Changing the advertised B.C. to fit???

[Santiam338]

338 WM,26 inch barrel,200 gr Accubond with a advertised BC of 414..

Using the shooter app to get my 800 yard drop to fall in right I had to go up to a ridiculous FPS of 3225...I know I am not near that fast so back to the drawing board...

To make a long story short I ended up using a B.C. of .490 and things fell in just about perfect to what I was seeing on paper at 400,600 and 800 yards...

Does this seem out of the ordinary to raise the B.C. that much to match things up or do I still need to investigate further..

I am going back up in a few days to play some more and do more math..

Thanks.

 

[tim_w]

I would say yes something is not quite right. IIRC Litz had lower than the Nosler published numbers for G1 for the accubonds not higher. I would think ideally using the G7 BC. Still I would not expect that.

What program are you using ? Accounting for elevation, pressure, temp? What chrono are you using? My gut would that that changes in the exterior conditions not the bullets BC might be where the answer lays if you are having to go up over the published BC.

 

[Santiam338]

Using Shooters and with the right altitude,pressure and temperature..It has always been spot on with my other rifles and Berger bullets...

The Chrono was actually reading about 70 fps faster than I was expecting..After allowing for the revised speed and rechecking my 100 yard zero I was still high at 800 yards by 2 minutes..

I may switch scopes and see if I get the same results...

Everything does work with the 490 B.C. If the math works its all good right?..LOL

Thanks