Heyo folks,


Been screwing around with the 7mm Mauser and thought, "What if the Germans during WWII decided to give the 7mm Mauser the Kurz treatment?" So lo and behold I decided to do it via image editor. What I need help in is finding out the potential ballistics. My guestimates put it between the 7.62x39 and 6.8 SPC in terms of ballistic performance, but I am a complete rookie for this.






Here is the cartridge I decided to make because I felt like it. The only thing that has been changed is the size of the bullet and the case length. The shoulder and neck are unchanged. The top cartridge is using a 160-grain projectile. The Kurzer's case length is 41.2mm, which is practically the only factor that changed. I appreciate any help you guys could provide. 

OP has no idea of how German Squad tactics at the time worked.

Well not all of us made it past middle school reading comprehension. There's always next year tho! 

Probably, in the middle of trying to figure out the case capacity and proper powder to run it through the powley computer.

Okay, back and ran the 7mm Kurzer in the Powley Computer using rough estimates. The Kurzer has the advantage in case capacity thanks to the case just being a cut-down 7mm Mauser. If anyone has any qualms about this or advice, please add in.

Edit

That's ballistically going to be slightly less than the British 7mm Mk 1z (aka .280 British) of the ill-fated British EM-1 and EM-2.  Since you have more case taper and a shallower shoulder your loosing some volume.

A 160 grain projectile will eat up most of your available case volume, best scale it back to about 135 to 140 gr.  The .280 British was able to get t about 2450-2500 fps with a 140 gr BT, a 160 gr bullet would be really sluggish...

Oh, and the Germans did experiment with 7mm for the MP43, 8mm was chosen for simplicity of production (no new barrel blanks required).

EDIT: I think your case capacity is a little optimistic.  By my calculations your going to have 33 to 38 grains minus whatever the bullet displaces.

I agree with you on the optimistic factor, although regular loading grains are always lower than the case capacity. The 160 grain projectile was for the original 7mm Mauser, I had that cut down to 110 grains, and using 3031 powder via the charts. The 7mm/.284 does enjoy superb BC, although it won't get to 6mm-6.5mm ranges.

Now here's the part that shocked me, I started running it through a ballistics chart compared to the .223 Remington. I doubled and triple checked to make sure nothing was off. I don't know if I'm hallucinating or not.

Your not, the bullet is  twice the weight and nearly the same BC.  You are getting about exactly what the British were getting back in 1949.

Try it with a 130 grain Sierra Matchking going 2450 fps....

It's quite respectable.

Huh, interesting...

As to the 130 grain Sierra Matchking, I'm trying to avoid high-quality bullet selection. I'm trying to make this cartridge as a "Standard Issue" which would be given to military grunts to shoot with.

I would suggest lengthening the case about 0.90", pushing the shoulder forward about .185", and shortening the neck as required.

You'll get the volume you're after.

The shape determines the BC, you can make the same shaped bullets in any quality you want from crap to match quality...

Sierra .308" 155 grain Matchkings are almost the exact same shape as M80 Ball, and track almost the exact same trajectory for the velocity.