Primers Backing Out

[Contenderizer]

I haven't reloaded in many years, so pardon this rather academic question. I have a box of 8X56 Mann/Scho that I purchased from Old Western Scrounger some years ago. After firing a few rounds I noticed that the primers were backing out (I have no means of measuring same, but enough to see, and easily feel when running you finger across the head). If memory serves me correctly, this is an indication of a light load - prehaps a little too light. I have fired other ammo in this gun without this problem, so I assume head space is not the issue. It wouldn't surprise me if OWS has errored on the light side to play it safe ... given the age of these guns. Any other possibilities? Thanks.

[L. Cooper]

I think primers backing out is most often a sign of headspace problems. I believe mild loads can contribute to similar problems, but if the headspace is correct, the primer should be supported by the bolt face and get no farther out than flush.

My first step would be to actually measure the headspace.

[Dan Morris]

Could also be high pressure.... I'd also mike the cases!If you relload, how many times have the cases been loaded?
Dan

[Hammerforged]

If it was my gun I would check the head spacing to be sure, then work up loads that are higher pressure. I have never had a backing out problem with high pressure, moderate to heavy loads in any cartridge. I have had only one instance where the primers were backing out. This was with Remington factory loaded ammunition in .257 Roberts. We all know that they try to keep pressures low in this cartridge for the old small ring designs of Mauser rifles.

Are you getting any blow-by (soot around the case)?

[Jack]

Contenderizer, first, welcome to HuntChat !
In answer to your question, you could be correct that the loads are on the light side, causing primers to back out.
Or, the primers backing out could be a sign of excess headspace, too- or both.
Simple, huh?
If it were my rifle, I would take the rifle, ammo, and fired cases to a gunsmith who had a set of headspace guages for the 8x56 MS. (not every gunsmith may have the gauges for that caliber). Have him measure the headspace. Should be cheaper than buying the gauges yourself.
I suspect your headspace might be on the large side, but acceptable- but it would ease my mind to know for sure, if it were my rifle.

[Catfish]

I believe that you have to have lite loads and bad head spaceing for this to occur. I have fire many rounds while fire forming brass that I knew the head spaceing was off when I fired them, but when fired with stiff loads the case come out prorerly head spaced and if alittle to stiff the primer will be flattened but still flush with the head of the bullet. I have also found over the years that you cannot fire form with loads that are loaded to lite, which is in essance what you are doing with these loads.

[Rocky Raab]

Dittoes on the welcome (great screen name, bud!)

I'd lean to the to-light load side of the discussion - especially as you've fired other loads without a problem. I'd suspect -as you did- that OWS loaded them light to be safe in some of the creaky old rifles still around for that chambering.

Reload them in the usual way, and I'd bet that even start-level loads fix the problem.

[Contenderizer]

I appreciate the info gentlemen. I guess I'll try to find a gunsmith with the proper tools to measure headspace on the old 8X56. It might take awhile, but I'm in no hurry. Thanks again.

[happyscrounger]

I think this comment may have come a little late but late is better than never.
could it be that when you sized the case you could have set the shoulder back to far causing what seems to be a headspace problem?