I got my Lee312-160-2r mold in the mail today for my 300 Blackout. I cast up a handful of bullets, powder coated them, and loaded ten of them to make sure they were going to function.
I loaded them with 16 grains of Lil Gun with an OAL of 2.018 inches. I have the cases trimmed to 1.355" and that puts the last lube groove even with the end of the case. I put a mild crimp on the cases to help prevent bullet setback.
I didn't put them on paper, but I did confirm that they were able to at least hit an 8" steel plate at 50 yards. I was shooting offhand with a red dot.
Ejection was strong and to the 4 o'clock direction, primers are not flat, and the cases were fire formed to the chamber. Cases were made from once fired 223/556 cases.