Headspace issues?

[300backfire]

I've got a Mauser 96 stigma in 6.5x55. This things got me stumped,and I need some opinions. I shoot factory ammo and the primer backs out. This tells me I have a headspace issue. Yet if I shoot reloads,45 gr re22 under 140gr bullet primer stays in, but I have blow by over half way down the case. This tells me my loads not hot enough to seal the chamber. Yet it's getting on the warm side for this gun. No blow by on factory. I've stripped the bolt.and proceeded with scotch tape on the rear of the casing. On the 3rd piece I could just start to feal resistance. Measured it at 4thou. That should be ok isn't it? Anyone got any ideas? Factory ammo is downloaded so bad, could low pressures cause a primer to back out? Should I try a faster burning powder? Would this help to seal the chamber or should I just keep working a load up hotter.

[qwert]

I suggest you borrow or buy a proper hardened headspace GO gauge (~$25) and use the tape method you are now using to estimate actual headspace. A chat or visit with a good gunsmith is always worthwhile, some will prefer you to strip the firing pin and extractor (and certainly remove any bolt mounted ejector) from the bolt before checking headspace.

If your rifle is safe to fire but has long headspace, you can solve a lot of problems by reloading using proper die adjustment to minimize shoulder bump.

Good Luck, YMMV

[marxman]

I use magnum primers in 6.5 55 still probly you need faster powder to raise the pressure quicker maybe its a bigger chamber all the way around i would adjust my die and use a faster powder

[260 Rem]

Once the factory brass is fired in the chamber, the once fired brass should be properly headspaced as the shoulder should be blown forward. If, using a FL resizing die that was a bit "tight," and also bumping the shoulder back too far ..it could cause issues. However, if you have used the die with no issues before, the tight die theory is probably not the cause. Neck sizing only should eliminate that theory as well. Really, I have no idea
Have you tried a primer with a hard cup like CCI - BR 2?

[300backfire]

WLR is the only primer I've used as of now. Once fired brass measures one thou bigger than factory. So if I've got an oversized chamber, it's not blowing out proper due to lack of pressure. But they seem quite uniform so I'm thinking chamber is ok. I've loaded a couple more boxes and just neck sized. As I'm typing I'm also remembering I used federal brass and forgot to kick back a grain due to really thick brass. Now I got to take them all apart. Anyway if it warms up a bit tomorrow I'll try it out. Next step I'll try some 4064 and varget if that don't work. Try to get it to a smith this weekend for proper headspace check

[DaleJ]

Why not expand neck to .277" and then size in 6.5 X 55 die in small increments until bolt just closes with cartridge in chamber? That will prevent brass stretch from over-sizing. That is also the position you should set the sizing die lock ring at.

[300backfire]

I was wrong, I just measured again and after shooting there 9 thou bigger just behind the shoulder. Yes I will resize necks to .277. 260 had suggested that last week and I forgot. What I can't figure out is why a low pressure factory will seal the chamber and a hotter reload won't. The more I think mag primer the more sense that makes. Same as faster powder

[DaleJ]

Originally Posted by 300backfire

I was wrong, I just measured again and after shooting there 9 thou bigger just behind the shoulder. Yes I will resize necks to .277. 260 had suggested that last week and I forgot. What I can't figure out is why a low pressure factory will seal the chamber and a hotter reload won't. The more I think mag primer the more sense that makes. Same as faster powder

Make one change at a time so you can identify the "fix". If fired cartridge necks and shoulders are soot coated try a faster powder. The load you mentioned in first post should have enough pressure to seal case necks.

[marxman]

Originally Posted by 300backfire

I was wrong, I just measured again and after shooting there 9 thou bigger just behind the shoulder. Yes I will resize necks to .277. 260 had suggested that last week and I forgot. What I can't figure out is why a low pressure factory will seal the chamber and a hotter reload won't. The more I think mag primer the more sense that makes. Same as faster powder

Your sized case might not be the same dimension as factory and they probably use a faster powder to make up for low load density sqishiness and the same blowby problem you have. If you have blowby either its low pressure or the pressure is rising too slow. I had that problem with 4895 in 30 30 switched to rl 7 no problem

[Pathfinder76]

Lug setback is a real possibility with this action.

[300backfire]

I just loaded same load with cci mag primers, some with stepped neck and WLR primers and others with imr4064. I'll try these out today and see what happens

[kayaker]

Your ex-mil chamber might indeed be larger.

In my T3 I have shot numerous 140gr bullets over 45gr RE22 and CCI200's and get a sooty neck but have never had blow back half way down the case.

[DaleJ]

Originally Posted by kayaker

Your ex-mil chamber might indeed be larger.

In my T3 I have shot numerous 140gr bullets over 45gr RE22 and CCI200's and get a sooty neck but have never had blow back half way down the case.

Your T3 will be 6.5 X 55 SE. The SE designates a higher pressure round. Vihtavuori's on-line load manual has the "SE" data. You could safely warm your load up quite a bit for the T3.

[rembo]

Originally Posted by kayaker

Your ex-mil chamber might indeed be larger.

In my T3 I have shot numerous 140gr bullets over 45gr RE22 and CCI200's and get a sooty neck but have never had blow back half way down the case.

Dale is correct.

I used to run 48 grs of Rel22 under a 140 AMax in a Sako 75 6.5 x 55