Circumferential Case Separation . . . .357 Magnum ?!?

[DHC]

I know this forum is more oriented toward the AR platform, but what the heck . . .

Took a few guns out for a 1/2 day at the range on Friday. Went with a couple 9mm handguns, couple of .223's and decided to take along the Browning B-92 lever action in 357 mag.

We were really enjoying the little Browning. I made a 100 yard offhand shot on a 6" plate and went to rack another round, when I noticed the spent casing looked a lot like a 9mm case as it tumbled onto the ground. Tried to rack another round and could not get the round to chamber (thankfully). After a minute or so of trying to figure what was going on, took a look at that spent case, and sure enough, it was exactly the length of a 9mm case and ragged all around the edges. Clearly the case had separated along the circumference and the remainder of the case was/is still in the chamber preventing another round to be chambered.

This was brand new Winchester brass. Had fired about 50 of the same loads and on inspection see no signs of overpressure. I am fastidious (to the point of obsessed) about my loads, so I don't think that particular round was any different than the others. In fact, the half a casing that extracted showed no primer flow. From all appearances, it looks like just a crappy case from the manufacturer.

Anyone ever had anything like this? What's the procedure for getting that half a casing out of the chamber?

[BPTactical]

The only time I have seen a case head separate cleanly like that was an out of battery fire, but it was very apparent when it occurred.
A broken case extractor but I don't have one in 357, but I do have a couple of other tricks.
Come see me.

[Great-Kazoo]

take pictures , e-m winchester, include lot number and hopefully you have a receipt, if not oh well, but it helps. They move kind of slow however you should be taken care of .

[cstone]

take pictures , e-m winchester, include lot number and hopefully you have a receipt, if not oh well, but it helps. They move kind of slow however you should be taken care of .

If it is a reload, I doubt Winchester will give him the time of day.

I am curious to know what the cause was. If you take it to BP, please let him post up his best possible explanation for the cause. I would much rather learn from your misfortune than repeat it.

I'm glad you weren't hurt and it sounds like the gun will be fine once the broken case is removed.

Be safe.

[DHC]

If it is a reload, I doubt Winchester will give him the time of day.

I am curious to know what the cause was. If you take it to BP, please let him post up his best possible explanation for the cause. I would much rather learn from your misfortune than repeat it.

I'm glad you weren't hurt and it sounds like the gun will be fine once the broken case is removed.

Be safe.

I thought I would update this thread for anyone interested.

This first photo shows the part of the case that separated and was extracted on the left, next to a regular size .357 Magnum case on the right. You can see the ragged edge where the case separated.





Here is the load date:

Case: Winchester
Primer: Winchester Small Pistol Magnum
Bullet: 142gr Montana Gold FMJTC
Powder: 19.0gr H110

Since the max chamber pressure spec for 357 Magnum has undergone changes in the past few years, there is some conflicting information on whether this load falls within spec or not. I just used QuickLoad to check once again, and the SAAMI spec (as now revised) is exceeded, but this load falls within the CIP spec for pressure.

Note in this next photo that there is no over-pressure indication in the primer or primer pocket - which is where I usually look for early indicators.



This final photo of ANOTHER case from that same batch of Winchester loads also shows signs of early case separation, though much lower on the case.




I also had a number of rounds with the same load only in Starline cases and not one of those had any problems.

The smith who extracted the case told me he could see nothing wrong with the gun, though he went ahead and polished the chamber just to be sure.

It seems the root cause is most likely some brittle brass from Winchester being loaded too hot at the upper limit of the loading spec.

IHTH

[cstone]

Thank you for the update.

I don't think I would catch that during my case inspection.

Be safe.

[Great-Kazoo]

19 grs of H110?? That's max load. Of course those cases don't look safe at all . I would suggest running 17gr, based on the hodgon data for 140 and 146 gr bullets.. The loads i did with 110 at 17grs shoot very mild out of a 16" lever. OT: i switched to Titegroup as i use 5.2 grs vs 17

[rpm]

I have a 5.56 case that did the exact same thing. I believe it was from a box of American Eagle or Federal? I'm don't recall exactly, the ammo belongs to my brother. Lake City brass:

[Madusa]

Just guessing, The case is under pressure and gripping the inside walls of the chamber while the locking plate (I don't know what the real name is) supporting the head of the case flexes just enough to stretch the case tell it breaks. I don't have a Browning 92 but if it's like a old Winchester 94 it isn't the strongest action out there. Marlin lever actions have been bragging about how much stronger they are over Winchesters for ever just for this same reason. Operating pressure on a 30-30 is 42,000 and 357 is 35,000. My book puts your loads a little hotter than 35,000 psi. Just some thought.

[DHC]

Just guessing, The case is under pressure and gripping the inside walls of the chamber while the locking plate (I don't know what the real name is) supporting the head of the case flexes just enough to stretch the case tell it breaks. I don't have a Browning 92 but if it's like a old Winchester 94 it isn't the strongest action out there. Marlin lever actions have been bragging about how much stronger they are over Winchesters for ever just for this same reason. Operating pressure on a 30-30 is 42,000 and 357 is 35,000. My book puts your loads a little hotter than 35,000 psi. Just some thought.

I've been trying to re-create my thinking that led to the 19.0gr H110 load. There were a couple of contributing factors:

* In 1992/1993 SAAMI down-rated the pressure spec for the 357 Mag to its present max of 35,000 psi. Previously, it was spec'd at 43,000 psi. Some of the loads found on the internet were developed prior to the de-rating. I was looking for loads specifically developed for lever action rifles and that is where I came across that load data.

* When I check a load in QuickLoad I sometimes see 2 entries for a given caliber, as in this case. One is based on the CIP standard and the other is based on the SAAMI standard. As it applies to 357 Magnum, the max pressure is shown as 35,000 psi per SAAMI and 43,511 per CIP. The load I used with 19.0gr of H110 is predicted to produce a pressure of 43,337 psi which exceeds the SAAMI spec but is within the CIP spec.

I read elsewhere that pressure indicators in rifle ammo are more reliable than pressure indicators in handgun ammo - that is, with handgun ammo there are often no advance indicators of high pressure until there is a failure of some sort. In my case, the case separation and then a couple of blown primers served to convince me of my mistake.

IHTH

Note to Mods - this thread may be better placed in the reloading forum as it may serve to help others avoid the kind of mistake I made.