I don't have a 30-378, but I have a Mod 70 in 300 RUM that I load to the nuts. I have a Bushnell 6500 4.5-30 on it since it was new in 02. Have put a lot of rounds through it and it has never changed zero since I sighted it in. And I don't use a brake either.

Last edited by BluMtn; 01/27/21.
Writing from the gateway to the great BluMtns in southeastern Washington.

Just remember, "You are the trailer park and I am the tornado". Beth Dutton, Yellowstone.