7/300WSM Case Capacity and Forming

[300magman]

But I like it like this(brass should last forever)

That's what I was thinking, I'm not sure how much longevity I will gain, but I'm sure the sharper shoulder will stop the brass from growing so fast.


And looking at the case capacity without the neck included, there is a nice little grain of about 1.5gr I think if I stretch the length a bit further, and knock the shoulder out to 0.535, I could get it to a full 2gr extra space and still have a neck that is 0.286" long.


It would still be well short of the WSM case capacity (which is what I want) and have a much longer neck than the WSM, but with a sharper shoulder for slower case growth and enough capacity to hit some very respectable velocities.

 

[Mikecr]

Here is a before/after improving of a 7saum
I took the neck to .286, shoulder to .535, and 40deg. Adjusted capacity view for 15thou body taper w/o bullet.
I only mind total H20 capacity (to case mouths), because that's what I measure & enter into QL(which subtracts bullet volume for whatever bullet& seating I'm using).

This is where software is superior to manuals.
I could take measurements on brass in hand, draw the case, fill out a reamer print, draw estimated fireformed, run 'what-if loads' with various bullets/parameters.
Twice now, when I got to the point of H20 capacity checks, I found that I was right on the money, and given that I don't FL size, and my powder files were adjusted by lot, my QL predictions have held within 10fps. I can even estimate my max pressure, as I'll see with calipers on the webs, during fireforming.
This, before ordering barrels, reamers, dies, etc.