Case capacity gained with improved cartridges

Len Backus · #1 01-09-2004, 10:58 AM

After doing some more careful measuring, it looks as if my 7 Lapua Improved project will net me somewhere around a 6 grain increase in nominal powder capacity over that of a 7 RUM. That's good enough for me, especially with the advantage gained in brass quality.

The increase gained with the various 30/338 Lapuas of our members over the parent case seems to be somewhere around 7 grains. I would be most interested to learn of the amount of gains achieved with other common "improved' cartridge projects. Who has good data on the 300 Tomahawk project, before and after?

Darryl Cassel · #2 01-09-2004, 03:44 PM

Len

Tomahawk #1 can give you more info on that.
He and Ray Romain was instrumental in the design of that one.
I simply used the reamer that was ordered.

The neck jucture looks the same length but the shoulder is blown out and the shoulder angle is 35 degrees.

Tom #1 will be around soon I'm sure.

Later
DC [img]images/icons/smile.gif[/img]

tomahawk #1 · #3 01-09-2004, 05:07 PM

Len

The shoulder on the 300 ultra is .520 and the shoulder on the Tomahawk is .535 which gives you a 5 degree body taper with a 35 degree shoulder. Neck length is .286
Hope this info helps with your reamer development

Tomahawk#1

Len Backus · #4 01-09-2004, 05:47 PM

Tomahawk

Thanks!

I assume the shoulder/body junction had to stay where it was?

dwm · #5 01-09-2004, 06:17 PM

Len,

What powder are you planning to burn in this really big 7mm case?

Are you planning on having a long neck on the case to keep the throat from buning out or counting on really slow burning powder to help out with that problem?

I have read some posts on here on LRH.com about rapid throat errosion with the big 7mms.

Just wondering if you had a plan in the design of this case which would help this issue out.

Doug

Len Backus · #6 01-09-2004, 06:55 PM

dwm

I'll use one of the slowest powders, of course. And I'll just re-barrel every few hundred rounds. [img]images/icons/smile.gif[/img]

4mesh063 · #7 01-09-2004, 07:37 PM

Len,

if you want to increase the capacity and are looking for a big "improvement", just increase the diameter at the shoulder and you'll gain a ton more than all this 40 degree crap. (do that too) Do away with all but about 3-4 thou of taper per inch and the cases wil eject just the same and the capacity will be LOADS bigger.