357 mag case separation

Never seen that

I have loaded .38 and .357 for Rossi 92 and revolver. I have reloaded cases many many times. Worse I get is a small split in the case and toss it. Never had a full separation. However, I only load mild loads all subsonic.

Was there a cannelure on the case?

Wow never saw one of those. All mine split lenghtwise

Walkalong said:

Have the headspace checked.

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+1.

Reduce the powder charge . Had a Marlin 44 mag rifle do that. The lines on the brass show its sticking to the chamber, instead of sliding back. Sticking lets the case stretch and separate.

ljnowell said:

Was there a cannelure on the case?

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This - was there one??

Or bad batch of brass?

I've seen signs of a case head separation in my 16" rossi 92.

Brass was starline that had two previous firings. A mild(15.7gr) charge of W296, 18.5gr lilgun and the last reload was 19.5gr lilgun. All with a 164gr PCLSWC. Yes, I worked up from 18.0 to 19.5gr .1gr at a time. There isn't really any lilgun lead data out there so I started with 158gr xtp data, worked through that and beyond max. Lead bullets wont create as much pressure so I wasn't afraid to venture past max. I dont Think I chrono'd anything but the 18.4gr load that I settled on. It cooks along at 2,000fps on the dot.

In the picture below, you can see a fine line going about halfway around the case. No more of those heavy loads!

Look at that.... It split right along those lines in the brass. Looks like some sort of abrasion on the brass right there. Also notice there is a small split on that broken case where the crimp is.

1466 fps with a 158 grainer has some mustard on it, no? Even in a rifle?

AA#5 from their published data...
158 HDY XTP 8.6 1,097 9.7 1,256 33,150 1.590

Looks like the problem is a combination of a rough chamber and excess headspace allowing the front of the cartridge to grab in the chamber instead of sliding. The excess headspace gives it room to do so. Is there possibly a ring in the chamber from 38 specials? I bought a Rossi from a SASS shooter who had fed it a steady diet of Specials. I gave the chamber a good polishing before shooting any 357's through it.

243winxb has it.

You might want to go with Walkalong's too.

The theories on a rough chamber, too high pressure and excess head space have been mentioned. An additional cause could be a sloppy chamber. Any time you resize brass it stretches even in a straight walled case. The more it has to be resized, the more it stretches even in a straight walled case. The brass is thicker at the head so it's not going that way but rather toward the mouth of the case.

The only time I've had a head separation in a straight walled case was with full house 460 S&W Magnum loads in a T/C Encore.

Walkalong said:

Have the headspace checked.

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.357 lever guns, because of the way they lock up at the rear of the bolt and produce bolt movement when fired, are notorious for stretching brass when shot at true .357 magnum velocities/pressures. This is why reloading manuals(Speer for example) state to use only virgin or once fired brass for upper level loads in .357 lever guns. Case separation from shooting brass loaded to max several times in a .357 lever, can be expected.

Might be time for new brass.

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Given the cracks on the case necks, i'd tend to agree.

Ohh lord. Thats starline brass. I have around 3k brass from starline, mostly 9mm and 357s, and I can specifically say I have never seen that kind of "separation" on starline. That is by no means a headspace issue. No way, no how.

Reefinmike said:

I've seen signs of a case head separation in my 16" rossi 92.

In the picture below, you can see a fine line going about halfway around the case. No more of those heavy loads!

Click to expand...

You can also see the stretch marks in the right side of the picture. Another item to look for when inspecting brass.