Magtech 38 Special - bullet pull/jumped crimp??

307-Niner

307-Niner

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Decided to get out & practice some more today. Here's the not-so-pretty results...



Gun locked up after 3 shots. This is my M&P 340 .357 Magnum. The bullet on the far left of the pic is brand new out of the box to show normal seating of the bullet. The other five were in the cylinder when it locked up. Here's a closer pic.



This was at the tail end of a new box of 50 that I recently purchased from my LGS. The gun never locked up before with this ammo, but now I wonder if the rest of the box was also jumping crimp. The longer .357 mag cylinder would have masked the problem.
 
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So my next question is this:

Who makes ammo with a strong enough crimp to prevent this?
 
That should not happen with any ammo. I would guess that the crimp was not done correctly at Magtech. They really should not need much crimp for 38 Special but with the cannelure it should have been done.
 
Thanks for posting this. I'll keep Magtech out of my M&P 340. I haven't experienced any crimp jump with the ammo I have used so far.
 
I reload now, but in the past I've shot a lot of Magtech .38 Special and never had that problem. The first round in your photo looks like it has a decent crimp.

I have loaded hot .38 Special loads where the brass I was using was either too weak or too thin, and had a few break the crimp.

I would contact the manufacturer.
 
Golphin said:
How hot did these feel when you were shooting them? Do the empty cases and primers look normal on the ones that you did shoot?
Click to expand...

Comparing them to the .357 mag Remington 158 gr JSP's (full house loads), they are pretty tame. My wife can shoot the 38's with my M&P 340 just fine, but doesn't like the .357 Remington at all.

The empty casings and primers look completely normal to me.
 
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Jinglebob said:
I reload now, but in the past I've shot a lot of Magtech .38 Special and never had that problem. The first round in your photo looks like it has a decent crimp.
Click to expand...

The second round in my pic has also jumped, just not very far.

I'm guessing that there were probably several bullets from this box of 50 that jumped crimp. But the gun didn't lock up because of the longer cylinder chambered for .357 mag.

I have read suggestions from other threads where members recommend measuring OAL on all ammo you shoot in order to test your ammo for jumped crimp. Guess I'm going to take up that practice now.
 
307-Niner said:
So my next question is this:

Who makes ammo with a strong enough crimp to prevent this?
Click to expand...

I haven't tried a lot of different loads in it yet. But, I didn't have any issues with Winchester White box 130 gr. 38 SPL, WWB 125 gr. 357 Magnum, Remington Golden Saber 125 gr. 38+P and, 357 Magnum.

I've also shot CCI/Blazer Aluminum 125 gr. 38 SPL +P and some Federal American Eagle 130 38 SPL. As well as, the Speer Gold Dot 135 gr. 38 SPL+P. "short barrel."

Unfortunately, there aren't a lot of factory 357 Magnum loads "in stock" in the shops around here. GM may have some but, I try to avoid them. But, I really would like to find more 125 gr. Magnum loads to test that aren't a $1+ a round.
 
So what exactly is happening here? I'm assuming that jumping crimp means the casing was not crimped tight enough around the bullet? How does this affect the firing of the gun? Honest questions here as I'm fairly new to shooting. I just shot 100 rounds of this exact ammo yesterday out of my 681 without problems.
 
Defective ammo.
I shoot a lot of that load from Magtech, never had that problem.
I'd contact Magtech.
FWIW, that load averages 802fps from my 4" mod 15.
 
There are no hard, fast rules anymore re crimp jump. As the OP points out, even .38s can "c-j" and we are led to believe it should happen only with .357 loads not properly crimped. I'm not surprised it happened in a "flyweight" and not in a 686.

I just experienced c-j in a 642 with Fed 158gr LHP +P. Not enough to tie up the gun, but I checked the 5th round 2x and the bullet had moved forward in the case. I must next test a 4" 64HB and a steel frame 649 to see if the weight of the heavier frames prevents c-j. One must today check one's ammo carefully if used in a SD/carry piece.

YMMV. The Federal 158 LHP loads you have may not have this problem. As I said, no hard, fast rules in this area, although the smaller, lighter guns seem to be more susceptible. Testing / experimenting is paramount.

Kaaskop49
Shield #5103
 
If you shoot enough some stuff eventually happens. I had this very same thing happen while shooting my Colt Cobra, don't recall the brand anymore. I've also had hard primers that needed a double strike to ignite. All this was range ammo so I don't worry about it much.
 
By the look of the picture, there's a hefty roll crimp on those rounds, especially for .38s and especially for factory. Many of my full house .357 mag loads are not crimped that heavy. I suspect that maybe the brass was annealed too much and became too soft, thus the crimp is not holding.
 
1320ft said:
So what exactly is happening here? I'm assuming that jumping crimp means the casing was not crimped tight enough around the bullet? How does this affect the firing of the gun? Honest questions here as I'm fairly new to shooting. I just shot 100 rounds of this exact ammo yesterday out of my 681 without problems.
Click to expand...

If the round isn't made properly, the recoil causes the bullet to pull out of the case(jumping crimp). If they only pull out a little and then stop, you may fire all 5 or 6 shots and never know it happened. If the bullet pulls out enough, it sticks it's nose out of the front of the cylinder and prevents the cylinder from turning. When the bullet contacts the frame as the cylinder tries to rotate, you get something that looks like the 3rd round in the photo.
BTW, this is usually seen as an ammunition problem, not a revolver problem.
 
I have shot several types of 357 out of my M&P340 and thay never happend. Some Blaser 357 158 plinking ammo. Speer Gold Dots 135gr low flash low recoil. Speer Gold Dots 135gr full power. Some old Federal 125gr HPs. No issues.

Never shot magtech through it.
 
HarrishMasher said:
I have shot several types of 357 out of my M&P340 and thay never happend. Some Blaser 357 158 plinking ammo. Speer Gold Dots 135gr low flash low recoil. Speer Gold Dots 135gr full power. Some old Federal 125gr HPs. No issues.

Never shot magtech through it.
Click to expand...

Respectfully, you've discovered several types of combat ammo that work in your gun without c-j. Don't drive yourself batty trying to find other loads that will c-j! That's not the purpose of your 340, which is to protect you and yours. Forget Magtech!

So Blazer .357 works in your 340 but not in my 360. See what I mean about testing?

Kaaskop49
Shield #5103
 
I have used several different loadings from MagTech, but never in a 340, used in a 442 and a 67, no problems.

I did have that same problem with Sellier & Belloit ammo in the 67, upon examination it looked like most of the box was not crimped at all, you could pull the bullets out with your fingers.
 
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oldgranddad said:
If the round isn't made properly, the recoil causes the bullet to pull out of the case(jumping crimp). If they only pull out a little and then stop, you may fire all 5 or 6 shots and never know it happened. If the bullet pulls out enough, it sticks it's nose out of the front of the cylinder and prevents the cylinder from turning. When the bullet contacts the frame as the cylinder tries to rotate, you get something that looks like the 3rd round in the photo.
BTW, this is usually seen as an ammunition problem, not a revolver problem.
Click to expand...

Thanks for clearly answering my questions oldgranddad, I appreciate it! I understand now and know what to look for.
 
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