Originally Posted by
Catchem
Thanks to all for your feedback.
My interest is limited to seeing how high SAFE reloads for the 257 R and 7x57 Mauser can be made. Both have low SAAMI specs, and both safely could be shot faster.
257R +P = 58,000
7x57 = 51,000
6 MM Rem= 65,000
It seems to me at first glance that a bullet with a given S.D./velocity/pressure relationship in 6 mm Rem in a reloading manual would be shot at the same velocity/pressure in the other 2 as long as the S.D. and type of powder was held constant. By using a chronograph and going up slowly performance of the calibers would be improved safely(?).
I realize that theory and practice don't always match up.
Based on that I would say no....using another caliber to gauge reloads probably isn't a good idea. As a few said, the only safe way to do this would be to slowly build up loads using classic methods signs of high pressure like proud primers, stiff/tight bolts upon case extraction, cracked cases, etc...also using a crony would be a good idea as well to check for consistency, a lack of which may indicate high pressure.
I have a 257 Roberts AI I recently built and am in the same boat of having to slowly build up a load watching for signs of pressure.
Just remember...speed doesn't always equate to accuracy....I build accurate loads watching for signs of pressure.