Finally decided to start reloading .223, up to this point I have only done the larger calibers. Did these straight out of the reloading manual. Brand new can IMR 4320 powder, Hornaday 55 gr bullet, small rifle magnum primers all per the book. Today when shooting the first test samples, the first round was nothing more than the primer pop. I took a peek down the barrel and there was a lot of unburned powder grains. The 2nd and 3rd rounds had similar result, bullets dropped short of 100 yards by about a foot, leaving the rifle on the bench and looking down the barrel, it was 1/2 full of unburned powder. Gun functioned as normal with a different round. What am I missing? Powder wasn't wet, opened with the factory seal and put right into the rounds we loaded. Any ideas or pointers?