Thread: ballistic calculator's can be wrong

Greetings @Hbwanderer,
If it is a bush gun and 50 metres is a long shot ditch the spitzer and definitely the boat tail projectiles, Try 150 grain round nose projectiles. My experience with 150 grain boat tails is they often don't shoot that well if the throat is worn or long, You don't mention the powder but I have used from 38 to 45 grains of AR2206H with decent results. Stay away from ball powders with reduced loads. Post some more data on the components you have and I can provide some suggestions.
Regards Grandpamac,

Another thought. Is the rifle new to you and if so have you checked all the screws and mounts and the bedding? .308 rifles, even well worn ones, must be the easiest on the planet to get to shoot well.

@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,

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.

Originally Posted by grandpamac

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.

one would think it would have been the opposite, Would be interested in your results, gotta love the ol 303