What do you get when you cross the American made 5.56x45 with the Ruskie 7.62x39?
Answer: The 30 Apache or 30-223Rem
The 123gr bullet of the Russian cartridge with the case of the American cartridge.
24gr of H335 and 2100fps 10 feet from the muzzle of the rifle means the ballistics of the Russian and the plentiful American cartridge.
Pluses - standard AR15 bolts and magazines can be used along with reforming 5.56 cases which are very plentiful.
Minuses - slightly slower than the Russian parent cartridge and the brass necks of the reformed 5.56 cartridges are thinner than the original which causes case necks to crack on 3rd reloads if not annealed when first reforming. Also you have to pay attention when you reform the shoulder of the new cartridge as it's pretty scant but functional!
To get this cartridge onto an AR15 rifle, I re-chambered a 300BLK barrel (cute cartridge but too much like a pistol cartridge) and added an H3 buffer to replace the lighter carbine buffer and a carbine-length pigtail gastube to the extend the original gas tube from the pistol length port on the barrel.
For my lead-casting friends - it's loaded with a Lyman 311359 mold which with my alloy drops out at 120gr and after lubing and gaschecking weighs at 123gr which matches the Russian AK47 cartridge exactly.
For my non-AR15 shooting friends...bear with me...its been almost a 4-year exodus getting this wildcat working on my own in between retirement from the Army, neck surgery, recovery and starting my current job at the American Legion.
For my friends who enjoy odd calibers, consider this as a either a very hot 32-20 or a super-hot 300 Sherwood!