Ring around case head

[Ohio357MagFan]

I attached some pictures, I hope they come out ok. I took some close up shots of the brass from my 357 magnum R92, it always has a bit of a bulge around the case head, when you run your fingers you can feel it. These cases are from once fired factory ammo. I fired some of the same ammo in my smith and wesson 357 revolver and the cases are totally smooth, you can't feel or see where the case head is, its all the same. I've been shooting the R92 for years now and when I run it through the sizer die it irons out that little bulge, so I don't think its a problem, just very curious to hear thoughts from former R92 users and expert handloaders.

Also something interesting I noticed. The once fired brass from the factory rounds when fired in the Rossi will drop in and out of the cylinders of my smith and wesson revolver. The once fired brass from same factory ammo from my revolver will not go into the chamber of the Rossi. I measured the cases from both and the once fired cases from the Rossi are on average .001 smaller then the cases from the revolver.

Thanks.
Matt

[Ohio3Wheels]

That has the look opf a stretch mark. Make yourself a probe from a paper clip open it up, file a point on the end then bend it 90 degrees. You want to probe the area of the ring and see if you can feel a "groove" on the inside of the case. This kind of stetching ultimately leads to case separations.

It sounds as if you Rossi has a tighter chamber than the S&W.

Make smoke,

[Ohio357MagFan]

Ohio3Wheels,

Thats what I thought, it looks like a stretch mark! When you run your fingernail over the outside of the case, it feels like a bit of a bump, very very slight. I tried the paperclip on the inside of the case, totally smooth.

[Ohio3Wheels]

Is it just a bump from the top going toward the head or is a ridge?

Wonder about the chamber but it seems smaller than your Smith.

Make smoke,

[Ohio357MagFan]

Ohio,

When you run your fingernail from the bottom of the case to the top you can feel where it goes from the case head to the part of the case that holds powder, kinda like your finger goes up a little. Perhaps a better word would be like a ridge. I know it's weird. The chamber in the rossi is very rough and I notice that the part of the case above the case head looses it's glossy and shiny look when it's shot in the Rossi. The chambers in my Smith revolver are really shiny and smooth and the cases stay shiny and glossy completely when they are fired in the smith

[Ohio357MagFan]

I attached a photo of two primers side by side from a box of factory Blazer Brass 158 gr 357 ammo where I shot half the box in the revolver and half in the carbine. It is easy to see which firearm they came from because the primers in the revolver have more centered strikes and the rossi always strikes way off center. Anyways, the primers are always way flatter in the revolver vs the rossi with same loads. As a matter of fact the Rossi NEVER flattens primers for me even when pushed to super hot loads. I measured the brass from the ones shot in the rossi and the ones shot in the revolver, the brass from the Rossi is a little longer, it was averaging 1.288 and the ones fired in the smith revolver averaged about 1.28 OAL, this is before being resized. What does this all mean???

[Ohio3Wheels]

As these are commercial loading and you should be able to figure that the case length is held closer than +/- .008 I would say that they are stretching slightly in the rifle, but I've been told that straight cases can grow without stretching. In straight wall cases stretching generally occurs when the case mouth is held tight to the chamber wall and the head space is enough that the rear of the case stretches back to the bolt face. Minimal case growth can happen with the case solidly held and the brass just flowing forward. I believe this is the case with the 40-65 and 45-70 cases that I find gaining a little length after 4 or 5 firings. Strangely enough this only seems to happen with smokeless loads and not with BP. I have some 10 year old 40-65 cases that were trimmed to length after being formed from 45-70 brass and have never seen a trimmer since.

With in reason off center firing pin strikes don't concern me too much as long as the gun remains consistent. That said it wouldn't hurt to have some one check the head space on your '92. With excess head space the case may be being held against the bolt face by the extractor instead of a solid lock up between the bolt and breach face. It may be that what your seeing is a slight bit of excess head space. Some where on here one of the guys discussed putting tape on the cartridge head and seeing if the rifle will still lock up. I don't remember what he used or how many layers before it was considered bad.

I tinker and when I see something odd with one of my guns I start asking questions and looking for reasons. I think we're in the right place for that. Take care.

Make smoke,

[Ohio357MagFan]

Ohio, I got one huge question though that I'm baffled about. If there was excessive head space on my R92, why do the primers NEVER go flat even with the hottest loads? In that picture the same factory 357 load was shot in the handgun on hte left and hte R92 on the right, look at how the primers are rounded. It's like that with everything I've put through it, even huge dose loads of W296, primer corners always rounded. Actually not much difference between the 38 special load primers and the full house 357 magnum loads

[Ohio3Wheels]

Good question for which I don't have a ready answer. I went back and looked at those two cases and in the picture the revolver case does appear slightly flattened and the '92 one looks to be seated deeper. Not sure why this is so and it may be just the way I'm viewing the picture or some anomaly in the way the electrons got processed.

Make smoke,

[GasGuzzler]

The pin faces are shaped differently. 92 pushes back from big headspace. My 92 pin isn't even straight but the rifle works well.