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Old 06-18-2011, 05:00 PM
sbcman sbcman is offline
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Default M&P340 Locked-Up! Help Me!

Need some ideas here as to what might have gone wrong with M&P 340 today. I put one cylinder down range and then loaded another cylinder. One shot fired and then the next shot I thought misfired on me. It wasn't a misfire. I thought the infernal lock might have set on me, but it was unlocked. The cylinder is froze for some reason and the trigger/hammer won't come back.

I had this happen once on a Ruger LCR and it was the return spring that snapped on me. But when I pulled the sideplate off the M&P, everything looks right.

Any ideas as to what I could look into to find the problem?

Thanks!
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Old 06-18-2011, 05:04 PM
sbcman sbcman is offline
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Forgot to mention that I was shooting starting load 38 reloads of power pistol, so bullet jump isn't a problem here.
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Old 06-18-2011, 05:17 PM
KAC KAC is offline
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sbcman,

Can you see light through the barrel/cylinder gap? If not you probably have a bullet stuck between the chamber and the barrel. You will need to drive the bullet back into the chamber with a range rod before you can open the cylinder.

KAC
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Old 06-18-2011, 05:28 PM
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Look for a high primer.
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Old 06-18-2011, 06:47 PM
Wee Hooker Wee Hooker is offline
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Two of the likely causes are already covered. ANother is bullet jump caused by recoil. Start with the range rod (use a wooden dowl if you don't have one.) then inspect for the other causes. Good news is that it's an easy fix.
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Old 06-18-2011, 07:35 PM
sbcman sbcman is offline
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Thanks for all the suggestions guys, here's a little more detail.

The cylinder won't just not turn, it will only fall out half-way. Also, the cylinder gap is completely closed (I did push the bullet back all the way just to be sure). The release side also has some odd back play that's not usual. I'll look into it further and update. Any new ideas, keep'em coming.

Thanks.
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Old 06-18-2011, 10:56 PM
sbcman sbcman is offline
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Swooo! OK, I was wrong and you guys were right. I did have a bullet pull out BIG TIME. Long story short, I have spent the evening learning more about j-frames than I ever thought I would. At least now I know I can tear one down (as in, to the frame) and put it back together.

I had to do unmentionable things to my little hammerless, but it's all good now.

Thanks to everyone!
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Old 06-19-2011, 06:00 PM
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One more thing, use only jacketed ammo in those titanium models.
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Old 06-21-2011, 04:25 PM
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Quote:
Originally Posted by Old cop View Post
One more thing, use only jacketed ammo in those titanium models.
The M&P 340 doesn't use a titanium cylinder like the PD models. It uses a blackened (PVD) stainless steel cylinder. It occupies a weight range between the Ti/Sc guns and the standard aluminum alloy +P rated J's (642/442). It does have the alloy sleeved barrel and an alloy yoke, where the 642/442 use a solid steel barrel and a steel yoke, though, which is what helps reduce the weight of the M&P models.

The point is well taken, though.

Even though my own M&P 340 weighs in at 14.3 oz (I added standard rubber grips instead of the bantam) instead of 15 oz like my 642-1's, I still check each brand of ammunition I use in it to make sure I don't see any indication of bullet pull. I'll even occasionally check random rounds from new boxes of brands I've previously checked, just in case some production tolerance issue or change may have occurred and it might be noticed with some test shots.

As a matter of fact, it's not a bad idea to check for bullet pull in any J, I'd think, even the all-steel models.

One of the other instructors was running a class and qual range a while back where one of the shooters was using an older blued M36 (all-steel) J-frame with some imported standard pressure LRN ammunition. The shooter experienced repeated instances of bullet pull, with several bullets jumping their crimps and sticking out the front of the cylinder charge holes far enough to stop the cylinder from turning (fortunately before they came up under the hammer).

I remember talking about bullet pull with someone from the factory once, and he mentioned that they had seen some increased instances of what seemed to be "looser crimps" with one well known brand recently (at that time). When I asked a load of another brand, he said they hadn't tested any of that brand & load, to his knowledge, at that time, but that they were buying and testing a lot of the major brands of ammunition at different times and I could always call back and ask later.

The way things can sometimes change in production runs, or when a company may make a change in a component (bullet or brass case), I feel better occasionally checking random rounds pulled from boxes to look for any signs of bullet pull (or other problems), as described in the revolver safety manual.
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Last edited by Fastbolt; 06-21-2011 at 04:30 PM.
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  #10  
Old 06-22-2011, 12:47 AM
sbcman sbcman is offline
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OK, a little update here.

It bothered me greatly that the bullet "pulled" because I always put an ultra tight crimp on them. I checked out my reloading gear and all was fine. I then happened to look at the cases and rounds that came out of the jammed cylinder and that's when it hit me....

Squib.

The primer was set off on the round that jammed the gun but didn't ignite the powder. I guess the primer had enough "oomph" to push the bullet almost all the way out of the case. This explains why I thought the bullet really pulled out because there was only about .005 in the case.

In a way, I am very thankful to God that the cylinder jammed up. Just a bit more and I could have put another round through with a barrel obstruction. Of course, I'd like to think that I would have noticed a round didn't fire (it's pretty obvious on the 340, but I might not have.
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Old 06-22-2011, 08:48 AM
KAC KAC is offline
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Just curious. what was the position of the round that bound up the action? Was it in line with the barrel, or off to the side? Not sure if this is clear.

KAC
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Old 06-22-2011, 09:36 AM
sbcman sbcman is offline
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The round that jammed everything up was the round being fired; in-line with the barrel. The bullet was stuck in the barrel with just a hair left in the case. I wouldn't have noticed it after all was said and done except I saw that the primer had been struck.
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Old 06-22-2011, 10:23 AM
KAC KAC is offline
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"Of course, I'd like to think that I would have noticed a round didn't fire (it's pretty obvious on the 340, but I might not have."

I find that when practicing, and the hammer falls on a round without the expected noise and/or recoil, it is good practice to check for a squib or bullet in the barrel. What I am hearing from you is you were not aware the round did not go off. Or, am I not reading the postings right? Glad it all worked out for you.

KAC
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Old 06-22-2011, 11:16 AM
sbcman sbcman is offline
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Correct- or better said, I didn't hear the primer go off (I wear some pretty intense hearing protection). I thought it was a misfire. When I went to check it is when I found I couldn't open the cylinder.

I agree with you, that is a good practice. But I have seen guys continue to fire after a failure. Particularly, a guy was shooting 9mm and had a squib but didn't know it. The case jammed on him, he cleared it and proceeded to rack another round and fire. I would hope I always have presence of mind to check, just saying I could have made a mistake. Good thing is that events like mine help to enforce good habits- it'll be on my mind from now on.
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340, 442, 642, crimp, hammerless, lock, m36, primer, ruger, sideplate, sig arms, titanium

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