Thread: ballistic calculator's can be wrong

Originally Posted by Hbwanderer

@grandpamac, the load was 44grns of Varget pushing 150grn Winchester powerpoints,Used those because i have heaps of them, Dont get me wrong i was happy with the grouping (2inches @50yrds) 50 yrds will be a long shot for the bush i hunt.
My whole point for the thread was online calculators and real world results sometimes can be complete opposites, and yes the rifle is new to me but was in a sad state when i came across it,it had had a hard life,Made circa 1960, the throat is more than likely worn as i had to cut 2 inches of the barrel (muzzle end) before i found any decernable rifling,

Ballistic calculators make a lot of assumptions and can be well wide of the mark. I prefer to use tested data together with a chronograph for load development. One thing that I have noticed with data for the .303 is that it varies widely with pressure tested data giving considerably higher than that from Lee Enfields. I often wondered if the difference came from throat erosion. Measuring the crush length for 174 grain RN was around 6mm longer on a used but in good condition barrel than two near new barrels. I still have to chronograph the same load to see how much difference this makes.
GPM.