trouble with k-31 hand loads


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sig220mw
May 28, 2010, 08:55 PM
Ok here's the deal. I loaded some 7.5x55 for my k-31 using redding dies which according to redding and the web site are designed for the k-31.

I am using privi brass which is new, cci 200 large rifle primers and nosler ballistic tip 125 grain bullets. The powder is H380 with a load out of the hodgdon manual starting at the lowest.

First round didn't feel right and I felt something that felt like powder spitting back and hitting me on the nose.

Upon inspection of the brass there is black burned powder residue on the rim all the way around the case.

I fired 5 shots and 4 did this but 1 out of the five felt ok and hand no residue.

I trimmed my brass prior to loading and have to admit that some were 2.173 instead of 2.175. When I bought the brass most of the ones I measured before resizing were about 2.180 to 2.183 in length so I set out to try to trim to 2.175 and got most of them on the money.

I'm not new to reloading having done it now for about 18 years without any problems until now.

I have heard that the 7.5x55 can be difficult to load and I guess I'm finding that out now.

Also the fired brass looks a little rounded at the shoulder instead of having the uniform angle that it should. The 1 round that was ok looks right.

Any thoughts or help greatly appreciated.

BTW the factory gp11 and privi ammo goes through it just fine.

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solvability
May 28, 2010, 09:02 PM
Are you loading really light loads?

NCsmitty
May 28, 2010, 09:41 PM
It sounds like you're not developing enough pressure to seal the chamber with that charge of ball powder. Probably inconsistent ignition.
I would be using a magnum primer to start with, if I was using ball powder. That's just me.
I've read other posts indicating extruded powders often give the best accuracy in the 7.5x55.


NCsmitty

sig220mw
May 29, 2010, 12:12 AM
The load was 44 grains of H380 with a cci 200 large rifle primer. the second load was 44.5 grains of same. I also had some loads made up with H4831 but didn't get to them since I stopped when this happened. The 4831 is extruded and the starting published loads start at 49 grains which should give better ignition with the case being closer to full.

Maybe I will try the mag primers as suggested by NCsmitty. Do you think I should try it with the 4831 also or just the 380?

parker51
May 29, 2010, 03:31 AM
I never could develop a decent load for the K31 using a bullet under 150grs. I am currently using 44.grs of Varget (Nosler 150gr BT) and 43.5grs of IMR 4064 (Nosler 165gr BT) with excellent results in several of these rifles. I must have loaded a couple hundred 125gr BT's and couldn't get any to group at better than 2" at 100yds. I think this may have something to due with the distance of the bullet to the start of the lands. The GP-11 bullets are 174grs and much longer than the 125gr BT's. If you are just shooting targets I would suggest you try either the 150gr or 168gr bullets. As for primers, I use CCI and Win LR primers with the 2 powders mentioned. Hope this helps.

NuJudge
May 29, 2010, 07:41 AM
For the K31, I've had best luck with slow powders in the 4831 class, although recently I've had excellent results with 4064.

In my experience, K31 barrels have wanted different bullets. When relatively new, the best results I ever got was with the Remington bulk 165 softpoint. Only after a lot of shooting am I getting decent results with 168gr match bullets.

CDD

sig220mw
May 30, 2010, 04:38 PM
OK thanks for the input.

It looks like maybe I need to go to the heavier bullets and the 4831 powder. As I said in my 2nd post, I had some cases loaded with the same bullet but with the h4831 powder. Now I think I'll pull those and use the same 4831 but with a 165 or 168 grn bullet.

The odd thing about it was that one out of the five shots fired did ok as far as how it felt and how the brass looked.

I'll try the heavier bullets with 4831 and report back later.

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