View Full Version : Calculating bullet drop using Software.

01-22-2010, 03:39 PM
I have had some head scratching going on with different results from different programs. I had become comfortable with JBM but went away from it for a while and see new changes and am getting squirrely results now.

Can some one tell me what I should have for bullet drop out to 600 yds at 100 yd increments if: preferably using JBM trajectory

Velocity at 10' is 3110
Bullet is 69 gr HPBT Cutom Competitive Nosler
b.c. .305 (g1) per JBM
zero 100
900 ft asl
29.1 borometer
site height 1.637
Target is flat no incline, no wind,

I hope I can use this number to see if I can get the same results. Makes me crazy:confused: at 600 yd I get 86" drop. Does that seem right?

What really makes me unsure of what happening is that using a 77 gr HPBT match shows a drops of 77" at the same velocity.

01-23-2010, 10:03 AM

I posted and then deleted thinking someone may run the tables for you and then respond. It looks like there are no takers.

Anyway, what I said was that those numbers are probably OK. A bullet with a .305 BC at 3110 fps is not a very good 600 yard combination. 86" of drop is 14 MOA. Most good 600 yd and 1000 yd loads will show around 10 to 12 MOA at 600 yards.

IOW, I don't think JBM is lying to you. You can always shoot a few to check the numbers, something that you should always do, regardless.