Clark the rails are different on a pre 64 M70 308. The cartridge is short,and the magazine is blocked for the short case. The rails are tuned to the short magazine and cartridge.
When you go to a 30/06 cartridge, you have to remove the short box and replace it with a 30/06 box and follower. But the rails remain the same and the longer case will pop free of the rails "sooner" than they will on are 64 action set up for a 270 or 30/06.
You might think there is not much difference by looking at it, but it's there and and you don't get a feel for these things by looking. You gotta "do" and I "did" and would not do it again.
The case will be a lot further back as it jumps free of the rails. If you re lucky the rim will jump under the extractor for you way back there. And hopefully the case will be aligned for easy passage into the chamber. Personally in going from 308 to 270 I did not like the arrangement at all and would not do it again. But that's your call.
I don't know a way to add metal and regrind rails to better accommodate the longer case. Seems like a lot of work. You will see if you do it that the bolt is only about half way forward when that 25/06 will jump up off the rails into the raceway. Hopefully the rim will be grabbed by the extractor and be properly aligned for passage into the chamber but it looks and feel 'sloppy" since the front of the cartridge may or may not be aligned for passage into the chamber.
If Winchester wanted the longer case popping up that far back they would have arranged that in the rails of the 30/06 based cases way back in 1937.Pre 64 rails are cartridge specific, and given the function history of the pre 64 M70 (pretty much perfection), I am not going to second guess the pre 64 engineers. When it comes to bolt cycling they got it right the first time, If they wanted 308 rails for 30/06 cartridges they would have set them up that way in the first place. They didn't.
I am a function Nazi and did not like the arrangement. It was junk.
Personally if it were mine I'd rebarrel to 243, get a fast twist tube for it to shoot the heavy 6mm bullets and forget the 25/06.
But that's OK. There are plenty of guys who thought they could second guess Winchester engineers and there are plenty of screwed up pre 64 actions out there. Might as well add one more...
It's Mickey Mouse.
You can do it if you like. Good luck.
If you still have the 308 box in the rifle how did you test the 6.5/06 to know that it "fed just fine"? A loaded round won't fit a 308 box(?)
And what is stuck that you can't get out?
