Originally Posted by 300whisper
Alright guys please forgive my newbness here and I don't mean to thread high jack, but the 7mmRM is based on the 375H&H as a parent case and so is the 300WM. So, isn't a 7mmRM the same as a 7mmx300WM? Is there a steeper shoulder or more/less taper on the case? I agree with major that those published FPS fills a nice niche but where does that extra velocity to edge out the 7mmRM come from? I see why the OP built his rifle on this round bc I am now really interested in it as well. Thanks guys.
This round is a 300win mag case with the same shoulder angles, just necked down to 7mm. I really simple wildcat really. You are correct about the cases, but the 300win mag's dimensions allow for just a little bit more case capacity that seems to give those 180's just a hair of a boost. For instance I rund 71.5gr of H1000 for my 168 bergers, this is over max by hodgdon standards. I coudl probably only get another grain at the most of powder in that case. With the 7/300, with the same powder, I have read guys using 76-79gr of the same powder. The case is just big enough to give you that little extra boost, plus there have been pretty good reports of barrel life from this gun. Doesn't seem to be too wild of a barrel burner from what I am understanding. Hopefully this clarifies a few questions for you.