125 grain 357 Mags in a K Frame – what’s the catch?

[OTTD]

Hi everybody,

It's been said, that the forcing cone of a K Frame revolver will suffer/could crack, when .357 Mag with a 125gr. projectile is used. Is the 125gr projectile too fast? Is it pressure? What's the technical reason behind this statement?

Thanks for your help, Daniel

 

[Ga Johnny]

As I understand it there's still alot of powder burning going on when the bullet jumps the gap between the cylinder and forcing cone, more than is the case with heavier bullets. I guess the theory is the still burning powder causes increased stress on the forcing cone. May be BS I don't know but that's the story I've always heard.

 

[David LaPell]

There was a sort of scientific study done, I believe you can find it on GunBlast, where they took a Model 19 and shot one until the forcing cone cracked. Apparently according to what was written there was that the K .357's were designed to fire just the 158 grain bullets. If I remember right it was the fact that gasses were actually getting around the smaller 125 grain bullets and causing severe pressure buildups. After having had a couple of K frame .357's, I can honestly say I much prefer the N frames, they fit my hands better and I never worry about what I can shoot through them.

 

[m1gunner]

Too much energy in that round for the cut away forcing cone. No problem in a N frame.

 

[ArchAngelCD]

The explanations so far have covered the problem. I highly suggest you not fire a steady diet of 125gr bullets from your K frame. Practice with 158gr bullets and carry 125gr bullets if you must but it's my opinion a 158gr bullet will do a good job of stopping anything it hits.

If you really want to shoot 125gr ammo you might want to buy a L frame S&W since that's what it was designed to shoot.

 

[vytoland]

previous posts on the 125gr ............k frame subject

http://smith-wessonforum.com/s-w-re...106312-smith-wessons-position-125g-357-a.html

http://smith-wessonforum.com/s-w-revolvers-1980-present/96895-k-models-125g-vs-158g-bullets.html

 

[kenpofan]

This just never gets old, just retold..

Keep your K-Frame clean and shoot factory loads and you will be fine.
Hot !! 70's loads did cause some damage to 19's (pre 4) k-frames.
But did so with other weapons as well.
When Smith and Wesson prints a recall for those weapons, I'll change my mind.

Hint..If this was a catastrophic issue you can bet the farm they would lawyer up and recall each and every K-Frame they could get their hands on.

 

[Steve C]

The forcing cone on the .357 mag K frames are machined flat on the bottom to allow the cylinder to close in the smaller frame pistol. This makes the bottom portion of the forcing cone thinner and this is where it will crack. N and L frame pistols and Colt Pistols don't have this thinner portion of the forcing cone so it is not an issue with those pistols.

Here is the link to an article on Gunblast published in 2006 that's good reading regarding the Model 19 and magnum loads causing the forcing cone to fracture. Use of Magnum Loads in S&W Model 19 and Other K-Frame Magnums

 

[OTTD]

I'm a center fire pistol paper hole puncher. My experience with revolvers and it's ammunition is limited.
There's a couple of Webley, Enfield and S&W in .38S&W or .455 Eleys in my collection. Beautiful pieces, nice to shoot, but they are not famous for a superlative ballistic performance. My new to me 2 ½" Mod 19-3 is the hottest of it's kind.
I'm not concerned about the 125 grain loads at all. I can live without out it, but I'm interested in the story behind the story.
It's obviously corrosion problem related to hot gasses passing by a too short projectile before the projectile enters the cone/barrel. That makes sense to me.
Thank you all for your kind help, the additional information and links.
Regards, Daniel

 

[GPerry]

For years the accepted practice in law enforcement was to train with .38's and carry .357's. The K-frame handled this just fine. Then, in the 70's, after the Newhall incident (calling for more realistic officer survival training) and some adverse civil litigation (suits against departments that trained with one thing but carried something much different), law enforcement firearms training emphasized training with the same magnum ammo carried on the street. The 125-grain load was state-of-the art. It was also loaded hotter than the hinges of hell. Putting a high volume of that hot load through a K frame in a short period of time was hard on the forcing cone.

Massad Ayoob, who has extensively documented the issue over the years, mentions it indirectly here:

YouTube - gpepin1's Channel

The attached photo from the cover of his book StressFire graphically illustrates him firing the 125-grain load. Mas also chronicled the hot round's effect on the Model 66's gas ring, which expanded and tied up the cylinder, jamming the gun. Redesigns helped somewhat, but eventually S&W went to the L-frame, which I believe is what Mas is shooting in the photo.