For comparison sake my 30/06 Mauser where's a 27.25 inch #5.5 contur ss Hart 1/10 twist bbl ,with a max reload of H4350 & 155 Sierra Palma match king it Cronographed 3070 fps over my friends 100 dollar crono ,175 SMK did 2910 fps,168 SMK did 2965 . by my thinking the op should have gotten 3100 /3150 fps... my heavy Mark Chanlynn 308,,,,,,, 28 inch 1/10 twist BBL l pushed a moly coated Speer TNT 125 to 35oo fps backed it dwn 1 grn and it did 3450fps &.318 at 100 yds. but im still not seeing how the op did 3400 fps with similar case capacity so I looked them up ,source Barnes #2 reloading manual, 308 ,W-W-C 53.53 case capacity of water , .284 w-w-c 64.59 cc of water ,and 30/06 w-w-c 68.01cc of water . Somethings just not right... OP any suggestions ???