I have computed some ballistics just a rough estimate.
If your gun is of standard barrel length for a 1-66 twist in 50 cal
using pyrodex 2f powder with 70 volumetric grain load as you stated.
With a weight of 177 grains for a round ball made of Pure Lead with a diameter of .490". It should look like this.
Yards / Velocity / Energy FT/LBS / ETA In Seconds
25 /1204.82 /570 / 0.056
50 /1026.51 /414 / 0.124
75 /922.23 / 334 / 0.201
100 /845.67 / 281 / 0.286
Zero at 75 yards gives you a trajectory like this.
25 yards 1.67 inches high. 50 yards 1.84 inches high. 75 dead on. 100 yards 4.28 inches low.
I would limit my shots in this case to 75 yards max. Yes upping the powder charge will give you more FT/LBS at any given yardage but not much good if not accurate like you stated & why you stuck with 70g charge. Good charge for the slower 1-66 twist you have.
Keep in mind. The Round ball weight will be effected by the alloy used to make it it also will have different ballistics and trajectory. A different ball diameter also effect this. Here are weights by alloy for a .490" ball. A weight of 177 grains for a round ball made of Pure Lead with a diameter of .490".
A weight of 170 grains for a round ball made of 1-10 Alloy with a diameter of .490".
A weight of 171 grains for a round ball made of Wheel Weight with a diameter of .490".
A weight of 163 grains for a round ball made of with a diameter of .490". Linotype
A round ball is unique among projectiles in that its ballistic characteristics are solely dependant upon its diameter (unless it's made of something other than lead) Also, a lead ball has a very poor sectional density (SD), and consequently poor penetration due to so much expansion but out to 75 yards I think your ok might have to track if you hit bone such as shoulder at 75 yards. Newer jacketed bullets have much higher SD leading to very good penetration most of the time passing right through the animal hints the need for a poly tip to aid in expansion on impact. Solid copper would be hardest to expand but very good penetration. Jacketed lead core bullets less SD good penetration more expansion on impact due to lead core still need a poly tip to expand tho.
Conclusion You can't kill what you can't penetrate & at longer ranges like 75 yards you will need a minimum amount of energy ft/lbs behind the ball to penetrate the hide & rib cage. Also enough SD left to do so due to lead expanding so much with such poor SD it even expands in flight. You will have met that requirement at 75 yards further then that you will just wound him or make him really mad. Now comparing this to a bow is very different broadheads have razor sharp cutting edges unlike bullets or round balls. That's why they can kill with under 100 FT/LBS of energy. Hope this answered your question MWP
Last edited by midwestprowler; 12-03-2012 at 08:59 PM.