Author Topic: Calculating BC (Read 425 times)

Dusty Miller · « **on:** November 27, 2004, 08:46:43 PM »

I guess this is as good enough place to post this as any other! Does anybody know how to calculate the BC of a bullet by taking measurements and plugging them into a formula? I'd like to know the BC of my WFN and WLN bullets that drop from my LBT molds.

New Hampshire · « **Reply #1 on:** November 28, 2004, 12:20:31 AM »

I gues you could start here:
http://www.handloads.com/calc/index.html
Brian M.

MtJerry · « **Reply #2 on:** November 28, 2004, 08:33:51 AM »

Dusty,

I have recently started shooting cast bullets in my 45-70.

I have been wondering the SAME THING! Thank you for asking the question!

New Hampshire,

THANK YOU for the answer! That site is now bookmarked.

Duffy · « **Reply #3 on:** November 28, 2004, 01:30:54 PM »

I wondered the same thing when I got my 320 LFN 44 mould from Veral. He hadn't tested them and didn't know. I set up two chrono's and fired twelve rounds and averaged them out, them compared the data to the charts and a ballistic program. What I came up with was around .233 BC. In actual shooting though it seems to be better than that. You can get pretty close by comparing shapes to bullets with known BC also.

Iowegan · « **Reply #4 on:** November 28, 2004, 02:10:25 PM »

I've been using Oehler's Ballistic Explorer software for years. It allows you to plug in variables and compute actual BC. You need a chronograph to measure muzzle velocity and down range velocity (100 yds is best). Plug both velocities in and it will give you the BC.

My data shows a .180 BC for your bullet. There aren't any 44s that go much over .200 so your estimate might be a little high.

Donna · « **Reply #5 on:** November 28, 2004, 11:12:30 PM »

You could also give my web site a look see, go to the "trajectory part 3" for BC. this will give you a good knowledge base for understanding BC's and the other trajectory pages will give you a wealth of information on trajectories.
My site is www.aeroballisticsonline.com

Donna

Duffy · « **Reply #6 on:** November 29, 2004, 06:25:04 AM »

Iowegan,
Just for giggles plug these figures into your BC program and see what you come up with.

Bullet grain wt. 317
Muzzle vel. Av. 1422
100 yard vel Av. 1213
Temp 68 deg
Alt. 1700

Iowegan · « **Reply #7 on:** November 29, 2004, 08:46:58 AM »

Wow! BC came out to .2245. That's pretty impressive!

Duffy · « **Reply #8 on:** November 29, 2004, 09:33:00 AM »

See, I wouldn't lie to ya!

Lone Star · « **Reply #9 on:** November 29, 2004, 02:57:43 PM »

Several popular jacketed .429" bullets have BCs over 0.20:
Hornady 300xtp - .245
Speer 300mag - .213
Sierra 300 SP - .230 to .250
Heavier cast bullets could have even higher BCs depending on their form factors.