Split shoulders

[rvpilot76]

Brass is new reformed 284 WIN for my K31 Swiss. Load is 45 grains of IMR 4320 (loaded by my dad). Weird thing is, rounds 1-6 didn't split, but 7-9 did. I stopped shooting upon finding the necks this way. I just got this rifle; I hope it wasn't sold because it's a lemon. I can't imagine that, being that it's a K31 Swiss. Also, primers are neither flattened nor cratered, and the shoulders look like they are in the same position before and after firing. My 303 Brit fireforms with the shoulders moving forward quite a bit (normal), but I've never lost a case during the fireforming process. Not exactly sure why the shoulders are splitting; this is a new one for me. Thanks for help with this problem, fellas.

Kevin

[jhrosier]

Kevin,
The K31 chamber is larger in the shoulder than the earlier rifles.
Some die sets are made to the correct size for the K31 chamber and others are made to the smaller spec.
Sorry, i can't recall which brand is cut for either, but someone here will know.
I can tell you that I have fireformed cases in other calibers that were greatly undersized in the shoulder area with no problems and the cases worked fine on subsequent firings.
I use a small charge of Unique under a case full to the top with cream of wheat and topped with a bit of kleenex or paper towel.

Jack

[rvpilot76]

http://i13.photobucket.com/albums/a271/rvpilot76/100_1587.jpg

Hmmmm...

Kevin

[462]

Can't help you, other than maybe the brass was over-worked when the initial re-sizing was done.

I understand that Lee uses the 1911 chamber dimensions, while Hornady uses those of the K-31. I understand, too, that the people who use Lee dies don't experience problems.

I use Lee neck-sizing dies and Norma brass and have never had a problem from either of the two rifles.

I use IMR 4895 with jacketed and Unique when shooting boolits, with .308 Winchester recipies as a guideline.

[runfiverun]

rcbs dies are the ones for the k-31 the others are cut for the 98-11.
the 7.5x55 started out as a x53 then went to x54 and finally to x55 but the shoulders moved slightly also.
to avoid this when i make mine from 284 brass i usually go for a crush fit or a donut on the neck.
i see a line halfway up those cases where they would have split on your next firing.
remember iirc the 284 has a 20* or 22* shoulder angle and the 7.5 is 30* or the other way around,any ways it messes up right there.

[oneokie]

Maybe anneal the necks?

[chuebner]

Redding, not RCBS, makes the correct 7.5X55 Swiss die set that is correct for the K31. I lightly annealed the last batch of 284 Win. cases I converted to 7.5 Swiss just to make life easier on myself. Imperial sizing Die Wax makes the process a lot easier also. Fireforming is done with 10gr. of Unique under the Lee C309-160 sized to .309. Cases are then only neck-sized with the Lee collet die for 7.5 Swiss.

charlie

[rvpilot76]

Talked it over with the 'ol man, and as posted above, we think the brass just needs to be annealed. Dad said this particular bag of 284 brass necked up with more difficulty than the others. Thanks to all who chimed in.

Kevin

[rvpilot76]

i see a line halfway up those cases where they would have split on your next firing.

I asked Dad about this as well, and he said it's from the ammo rattling around in the MTM ammo box (the 50 rounder). Makes sense when you think about it.

[chevyiron420]

I just lost about half of my 6.5 carcano rounds to the same thing. I made them from 220 swift brass and should have annealed them but i didnt. I know better esp. with winchester brass.

[Baron von Trollwhack]

The easy way to tell what dies you have , 1911 or k-31 is to simply measure the diameter at the case-shoulder transition. Lee DID make K-11 dies for quite a while, before starting to make the K-31 dies. Your shoulder splits suggest k-11 dies were used to load brass to fire in the K-31 chamber, thus brass folding in on forming and splitting on firing. Redding made K-11 dies also till they transitioned (under the same stock number---DANG IT) to correct K-31 dimensions. Before K-31 imports, there were mostly only a few of the K-11s and earlier available, thus no need for the K-31 dies. You have to know throating was vastly different too. K-11 and earlier throating for a big fat RN bullet, K-31 short throating for the low\drag spitzers. BvT

[Jim]

I'm not sure, but from the looks of the cracks, it appears that there were excessive lube wrinkles in the shoulders. Upon firing, the wrinkle had no where to go and seperated. I've had this happen. I figured the case would fill out on fire forming and did not.

[badgeredd]

Talked it over with the 'ol man, and as posted above, we think the brass just needs to be annealed. Dad said this particular bag of 284 brass necked up with more difficulty than the others. Thanks to all who chimed in.

Kevin

I agree with your thought that they needed to be annealed. IMHO, I'd also guess that you may need to form an over-sized area at the base of the neck also. I had a similar problem forming so 6mm TCU cartridges and found that they were moving fore and aft when fired causing the neck/shoulder area to try to form twice on firing. By over-sizing the neck and then down sizing it to 6mm I left a mini shoulder at the neck base that stopped the problem. I also use a stout charge of Unigue with COW and tissue to fireform as it seems to form a bit better.

Edd