Calculate your own BC

Wrote an article that was published in the NMLRA Muzzle Blast magazine.
I’ve read some use 2 chronographs, 1 Muzzle, 1 at 100 to do such. I do it a little differently with my chronograph (just 1).
1) sight you ML in at 100yds.
2) without changing anything on your scope, shoot a group at 200yds. Note: were I aimed on the 200yd Red Bull Target- 12 o’clock.
3) Measure the actual distance the bullet dropped at 200 with a tape measure. With this load 18” exactly.
4) Input your MV, bullet weight with a 100yd Zero into any Ballistic Program (I use Hornady, because the inputs are basic). Keep adjusting your BC until the drop at 200yds matches your actual drop on your 200 yd target - in this case 18”.
That’s it.

Since I have a 300 yard range available, I took my sons 40 back out to the range and shot 1 shot from a cold, clean bore. The Hornady Ballistic Chart showed the bullet will drop 18.6moa at 300 with a 100yd zero. I adjusted my sons rifle scope elevation to 18.75moa and with a slight right-to-left breeze - I aimed center X, and squeezed off the shot.







300yd

Good stuff Rick.

This makes things alot easier! Thanks for sharing.

I do something similar to calculate my muzzle velocity without a chrono to input into a ballistic program with my CF rifles (I need to just buy a chrono! lol).
Only works if you can find the bullet BC online. I input all info into the ballistic program except the MV. (I have a small GPS that tells me the temp, elevation, and barometric pressure). With a 100 yard zero, I then shoot at 300, measure the drop, and then play with the MV in the ballistic program until it matches my actual.

Renegadehunter said:

..... (I need to just buy a chrono! lol).
Only works if you can find the bullet BC online. .....

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Yes, you need to buy one if you enjoy shooting.
As for BC - unfortunately, there is BS in BC with a lot of mfg ML bullets.. Some better than others.
Since I make my own bullets, I had to come up with something.
Good luck.

This is 54 cal Idaho. I can't get to the range like I should, it's just too cold. Anyway, what I would like to know is the MV of a 54 cal. shooting a.230 gr .530 rb with 105 gr peroxide powder. The muzzleloader is aTC Renegade, with a 1/24" twist and a 28" barrel.

54 cal Idaho said:

This is 54 cal Idaho. I can't get to the range like I should, it's just too cold. Anyway, what I would like to know is the MV of a 54 cal. shooting a.230 gr .530 rb with 105 gr peroxide powder. The muzzleloader is aTC Renegade, with a 1/24" twist and a 28" barrel.

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Are you sure about that twist? Should normally be something more like 1:48” twist. Or even slower.

michiganmuzzy said:

Are you sure about that twist? Should normally be something more like 1:48” twist. Or even slower.

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yes, you are right it is 1:48 twist.

I thought maybe you had one of those ultra rare unicorn drop-in barrels that GM made for TC.

Never used that peroxide powder?

I use a LabRadar as well for all my rifles and it sure makes life easy.