accubond unexpected trajectory

[BTnerd]

This is really a "medium range hunting" question. I've been working up loads for my 270wsm and settled on 140 accubonds,62/4831 -.005 from touching the lands @ av.vel. 3045. Sighted 2" high at 100, they are 2 1/4"@ 200 and dead on @ 300. I do not know the B.C. of this bullet, I am assuming .500 ( I have a bag of seconds with "B.C. +.500" hand written on the label). These impacts do not correspond to any chart I can find, for ex: to hit dead-on @300 Nosler book has 3.3/4.0 for 100/200. At 565yds. I'm a little closer to expected with a drop of 35". Is it common for the charts to be this far off or is something else going on? As a control I shot my 30-338 w/165 bal. tips which shoots nice consistant groups exactly where the Nosler charts puts the 165"s out to 500yds.

 

[4ked Horn]

Boy that is a good one. The closest I could get was 2.8, 3.4 and 0 at 100, 200 and 300. And that was with an elevation of 15000 feet, 100 deg, 0 humidity and a BC of .99

But your published BC is .496

 

[jb1000br]

how level/bumpy is the terrain you shot over?

any wind? direction?

JB

 

[BTnerd]

The shooting angle was level, over very broken ground (freshly logged clearcut). I shot groups at all three ranges on two seperate days, one day had a bit of a breeze, the other day was absolutely still. I have shot quite a few bullets/ weights and the accubonds are the only ones that shoot like this.