A Question for the Revolver experts

[PinnedAndRecessed]

I just took delivery on a Model 19-3 Smith and Wesson. The gun looks almost unfired except some shallow cutting on the underside of the top strap just in front of the barrel.

A Smith and Wesson gun collector told me he talked to Smith and Wesson about that phenomenon. He asked Smith what happens. Smith told him that the flame only cuts so far and then it stops. I guess it must get heat treated or something.

I've heard of that happening to Smiths. I heard it was a problem with the K frames, but this collector says it happens to all revolvers.

Any comment from the experts?

 

[Maddock]

I’m hardly an expert, but I’ve seen it in most magnum revolvers that have been shot more than a few rounds. It seems to be accelerated by use of light bullet, high-speed loads. K frames seem to be the most affected. I can say I’ve never seen a revolver that flame-cut the top strap to the point that it was unusable. Forcing cones shot out – lots, but no top straps.

 

[Jim March]

Yeah, that's about the size of it. As long as no more than 10% of the total topstrap cross-section is gone, you're good. (That's a rule of thumb.)

Monitor it.

Supposedly the hotter grades of 125 ammo will cause more erosion than the 158s. 158s (even magnums) will be less stressful on that gun than full-house 125s. In my opinion, as long as you have a 3" or esp. 4" barrel 357Mag gun, the Speer Gold Dot 158s loaded to about 1,250 by either Speer, Georgia Arms, Proload or Black Hills make a lot of sense as a defense load and aren't a bad choice for lower-48 general woods carry. Most reports show they're accurate, controllable, expand well and don't beat a classic like your 19 to death.

 

[J.M.]

Yup, like you heard, it only goes so far and then stops.
Think of it as a vent path for hot gasses to escape...once there is enough of a path for the gasses to escape through, it won't erode any farther.

BTW - it is my experience that ball powders will remove material a bit faster, but not any farther. - JM.

 

[Standing Wolf]

I've seen the same thing happen to some—not all, but some—.22 long rifle revolvers.

 

[PinnedAndRecessed]

MADDOCK says, "Forcing cones shot out..........."

What are the indicators of this? Does it shoot poorly or can you see it? If it is visible, what does it look like?

 

[Old Fuff]

P&R:

The model 19-3 will outlive you and still be in good shape if you shoot lead (not jacketed) bullets for practice, training and fun, and leave the jacketed hollow points for self defense. Old time revolver shooters (including this one) have always done this, and none of my model 19's show any sign of gas cutting - either on the bottom of the top strap or the forcing cone.

Gas cutting in either place leave the metal surface looking like it was sandblasted with fine gravel. You'll know it if (when) you see it.

 

[PinnedAndRecessed]

Fuff, I shoot handloads. My standard load for the 357 is currently 8.0 grains Unique for about 1000 fps (I'm guessing). I use copper plated bullets, 125 grain flat point. Do you think forcing cone erosion would still be a problem with such an anemic load?

But, now that you mention it, I might go back to shooting lead bullets. I had given them up just because I shoot so little.

E.g., my Clark modified 1911? I shoot it, on average, of 74 rounds a year.

 

[Old Fuff]

The erosion in question is caused by flame-cutting, because of the burning rate and temperature of some gunpowder’s combined with jacketed bullets where the base doesn’t upset and seal the bore. The problem seems to occur most often when jacketed bullets weighing 125 grains or less are combined with a fast-burning powder at maximum pressures. This combination earned a well-deserved reputation for ending fights after one solid hit, and as a consequence was very popular within law enforcement circles.

But on the negative side these loads were sometimes hard on the gun. Law enforcement’s answer was to use the hot stuff; often both for training, practice and carry, and then replace the revolvers when the effects showed up. In other words, you’re tax dollars at work.

Your copper-plated bullets still have soft bases. Therefore if they are properly sized to match the chamber throats and bore you shouldn’t have any problems. However you might slightly reduce the load for strictly fun and play. It probably won’t make any difference to the gun, but you might see an increase in accuracy.

One other thing. S&W revolvers have a slow twist of 18.5 inches. This works best with 158 grain or so bullets. A faster twist of 16 or even 14 inches is usually but not always better for light bullets. You won't see any meaningful difference except at longer ranges - say 50 yards and out further.

Experimenting is half of the fun ...

 

[scottauld]

here is the skinny on the Model 19, includes important info about NOT shooting 125 grain ammo in those 1960s and 1970s guns:

http://freepatriot.com/model19.php

Stick with 158 grain .357 ammo on Model 19s. And shoot a lot of .38 Special, and a little bit of that .357.

If you keep your ratio of Specials to Magnums about 9:1, or one Magnum for every nine Specials, you'll be OK. The gun, while tough, won't take a steady diet of Magnum ammo. In particular the 125gr stuff is particularly harsh on old K frames. Only shoot 158 grain .357 ammo in this gun!!! That's straight from Smith &Wesson's mouth.

The gun was designed when the only magnum load available was the 158gr load. The 125gr load that appeared in the '70s was hotter than the 158gr load.

Modern ammo is loaded to roughly:
158gr @ 1250 fps 125gr @1450 fps

Older ammo was hotter: imagine 158grains at 1450 fps!!! Modern ammo is downloaded for liability reasons.

The lighter bullet causes a few things to happen.

1: It accelerates faster in the cylinder, striking the forcing cone MUCH harder than the 158gr bullet. Look at your forcing cone, you'll notice it's cut-out at the 6 o'clock position to allow the ejector rod to clear. As the gun recoils back, the bullet strikes the forcing cone at this 6 o'clock position and causes erosion and cracking over time. Your accuracy will go to hell and you need a new barrel.
2: the shorter 125gr bullet leaves the case before a 158gr bullet, casusing more unburned powder to fly forward and combust in the throat and barrel. This causes flamecutting on the topstrap and peening of the forcing cone. Again, very bad.
3: The recoil impulse of the 125gr loads are much sharper and severe than a comparable 158gr load, so it batters the gun HARD.
4: To be honest, the 125gr load is the most common out there, but it is not the best load. It is light and fast and while it expands violently, it tends to underpenetrate. The 158gr expands and has enough momentum to smash through and hit vitals.

If you want to shoot lots of 125gr loads, get an L-frame or even better, an N-frame. Smith & Wesson started seeing lots of K-frame magnums in for warranty work in the '70s due to shooting 125gr ammo and issued an advisory to not do it.

Cheers,
Scott

 

[Maddock]

PinnedAndRecessed - MADDOCK says, "Forcing cones shot out..........."

What are the indicators of this? Does it shoot poorly or can you see it? If it is visible, what does it look like?

Old Fuff - Gas cutting in either place leave the metal surface looking like it was sandblasted with fine gravel. You'll know it if (when) you see it.

Old Fuff's description is spot on. And if it happens, you WILL notice it.