K-Frame Forcing Cones

[ColColt]

I'll be receiving a 66-4 about the middle of next weeks but am beginning to get questions in my head about shooting 357 Mag's though it much since I've read here and there about forcing cones cracking...usually at about 6 o'clock. Not that I plan on a lot of full bore fire snorting 357's but was curious as to the credence of and number of these occurrences. I'm sure it has happened as I saw at least two pics from different people showing it. If this had been a serious problem I feel sure S&EW would have addressed it long ago but would like some comments/feedback since this is my first K-frame and don't know it's strengths/weaknesses.

I'll primarily be shooting lead SWC's for the most part so, this shouldn't be a real problem for me-just curious about the forcing cone issue.

 

[murphydog]

The lower part of the forcing cone on K frame .357s is thinner to clear the yoke as it closes. By reputation, the full 125 gr loads cause this to occur most quickly. In my opinion it is likely a matter of repeated impacts on the metal - the more force and repetitions it sees, the more likely it is to fatigue and possibly crack. Some have reported multiple thousands of full-power rounds without problems, however, so limited .357 use will probably never pose an issue for you.

 

[blue70chevelle]

S&W only suggests using 158gr rounds when shooting .357s through there k frame revolvers for just this very reason. The lesser grain rounds are too hot to withstand a steady diet of them in the k frame platform.

 

[Sebago Son]

You have more to worry about from an alien invasion from mars than if your Model 66 barrel is going to crack.

 

[ColColt]

You have more to worry about from an alien invasion from mars than if your Model 66 barrel is going to crack.

Tell that to the ones with cracked barrels.

I don't plan on many, if any, 125 gr loads of 22 gr of H110 but will probably consist of the 158-170 gr lead SWC's and the occasional 135 gr bullet. If I want a fire breathing load I have the GP100 for that...or, the 686.

 

[jakenov3]

66-4

if you use it the way it was intended that 66 will last a lifetime. use 158 gr. and keep it clean. if you need to hotrod it , get a N frame 27 or 28

 

[old bear]

If this had been a serious problem I feel sure S&EW would have addressed it long ago[/QUOTE

They did. It's called the L frame.
I use 158Gr.LSWC's in my M-19's ahead of 14.5 grains of 2400. If I get the urge to shoot anything hotter I use one of my L or N frames.

 

[C Islander]

My guess is few if anyone on this forum have ever experienced this problem. If someone has actually had this happen to a k frame that they own, I'd like to hear about it.

 

[M29since14]

Keep the gun clean. Don't forget the forcing cone area of the barrel. If you don't have a Lewis tool, get one. Limit the use of lightweight magnums. Drew may have overstated his case "just a little" , but in general, if your gun (I take it you are buying a used gun that has been fired) has not been abused before it gets to you, you are not likely to have much trouble with it - as long as it gets proper usage and care.

 

[Stu Honea]

I carry and shoot a Mod.19-2 that I've had for 41 years this year. It had quite a few of the hot 125's through it before this problem became known,but fortunately suffered no ill effects. These days I consider it a heavy duty .38,and since it's a defense gun piain and simple,I use loads like the 135+P Gold Dot SB 38's, the 158 LSWCHP,and Rem 125 gr. Golden Saber 357's for carry.
It sees some use with 158gr. magnums and 145 gr. Silvertips but those are not very often.
Some of the hot loads used in moderation are fine.The K frames are great carry pieces.

 

[ColColt]

According to the owner it's had a little less than 500 rounds and from the pics is in excellent condition with no known problems from what I was told. It belonged to a security officer and I don't image he shot all 125 gr Magnum loads when he did shoot it.

All in all, I won't be using it to fire 125 gr Magnum loads but I use cast bullets mostly but occasionally like to try the 135 gr Speer GDHP reloads since that's what I'll be using in it commercially from Speer. Even in the super strong GP100 I don't shoot full blown magnum loads often-maybe 25 or so every few months and that's usually 17 gr of 2400. Six grains of Universal with the 158 gr LSWC is more to my liking.

