I bought a box of this ammo today at the gun show ($14.50/50, not a bad price!) I decided to pull one apart to see the guts of the cartridge. First thing though, I took some measurements:
OAL - 2.245"
Bullet OAL - .985"
Empty case OAL - 1.765"
Loaded cartridge weight - 194.3 grains (avg of 5)
Empty primed case - 96.1 grains
Bullet weight - 75.3 grains
Powder weight - 23.0 grains
It took 6 very solid hits on concrete with my kinetic bullet puller to release the bullet. I can't really tell if the bullet has a cannelure or not, but there is a very definite ring all the way around the bullet where the case mouth was. I don't know if this is the cannelure, or just a ring caused by a very tight crimp on the bullet.
The powder looks to be ball of some sort, definitely not stick. The published velocity of this round is 2750, so I'm not sure which ball powder will generate that velocity with 23.0 grains. It is possible that it isn't even an "off the shelf" powder.
Here is a PMC 55 grain FMJ for comparison: (the PMC had 25.2 grains of ball powder.)
I noted something interesting about the PMC round. The shank of the bullet had some black, sticky stuff on it, and it took a good 15 solid whacks to get the bullet out of the case. It almost seems like it is sealed. It didn't wipe off very easily until I put some degreaser on my rag.
I hope to get to the range soon to do some chrono and accuracy work with my LMT M4 16" upper (1/7.) I should probably run it through my 20" HBAR as well (but it has a lot of rounds down the tube......)