Here's my progress, so far. I could've easily messed-up the math, because it's tedious and I don't have the RCBS program (which is still over $100 at Natchez). I used the web page calculator at the website

http://kwk.us/cases.html to reduce the math required of me, once I figured out the remaining case dimensions.

I haven't done any Quickload runs yet, but I think this 7mm GT wildcat will be powder-constrained; I came up with 64.8 water grains capacity. For comparison, QL data has 66.0 grains for a 284 Win case.

Here are the highlights from my calculations. I used the numbers from the SAMMI

7mm WSM print as the starting point.

http://www.saami.org/PubResources/CC...t%20Magnum.pdf
Looking at the shoulder position, 1.8565" - 1.57" = .2865. Did you swizzle a couple of digits, Travis?

One thing that prints don't show, but is needed for the case capacity calculator, is what I'll call the head to body taper length. The angle is 45'-6'' on the print. I come up with a length of .03737" using the published angle. Add this number to the head (.054") and extraction groove (.040") lengths and the case body is found to start at .131 inches--at least for the purposes of using the capacity calculator web page.

Doing the trig (I'm too lazy to reproduce my napkin scratches here), I get:

....................................

__7mmGT__.......................

__7WSM__
shoulder length =...........0.12614".......................0.1547"

shoulder position =.........1.44386".......................1.7018"

shoulder dia. at body =....0.53269".......................0.5377"

neck position =...................1.57".......................1. 8565"

The remaining numbers should be the same for the two cartridges.

The case capacity calculator says,

*If you have a rimless cartridge, enter for the rim the inner diameter and the average width of the extractor groove. A correction is made for the primer pocket.*
I'm not exactly sure what is meant there, but I got the best correlation with the Quickload value for 7WSM when I subtracted the .131" for the total case head length from the position values. The case head doesn't hold much powder and my website calculator result agrees well with the 7WSM capacity value from QL (81.1 grains). I don't have any actual cases to measure with water and a scale.

Using the same method for the 7mmGT:

The greatly reduced case capacity is due, of course, to the much shorter case length. Also notice that the body taper of the 7mmGT is actually more than the 7mmWSM. The 40' shoulder angle doesn't help much to increase case capacity by maximizing body length volume.

I'll try some QL runs when I get a chance.

-Cal