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Old 11-07-2012, 03:37 PM
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Default A Simple M&P/Model 10 question

When a barrel cracks on a K-frame .357, it's usually at the bottom, where the barrel throat/forcing cone is machined flat, so the cylinder can close.

My only K-frame just now is a M-66-3, which I love. Would one of you guys who has a .38 like a Model 10, 14, 15, etc. please swing out the cylinder and see if the barrel is flat and thinner there on the .38's, too? I see no reason wny it wouldn't be, as the design is the same, save for different steel alloys and heat treatment on the .357's.

Don't know why, but I thought of that last night and the issue has been bugging me.

Thanks.

OH: about those cracking K-frame .357 barrels...I saw yesterday on one of the Ruger forums a photo of a GP-100 that had a cracked barrel throat, just to the right of where the flat is on K-Mags. The entire rear of the barrel was rough and eroded. The owner had been shooting 125 grain bullets with a hefty charge of powder in reloads and I think, a lot of factory 125 grain .357's. It is often said that the GP-100 is built like a tank, but this poor gun looked like it'd been hit with an anti-tank gun! Stay away from light bullets and hot powder charges in your .357!

Last edited by Texas Star; 11-07-2012 at 03:46 PM.
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Old 11-07-2012, 03:45 PM
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Yes, I just looked & my 64-6 has the flat on the bottom of the forcing cone.
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Old 11-07-2012, 03:58 PM
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Quote:
Originally Posted by Texas Star View Post
OH: about those cracking K-frame .357 barrels...I saw yesterday on one of the Ruger forums a photo of a GP-100 that had a cracked barrel throat, just to the right of where the flat is on K-Mags. The entire rear of the barrel was rough and eroded. The owner had been shooting 125 grain bullets with a hefty charge of powder in reloads and I think, a lot of factory 125 grain .357's. It is often said that the GP-100 is built like a tank, but this poor gun looked like it'd been hit with an anti-tank gun! Stay away from light bullets and hot powder charges in your .357!
When I sent my S&W 581 back to the factory for the recall modification, I was advised that my 581 was showing signs of erosion in the forcing cone. It didn't have any cracks but the factory said it would be a good idea to hone the forcing cone and reset barrel/cylinder gap. I had them do it. I don't fire those full house magnum rounds so the previous owner must have. You give good advice: just because we can shoot the hot stuff doesn't always make it a good idea regardless of the gun.
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Old 11-07-2012, 04:04 PM
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The only K frames without the flat are those with a round barrel inside a sleeve that is keyed into the frame to prevent the sleeve rotating. These are the so called two piece barrels. Their barrel can be screwed in without consideration of aligning it right side up. Their breach end is all as thin as the thinnest spot in a normal K frame barrel's flat. Incidentally, I have yet to hear a rumor of one cracking.
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Old 11-07-2012, 04:10 PM
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Originally Posted by Duke426 View Post
When I sent my S&W 581 back to the factory for the recall modification, I was advised that my 581 was showing signs of erosion in the forcing cone. It didn't have any cracks but the factory said it would be a good idea to hone the forcing cone and reset barrel/cylinder gap. I had them do it. I don't fire those full house magnum rounds so the previous owner must have. You give good advice: just because we can shoot the hot stuff doesn't always make it a good idea regardless of the gun.
I think it was Napoleon who said that you can't make an omelet without breaking eggs. (So much for how he felt about his troops' lives...)

I haven't felt the need to make any .357 omelets that couldn't use 140 grain or heavier eggs. The destruction wrought by the 145 grain Silvertip loads makes me wonder why I'd need a lighter bullet.

One of our members who's retired from a Dallas suburban dept. posted awhile back that Dallas PD found the 145 Silvertip VERY effective on humans. It will probably knock the daylights out of a coyote, too, even a wolf. On larger animals, I'd use heaver bullets or a heavier caliber altogether. But the 140-145's are probably lethal on cougars, although I'd carry 158 grain Hydra-Shoks, in case I had to take a frontal chest shot or break a shoulder.

Last edited by Texas Star; 11-07-2012 at 04:15 PM.
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Old 11-07-2012, 06:18 PM
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Refresh my memory please... I do remember the .357 K frames having some issues with forcing cone erosion and cracking, but what bullet weights are known to be, or at least alleged to be, safe?
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Old 11-07-2012, 06:36 PM
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Refresh my memory please... I do remember the .357 K frames having some issues with forcing cone erosion and cracking, but what bullet weights are known to be, or at least alleged to be, safe?
Contrary to the "well established internet fact" that 125 grain loads wear forcing cones faster, IMO, the answer to your question is no bullet weights are safe. However, I watched a gentleman wear out two model 19 forcing cones and it took so many rounds that I am not the least bit worried about wearing out my K frame .357s. Both of his forcing cones eroded away so bad before cracking that you couldn't help seeing that they were thinner at a glance. He fired almost exclusively 158 grain jacketed bullets with full loads of 296 or H110. IMO again, if you don't even shoot enough magnums to erode the tool marks out of your forcing cone, you have nothing to worry about. Incidentally, S&W replaced both of my friend's barrels for free, which I've read they no longer have the barrels to do.
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Old 11-07-2012, 06:51 PM
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Imaposer,

Supposedly, and backed by enough comments and evidence here in the past that I give it credence...shooting full-house .357 loads with bullets at, and below, 125 grains, causes some forcing cones to crack in the K Frame .357 revolvers.

Supposedly caused by hot, erosive powders such as H110/W231, or leaded up/fouled forcing cones, and the fact (not sure if proven) that the shorter 125 grain or less bullets allow more hot gases to effect the forcing cone.

I load my K Frame .357s with 158 grain lead bullets at top velocities and try to avoid H110/W231 (although I like those powders) but if the most accurate load is H110/W231, I will use it.

As k22fan posted, it might take a lot of rounds to do the damage. As Texas Star reports 140/145 grain loads are effective enough and maybe better penetration-wise than the lighter bullets.

I too like the 140/145 grain bullets because if one really wants expansion, he/she might get it more often in the 140/145 grain bullets versus the 158 grainers.

I have also heard that Colt "D" frame revolvers (Diamondback, Police Positive, Detective Special) may also crack forcing cones. Probably from excessive lead buildup.

One person did come onto this forum a while back and he posted a K38/M14 with a cracked forcing cone from standard .38 Specials. He had bought it used and it is possible the previous user caused the problem from failing to clean the forcing cone.

I have since begun to religously clean the forcing cones on ALL of my revolvers, regardless of caliber, after a shooting session.
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Old 11-07-2012, 07:31 PM
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Thanks for the info, guys. I was thinking that I remembered it being the full house loads in 125gr and below that was the usual suspect but I wasn't sure if I remembered the stories correctly since It's been a number of years since I read about the subject in some gun rags.

I currently only have 1 K frame, a 3" model 66 that I dearly love. But, I am also always on the lookout for the right model 64/65 or 10/13. Something about the K frames that just seem to fit me well. I've never shot too many hot .357's in it though, for fear of causing damage. Well, that and the fact that I just don't see the need just for fun shooting. I tend to shoot mainly my own light, powder puff loads of 148gr HBWC's over various fast burning powders like Bullseye or Universal Clays. But, I do venture outside that on occasion so I just wanted to refresh my memory as to the conventional wisdom regarding this issue. Doesn't sound like I have to be unduly concerned though.

I will keep an eye on the lead buildup though, since I generally do shoot cast bullets in it.
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