Cases bulging near head. .357 Magnum R92

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donhuff
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Re: Cases bulging near head. .357 Magnum R92

Post by donhuff »

Toddm,
I strongly advise againgt going to the 360DW chamber. I'm still trying to get my gun to feed the longer round "reliably". And the 100-150 fps gain in bullet speed is just not worth all that trouble.

I have lost a lot of my 360 brass to the same problem as you are having. The quest for more velocity means higher pressures, and this makes my cases bulge exactly like yours are doing. If I back off, the brass does ok, but then whats the point in that? And no, it's not because I cut the chamber out. It was already like that at the rear end of the hole, I only reamed a little out at the front of the chamber, and reamed a new longer throat section.

I think they make the chamber that way to help getting the round into and out of the chamber. A perfectly straight walled chamber would be a lot harder to deal with especially since most of us reloaders like to use oversized bullets too. SAAMI specs also show some taper in a "perfect" chamber. .0008" of taper, which really isn't very much. SAAMI also shows that all chamber mesurements can be up to plus .004" over, but no undersize allowed, understandably. And looking at your case mesurements, you appear to be right on the maximum allowed size of .3849-.385 since your largest bulge measures .384.

One thing that adds to the bulge looking so big is that rarely are new cases at the .379 size. I measured a handful of new 360s and they were all .3765". If they were at the full .379, that bulge would look a lot smaller. But again SAAMI specs say this measurement can go as much as .006 smaller than .379, so imagine what that brass would look like with the same amoult of bulge in it.
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Re: Cases bulging near head. .357 Magnum R92

Post by Ohio357MagFan »

Ok I'm a little confused now, I get the same bulging too with hot loads and it goes away when the loads are lightened. The same hot loads do not bulge one bit when fired in my revolver, not even the most hot loads. What I'm confused about is the bulging coming from the chamber not being fully supported for better feeding in the Rossi (kind of similar to the chambers in Glock barrels and how hot loads especially in the .40 caliber glocks can bulge the brass) OR is it because of that whole issue of the lever action itself being rear locking and stretching the brass with hot loads? This is the first time I'm hearing about the chambers being a lil sloppy in the Rossi
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Re: Cases bulging near head. .357 Magnum R92

Post by GasGuzzler »

I haven't had the issue but mine's old.
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Re: Cases bulging near head. .357 Magnum R92

Post by Ohio3Wheels »

In a properly constructed revolver the chambers should all be true and support the cases full length so a bulge would be unusual and alarming. Both situations in the rifle could cause cases to bulge and possibly separate. A "relieved" chamber mouth to fix a chambering problem done to extreme and the action give could combine to cause case bulges and separations. With bulges I'd recommend backing off a few tenths until they go away and not reuse the bulged cases. Case separations are no fun to potentially fatal happenings and the '92 action is not vented to keep the gas and debris away from your body parts.

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Re: Cases bulging near head. .357 Magnum R92

Post by GasGuzzler »

Revolver has cylinder to forcing cone gap that reduces effective pressure. With appropriate timing and cylinder machining the revolver doesn't allow brass to move back on the shot. I think that's what was just written above, sorry.

That being said, how much does the case move back during ignition on an R92? I get that the bolt locks from the rear but how does that cause "slack" enough to bulge brass on a gun with a non-Dremmelled mouth.....or is the Bubba-Chamber the only issue that can cause bulges?
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Re: Cases bulging near head. .357 Magnum R92

Post by dek1165 »

I recently sent my .357 back to the UK distributor and yesterday they contacted my local gun shop and informed them that it's "normal". Mine is a 20" blued octagonal barrel however I've seen several in stainless, both round and octagonal, that don't have the issue. Is it a coincidence..........

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Re: Cases bulging near head. .357 Magnum R92

Post by GasGuzzler »

I guess this is why my Purple Paper Eater doesn't bulge brass. No work to the chamber on this old girl (don't call your wife that if she's only 30).

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Re: Cases bulging near head. .357 Magnum R92

Post by Ohio3Wheels »

That is a proper looking chamber.

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Re: Cases bulging near head. .357 Magnum R92

Post by Ohio357MagFan »

GasGuzzler wrote:Revolver has cylinder to forcing cone gap that reduces effective pressure. With appropriate timing and cylinder machining the revolver doesn't allow brass to move back on the shot. I think that's what was just written above, sorry.

That being said, how much does the case move back during ignition on an R92? I get that the bolt locks from the rear but how does that cause "slack" enough to bulge brass on a gun with a non-Dremmelled mouth.....or is the Bubba-Chamber the only issue that can cause bulges?

I've always been curious about how a sealed barrel with no cylinder gap like our Rossi 92 vs a revolver with barrel/cylinder gap would effect peak PSI pressure. One thing I notice for sure by looking down the barrel with a bright light is the distance the bullet needs to travel to get to the rifling appears to be a lot longer on the revolver and my understanding is a longer leade lowers pressure
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