 

[poordevil]

I , myself do not worry about it. However I do remember reading in Handguns magazine in about 1988-ish the author of the article , Dwane Thomas(?) shot a model 13 with 3" BBL to the point of cracking. He stated that he shot it with nothing but factory 125gr mag for about 6 months or less and 3,000 rounds.

So he basically set out to shoot the gun to destruction and it took quite some time and effort. The crack in the forcing cone was very small and hardly noticeable.

My feeling is a person will go broke from shooting or ruin ones elbows before the gun will wear out.

P

 

[ColColt]

This is fairly recent. Although not a M66 as I'll be getting it's still a K-frame.

http://smith-wessonforum.com/s-w-smithing/249226-k-frame-magnum-issue-hits-me-positive-way.html

 

[Doug M.]

One would spend many times the cost of the revolver shooting enough of the hot ammo to prove or disprove that there is a problem. Figuring $30/box of 50 for 5000 rounds of hot factory ammo, if you can get hot magnum rounds any more, that's $3000 in ammo. Really hot ammo such as the small niche makers (think Buffalo Bore) is a lot more expensive, and anyone who cares for such is probably using an"N" frame. My recollection is that the NYSP had some K frames that did show the problem, but that they shot a lot, and all full power. I doubt I have the time or the tolerance in my increasingly arthritic hands to make this a valid concern for me.

Could it happen? Sure. Is it a real risk? Not for most of us. If I were inclined to shoot a lot of hot .357s, I'd use my 686 or buy an "N" frame. For those times when greater ballistic performance is needed, I have a .41 magnum, and my converted "N" frame .45ACP coming from Bowen's some day.

 

[blujax01]

I load .357 and shoot plenty of it through my M65. The bullet is the weight the gun was designed to use, the 158 grain. The load is 14.5 grains of 2400 which is close enough to "full house" for me. (BTW loading at home costs ~ $13.50/ 50 for some serious self defense ammunition.

There is no risk of cracking the forcing cone with this combination and quite frankly I see no reason to go with a shorter round, either 125 grain or 135 grain, which is the cause of the cracks. With a shorter round the bullet has to jump the gap and has been known to slam into the bottom of the cone upon entry into the barrel.

 

[M3Stuart]

Hurry Worry
Push and Shove
Looking for Molehills
To Make Mountains of

With all the things going well, why do I fret over irrelevant trifles?

 

[Sebago Son]

Not Really....

Drew may have overstated his case "just a little" ....

This is a 66-2 PD "Trade-In". I knew the copper that carried it. He was a gun guy. It had over 13,000 rounds of Federal 125 Grn. JHP Magnums through it before I took it and a bunch of other 66's in on trade.

I gave it a light fluff-and-buff, round butted it and have been shooting the hell out of it ever since. It's a favorite field gun of mine. I have no clue what the round count is now, but it wouldn't surprise me at all to find that it's close to 20,000.

I've owned and shot hundreds of 19's and 66's since the 1970's, including servicing the duty guns for a local PD and I've never personally had or seen a barrel ruined in a K-Mag from shooting hot, light magnums.

As infrequent an occurrence as cracked forcing cones are compared to the zillions of K-mags made, this is a non-issue.

You can baby it if you want to, but you don't need to. Use your 66 in good health and don't worry about it.

Drew

 

[aphelion]

The amount of metal removed from the bottom of the K-frame 357 barrels to clear the gas ring can vary quite a bit between individual revolvers. Some are out there that are very excessive in this regard. Those are the ones to avoid. I used to have a post on the forum that showed several examples that illustrated how much this can vary. Unfortunately it disappeared along with about 95% of my posts after the Great Post Purge a couple of years ago. I don't have the pictures anymore or I'd put them up again. However, you can compare the picture from the thread linked to above with the one of one of my 19's. Quite a difference.

My 19 -

 

[ColColt]

Wow-that is a big difference. There shouldn't be that much but maybe his was during the Bangor Punta days...who knows.

 

[nipster]

When the gas ring was moved from the yoke to the cylinder in the 13-2 and 19-4 (65-2, 66-1), I think it may have necessitated that change