Powder burn marks down one side of case (8mm Mauser)

[Charlotte the flyer]

Louise did a batch of 8mm tumbling today, we found some cases that had what looked like powder burn marks down one side. The marks remained despite a four hour tumbling session, they were all from the same manufacturer and have the markings R.P 8 mm (8 x 57) on the bottom of the case. Does anyone know what would cause the case to look like this? I'm assuming that it could be over pressure or incorrectly sized. All of the RP cases exhibit exactly the same problem but all of the PPU ones do not. I think the cases may have been given to me fired because AFAIK I've only fired PPU and FN Milsurp but I'd still like to know the cause if anyone knows.

Thanks

Charlotte

[dave_303]

some of my PPU 7.5x54 cases do this, soot up from the neck down. Apparently it's due to the rounds being under-pressured.

[Alpha1]

I think the cases may have been given to me fired because AFAIK I've only fired PPU and FN Milsurp but I'd still like to know the cause if anyone knows.

What on earth does AFAIK mean.

The cause is likely to be under pressure rather than over pressure did you reload them if so what weight bullet did you use and what charge of powder and powder type did you use.

[Blu]

Charlotte, two things, first the brass. Now the books say a too light powder charge will cause the burn on the outside of the case. And they are right.

However, brass vaires in elsaticity from lot to lot, and between makers. Sometimes cases don't seal completely, even with the "proper" powder charge. Also, since the brass seals, and then "springs back" away from the steel of the chamber, it is possible to get gas residue on the cases, at the mouth, with nothing wrong, at all.

Now, cases loose in the chamber, held off center axis by the extractor, could show a mark down one side. A loose chamber is both a problem, and not a problem, depending on the specifics. In fact, guns intended to operate under the worst possible conditions (military arms) are often cut with slightly oversize chambers, because reliablity is preferable to best accuracy.

I've used R.P. cases in my 8mm Mauser and to be honest I wasn't that impressed with them and so switched to PPU, never had a problem since. Try kicking up the charge a grain or two and see what happens.

Blu

[Blu]

Alpha1, "

What on earth does AFAIK mean.

AFAIK means As Far As I Know. Hey mate, you have a computer there. If you aren't sure what something means then look it up, it only takes a minute. Tell you what old son, here's a link to help you out so you won't have to ask any more. http://www.netlingo.com/acronyms.php

We older folks may not like or understand the lingo but in this day and age, well unfortunately it's a case of keep up or go wtfwtf Every days a school day

Blu

[bnz41]

I use R.P brass in both my Mausers never seen that sort of staining, have you checked the case OAL as I found even the new R.P ones over long, so I trimmed them to 2.23 as I say never a problem.

[dromia]

Charlotte, two things, first the brass. Now the books say a too light powder charge will cause the burn on the outside of the case. And they are right.

However, brass vaires in elsaticity from lot to lot, and between makers. Sometimes cases don't seal completely, even with the "proper" powder charge. Also, since the brass seals, and then "springs back" away from the steel of the chamber, it is possible to get gas residue on the cases, at the mouth, with nothing wrong, at all.

Now, cases loose in the chamber, held off center axis by the extractor, could show a mark down one side. A loose chamber is both a problem, and not a problem, depending on the specifics. In fact, guns intended to operate under the worst possible conditions (military arms) are often cut with slightly oversize chambers, because reliablity is preferable to best accuracy.

I've used R.P. cases in my 8mm Mauser and to be honest I wasn't that impressed with them and so switched to PPU, never had a problem since. Try kicking up the charge a grain or two and see what happens.

Blu

Further to the above I would try annealing the neck and shoulder of the cases.

[Charlotte the flyer]

Thanks all.

I haven't had this problem with any factory milsurp or PPU that I've fired and I haven't done any 8mm home loading yet. I wanted to be sure that it was a cartridge problem not a rifle problem. It sounds like they were under-loaded home loads, the brass must have come with the rifle as it did come with a set of Hornady dies. I'll keep any eye out for this happening when I do my first batch in case it does it again.

Thanks

Charlotte.

[Rburro2]

If you need the sooted up ones cleaned deprime them and il stick them through the STM tumbler for ya

[jjvc]

Are you sure its sooting on the case and not annealing?

Joe