7mm sherman max

Well, the first 7mm Sherman Max was born 5/25/19 at 8:31 a.m. and weighed in at 8 lbs 5oz. Havent determined sex yet but no one cares these days anyway!
Rhian/Bigngreen spun this baby up so it should be a shooter.
He fire formed a few brass that I sent him just to get a little initial data. Here is what he learned thus far:
The cases shrunk .006" average when forming and were very uniform in shrinkage. I set the chamber length exactly at new brass length so first firing will give .006" trim.
Loaded neck o d was .316" so chamber clearance will be .004";also good.
Case capacity formed was 77.4 grains; pretty much as predicted.
Velocity with 180 hybrid reached 3071' with more left according to Rhian, and primer pocket as snug as new.So far so good and might I add the case is "mean sexy" looking!!
30304.jpeg
 
Last edited:
The case in the picture without writing is an unformed SAUM case for comparison, I had not planned on chambering one up but had a couple hours and a HCA carbon barrel sitting in the corner with nothing to do so I spun it up on the ol test mule.
Fire forming at nearing full loads is a rough thing to do to new brass but it looks good and primed good after this first round:)
 
Well, the first 7mm Sherman Max was born 5/25/19 at 8:31 a.m. and weighed in at 8 lbs 5oz. Havent determined sex yet but no one cares these days anyway!
Rhian/Bigngreen spun this baby up so it should be a shooter.
He fire formed a few brass that I sent him just to get a little initial data. Here is what he learned thus far:
The cases shrunk .006" average when forming and were very uniform in shrinkage. I set the chamber length exactly at new brass length so first firing will give .006" trim.
Loaded neck o d was .316" so chamber clearance will be .004";also good.
Case capacity formed was 77.4 grains; pretty much as predicted.
Velocity with 180 hybrid reached 3071' with more left according to Rhian, and primer pocket as snug as new.So far so good and might I add the case is "mean sexy" looking!!View attachment 135383
What powder was this with Rich?
 

Recent Posts

Top