more help please

[bruno]

well i finally made it to the range last week, and with my reloads. i was trying to work up a load for my 270. i started at 46.6 gr of win760 and loaded 4 each up to 52.7 in .5 gr increments. every charge was weighed, and all cases were full length once fired brass from the two boxes of factory ammo.(win). im wondering what the expected variation in velocity should be, as mine was about 40 fps max. some of these four shot groups had 2 the same and 2 lower. as expected these ended up in different places on the taget, close but still different. I then did it all over again with brand new resized remington cases, all from the same bag. still had variations of about 40 fps in the strings. none of the loads were crimped. i was using 140 gr hornady SPBT with federal large rifle primers. for the record, the second time i think i forgot to dry the flash holes on three, because i had 2 hang fires and 1 miss fire. both firsts for me. was able to get 2940 fps out of 22" tube