A 7-30 and 7X57 aren't even remotely related. The cases are completely different, and the 7X57 is about 500 fps faster.
I see that sarcasm is utterly lost on you ;-)
Back to the OP. I went through a spell where I would get all starry eyed for a particular oddball cartridge and would spend all kinds of money building guns, working loads, buying the best components and researching to the nines.
But then one day I realized something.
A piece of brass is just a piece of brass one isn't really any more special than the other because of its shape. All they do is hold some powder, a bullet and primer in the proper locations to go BANG and put a hole in a target. Something EVERY metallic rifle cartridge mankind has ever devised manages to do.
Once I realized this the wildcats and oddballs quickly lost their appeal to me and I merely became a CALIBER fan (as in bullet diameter) and started buying the simple tried and true cartridges in those calibers in the platforms I wanted and loaded them up or down depending on what I wanted to do.
Hence it's a heck of a lot easier and cheaper to load a bolt action 7x57 to mimic a 7/30 than it is to build a strong 7-30 bolt action and try to turn it into a 7x57 (or 7-08)
The only conceivable exception is if you have an ENCORE and already load for 7-30 would be to order a MGM barrel in that chambering. But again you could just get a $200 7/08 barrel, download and disavow yourself of the belief that the BANG and resulting hole in the target would be actually any different were you using a 7-30 case.
