Originally Posted by gamedog
I'd leave the 30-378 as is. Get a 338 if you want to shoot heavier bullets. The 378 case is pushing that bullet rather well , but at the expense of powder and barrels. Stepping up further into a 416 case would exaggerate that even worse.
I have to go along with Gamedog. I have both ( A 30/378 and a 338) and
they each have there purpose.
The 30/378 is very fast with a 200gr bullet out of a 27" tube and the 338
shoots the 250gr AB and the 300gr SMK very well.
My 200gr load for the 30/378 pushes it 3273ft/sec and groups .091 5 shots
@ 100yrds with 114 grs of 50 BMG.
With 7 more inches of tube you should gain 150 to 200ft/sec more. And
with 126 to 132grs capicity the potential is there for the 225gr and the
At one time powders were to fast for the 30/370 and even though there
are slower powders now it's hard to utilize the case to its fullest,So going
to a bigger case does'nt gain you much. and barrel throat life is very short
(Arround 200rds some erosion has already started.
I was going to blow out the shoulders to 40o for more case capicity
but changed my mind after loading for it.
Try it first and I dont think you will be disapointed, The brass even though
it is expensive it is still cheaper than custom brass.
J E CUSTOM