My Sierra book shows at 16.5 grains of 4227 and a COL of 2.105" you'll get 1850 fps and 1178 ft/lbs. I e-mailed Sierra, they said that would be a good deer round. This was 5 rounds at 50 yards.
Not to thread jack but... Have you or anyone else ever experimented with varying the COAL or CBTO to see what affect it has on accuracy? I loaded up a box (50) of Hornady 125 OTFB over 18.5 g Lil-Gun yesterday and varied the COAL from book to max of 2.260 (max for mag length). I've read if you get it closer to the lands, for less jump, accuracy will improve. Haven't tried them yet. That's today if I get time.
We've been quite impressed how versatile and forgiving the 300BO round it.