Brass question


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armoredman
December 24, 2005, 10:13 AM
Yesterday I finally fired my first ever 7.62x54R reloads, and the resulting brass has me scratching my head. First, I have a mixture of Winchester, Lapua, and S&B brass, all in thier second loading.
I fired the rounds, (not very heartening, best group was 3 inches at 100 yards, the worst I refuse to talk about), and brought the cases home. Extraction and ejection was easy and normal, better than the surplus stuff by far! Oh, rifle was 1943 Mosin M38, rearsenalled to near excellent, head spaced some time ago by coin gauge, well within normal, good shooter.
All the brass was tumbled, resized/decapped, and tumbled again- I like shiny.
Then, as I was reinspecting, (one had a split case neck, dadgumit - this stuff is hard to find.), I discovered two things interesting.
1) Every single case had a bright shiny mark evenly around the case bottom extending from the rim up .15 inch. Chamber stretch? Normal? Never saw it in the surplus, but steel doesn't stretch like brass....
2)When rubbing along the case necks, I discovered each and every one had an odd raised mark almost all the way around every single case neck, where is goes into the ogive from the case body, almost as it is had been originally welded on. The few cases I did not load do not exhibit this mark. I full length resized all cases, so I wonder if I either did not set the die right, and only neck sized, and this mark is fireforming from the chamber, (no troubles with any ammo fired before but some Hungarian surplus split case bodies), or did I ruin each case with a overload, even though I measured each powder charge individually.
The loads were the starting load listed on the Lee sheet that came with the dies, 50gr H-335 under a 125gr SP .310 bullet. I plan on downloading to 45gr, as these loads seemed stuffer than the surplus Czech Silvertip I fired for comparison.
I like to think this is no big deal, but my cheapie Russki rifle is my only rifle, and my two eyes are my original issue, and I would like to keep all three in working order.
Any thoughts?
I'll post this on a few boards to see what responses I recieve from you guys. Thanks a bunch.

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Khornet
December 24, 2005, 10:19 AM
That ring at the base sounds like a sign of incipient case head separation, which means either you over-sized and pushed the shoulder too far back, or the headspace isn't right after all.

They say you can use a bent paper clip as a feeler inside the case, feeling for a groove around the inside near the base, which if present is a sure sign of coming case head separation. The neck thing you describe I don't understand.

My 2,000th post, I believe!

deadin
December 24, 2005, 10:39 AM
As the M-N headspaces on the rim, a little shoulder set-back shouldn't make much difference. Any other signs of pressure, like flattened or loose primers?
I would definitely do the paper-clip test that khornet suggested. However it also could be as simple as the fact that sizing dies don't size the case all the way down to the rim and sometimes leave what appears to be a little "ring" at the head of the case. (There are "small-based" dies available for some of the calibers that Browning autos use that size further down to the head. This is because of a functiong problem in some the Brownings with regular sized cases.)
The case neck "bump" could be anything from an improperly adjusted die to an abnormality in the chamber. Your guess is as good as mine.

Dean

The Bushmaster
December 24, 2005, 11:09 AM
Can you furnish a photo? I have no comment unless I can see for myself. and then it would be heresay.

Usually the ring that Deadin discribes is not so bright when it's made by a resizing die. So if it's really bright I might worry.:uhoh:

Photo, if you can, please...

armoredman
December 24, 2005, 03:21 PM
i used a paper clip as described both here and in one of my manuals, and there is no stretching inside the cases I can feel. I'll powderpuff load these, and buy some more factory for new brass, maybe next week - everyone seems to be out of 7.62x54R brass reloadable....

5.56
December 24, 2005, 04:30 PM
The ring sounds very much like it is a case streatching due to the bolt holding the round in position with too much headspace. The brass fireforms to the chamber streatching the case material. The ring is where the brass flowed from to allow the case to fire form to the chamber. Now if that is the case, you might want to invest in a neck sizer die. The case has been fire formed to match your rifle. A full lenth resizing and trimming will result in fire forming again and risking case failure or weakening the case at the very least. You can full lenth resize one that has been fired and check case length to see if indeed it has fire formed. With a full length resize it will need to be trimmed alot I am sure to bring it back into normal specs. Just my humble opinion is all.
One thing you can also do is to use a hack saw on a fired case and split it, you can then see and mike the area in question. Good luck.

5.56

Archie
December 24, 2005, 05:18 PM
With a new - or at least unstretched - case or three, load up some starting level loads, and seat the bullet far enough out to touch the rifling. What you are doing is keeping the base of the case against the bolt face, thereby eliminating any 'slop' in the chamber.

Fire two to five such rounds.

Then compare those cases to the other cases. See if they've stretched more or less; see if they've acquired the bright ring around the base. If they show no stretching compared to the cases you've described, you have excessive headspace.

However, if you fireform all your brass as I've described, and then neck size only, it won't matter. (This proceedure results in a family of cartridges known as the ' Cheapskate Archie Improved' wildcat.)

The only concern after this is if the headspace keeps growing. If it does, something is very wrong with the locking system.

The boo-boo at the neck is around the circumference of the case? Not from the neck to the mouth, right? Like Bushmaster said, a photo is most helpful; but offhand it sounds like a boo-boo in the chamber.

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