264 USA (6.5x48mm)

I have an unusual request you may or may not be able to help with.

I would like to calculate likely velocity, chamber pressure, and suitable powders for the 264 USA. As you may know this is a developmental military cartridge for possible adoption by US armed forces.

OCL is 2.6 inches. Cartridge base is identical to 762x39 case head. Body taper and shoulder taper are modest for use in automatic rifles and light machineguns. I can supply case dimensions if required. The International Cartridge Collectors association says it has a 42 grain H20 capacity. Bullets used in development are the 108 grain Scenar open tip match bullets.

I am curious about this bullet because the claimed velocities for it are so high in very short barrels. According to the RFP:

2,875 ft/s for the 108 grain from a 16.7″ barrel, and 2,650 fps from an 11.5 inch barrel. 2,750 fps from 11.5 inch hoped for. 14.5 inch will also be tested. .

This is intermediate in size between a Grendal and Creedmoor!

It just sounds very ambitious to me with what is likely to be a 35-37 grain useful powder charge.

thanks for any comments.

Andy

Woops. Looks like I should have posted in Quickload thread.

Is it possible for a moderator to move it?

Sounds pretty interesting Andy. I don’t think I’ve got that cartridge in my QL database.