Working up a reduced 223 "Hornet" load that will cycle a 24" barreled AR-15. I've been trolling the internet looking for something on this and thought I'd post up my results. All powder drops listed here are below listed starting charges. Hodgdon indicates minimum safe load is 60% of listed max. I started at the upper end and worked down watching for projectiles stuck in the bore.
223 Lake City Brass
BR4 primer
H4895
50 gr Sierra Blitz - old style, not Blitzking.
17.0 gr 2,060 fps. Cycles but bolt doesn't lock fully back on empty.
18.0 gr 2,136 fps. Cycles but bolt doesn't lock fully back on empty.
19.0 gr 2,204 fps. Cycles and locks open on empty mag.
19.5 gr not chronographed. Groups better than 19.0 gr loading. 1-1/2" @ 100 yards. Shoots 2" low, centered.
20.0 gr 2,417 fps.
22.0 gr 2,708 fps. Same point of impact as standard loadings.
Swapped out the 50 gr Sierra Blitz for a 55 gr Sierra HP #1390 Gameking. Shoots 2" low, centered with 19.5 gr.
