Range Report Actual/Observed BC for 123 Amax

[ddavis]

My observed numbers for the .264 123 grain A-max seem to be lower than the advertised G1 BC of .510. In fact, if I play with the numbers the BC seems to be closer to .480. I have Litz's book, but the 123 Amax is not included. Ballistics programs predict 10.0 mils @ 1000 and it took me 10.8 this past weekend. Of course there could be other things at play, but even at 500 yards when verifying my come ups I see the same trend. Thoughts?

 

[Lowlight]

Re: Actual/Observed BC for 123 Amax

How do you know your scope is right ?

Lots of things come into play, MV, Rifle, etc...

It is what it is, and if everything matches up with .480 then that is the right number.

 

[ddavis]

Re: Actual/Observed BC for 123 Amax

I realize that it is possibly the scope or several other factors. It would be difficult to account for all factors, though I will continue to try to do just that to find out definitively for myself. I still need to check my scope to make sure everything is correct. May do that this week. Not looking for the easy way out, as I will continue to try and get my own values, just seeing if others have made the same observations.

Regards,
-Dan

 

[bohem]

Re: Actual/Observed BC for 123 Amax

Across several rifle/scope combinations and lots of different atmospheric data I've seen the average BC a lot closer to 0.49 than 0.51; I've had the bullet out as far as 1200yd.

Like Frank said, you need to verify everything is right (a good way to do this would be to shoot some "known BC" bullets and work from there) but my experience with the 123 Amax is that this is a reasonable notation you've come up with.

 

[ddavis]

Re: Actual/Observed BC for 123 Amax

Thank you sir. That's what I was looking for. I'm going to measure out some targets and check my click values of my scope and go out and do some more testing when I can get back to a range >100 yards in the next month or so.