I have a neat old Winchester 1895 in 30-03 caliber. From what I have read, the only difference between the 03 case and the 06 case was neck length. When I first got the rifle, I tried 30-06 in it but only a couple of rounds since the primers were backing out about half their thickness and it made me nervous. I took the rifle to a gunsmith to have him check the headspace and the rifle easily chambered the no go and field gauges. He said no worry as he had an adjustable micrometer type gauge. After several tries and having the gauge at its maximum length, we were still not able to measure headspace! So somewhere in excess of .035".
So, I acquired a small amount of .280 Remington brass and opened the neck up to .30 cal. The empty cases chambered just fine in the rifle. I had some 215gr lead bullets with gas checks and have loaded them into the cases with 12.5gr Unique. I wanted to load them long so that the bullet touched the rifling and closing the action would force the bullet into the case a bit and keep the base of the cartridge tight against the bolt face. It seems that is not possible as the loaded cartridges are at the max length to fit into the open action and the action will close easily without changing their length. There is maybe just .125" of bullet in the case neck so not even possible to make them longer.
So my question is, do you think what I have now will fire form to eliminate the headspace issue? I am going to the range tomorrow to try them.