bullets passing through during that second cylinder.

About the off-center grooves, that is camera artifact. I was holding the camera by hand, with my pinky finger on the end of the barrel to steady it. The lens axis is off from the barrel axis, giving the impression that the front sight is bent. It's not, although through the rear sight it has a slight, but unnerving tilt.

I'll post updates. In the meantime, I shot the gun in IDPA matches both today and yesterday without major accuracy issues, so that is some good news. Slow times. I'm still getting used to the gun.

Thanks again,

--j

 

[Magnumdood]

....
I also appreciate the discussion of twist directions and barrel torque. My understanding of the physics is that the bullet is not "pulling the barrel" but that the force of the expanding gasses is accelerating the bullet both in terms of linear velocity and rotation. The increased rotation is achieved by forcing the bullet against the lands of the rifling. In right-hand rifling, the bullet is rotating counter-clockwise (facing the bullet), creating an equal and opposite acceleration of the barrel clockwise (when seen from the muzzle)....
--j

Think of it in very simple terms:

You're trying to clean a car mat with a brush.

You set the car mat in front of you, soap it up, and shove a brush from the back (near you) to the front.

On those cleaning strokes which way is the car mat going to want to move as the brush is pushed away from you while on the mat?

The mat is going to try and follow the brush because the brush is "pulling" the mat along with it.

It's really quite simple and the "flat-earth" society is putting forth a fallacious explanation/argument.

 

[Jade]

Flat Earth !?!?

Think of it in very simple terms:

You're trying to clean a car mat with a brush.

You set the car mat in front of you, soap it up, and shove a brush from the back (near you) to the front.

On those cleaning strokes which way is the car mat going to want to move as the brush is pushed away from you while on the mat?

The mat is going to try and follow the brush because the brush is "pulling" the mat along with it.

It's really quite simple and the "flat-earth" society is putting forth a fallacious explanation/argument.

Hmmm...my lawn is flat. It's earth. Therefore the earth must be flat. Makes sense.

In terms of the topic at hand, you are partly right, Magnumdood. The expanding gasses are pushing the bullet through the barrel, away from the frame. Therefore there is a vector that wants to separate the barrel and the frame. If the rifling went straight down the barrel, instead of turning, that would be the only vector and the barrel would want to unscrew.

The right-hand rifling introduces a second rotational vector in the opposite direction. Which is vector has more force will tell you which direction the barrel will turn. In this case, without filling up several screens with math, the more forceful vector seems, empirically, to be the one tightening the barrel.

For what it's worth, I think I understand how my 67-5 got to where it is now. The presenting problem is how to get it back to where I want it.

--j

 

[Jade]

Update

I called Smith & Wesson customer service this morning. Got a person right away, and he knew what I was talking about. Two good signs. He explained that any internal work would not affect the warranty on the barrel-frame juncture. If I had removed the barrel myself, that would void the warranty. I'm waiting for the warranty call tag and this gun goes back to Smith.

Thanks for everyone's input. I'll know more in a month. Stay tuned.

--j

 

[TAROMAN]

Glad its getting worked out.
Now I know why they put those pins in there!