I have a Turk mauser with excess headspace, it pushes out primers. I trimmed some 30-06 brass and sized it until it just chambered. This was a lot of work!

What about using my 8*57 brass with light loads and a bullet jamming the lands? Safe, effective? load suggestion for fireforming?

Is there a better way, until I can rebarrel?

Take your 8x57 brass and run it over a .338 or .358 expanderball then size it down so it just chambers and fireform.
Lyle

If you oil the cases before firing they will fill the chamber. Then size until only a little neck is unsized. The likely reason the primers protrude is that you have been shooting the low pressure comercial loadings. Thewy are about like 32 specials but produce less pressure due to the larger case.
Good luck!

Check inside your cases with a feeler wire for insipiant head separations.

It's a lot of work but the only safe alternative is to have the barrel set back or rechambered to say 8mm/06.

One of my good shooters is a 270 with headspace and I make brass out of 280's. Everything has a cost.