230 Berger Hybrid B/C's

[Tumbleweed]

Hi all.
So I would like to get some feedback on your experiences with the working ballistic coefficient numbers for the 230 Hybrid Target bullet. What B/C's have you found to work in your programs producing matching drop data? The original published B/C's for the 230 were .380 G7 and .743 G1. As we all know those were updated a while back to be .368 G7 and .717 G1.
I recently used a friend's Magnetospeed for fun and discovered a BIG difference between what my numbers suggest I'm running velocity wise and what his chrono says. We're talking 80fps difference. I have been successfully using the .368 G7 B/C in my Shooter program to 2100 yards and it was spot on. I run a drop verified 3,210fps out of a 9 twist barrel.

So I proceed to mount the riflescope in a fixture to run a tracking test on it to see whether my data was skewed by over/undertracking. I was able to confirm that the scope tracks perfectly to 25 MOA and by 30-40 MOA is barely overtracking by .25MOA.
At this point all that's left to skew numbers making the program velocity appear incorrect is ballistic coefficient. I ran numbers between the original .380G7 and the updated .368G7 with the same input velocity. At 1110 yards this would only amount to .4 MOA difference. If I adjust the velocity in the program to make the higher B/C match known drop on target my muzzle velocity would still be within 25fps of what I'm running in my program now.

So, my conclusion at this point is that my friend's Magnetospeed is having issues or the 230's B/C is running much higher than expected in my rifle.
Not sweating this in the least as my numbers work extremely well and are proven with drops. This just has me slightly puzzled.
Thanks!
Jesse

 

[learning]

I suppose a 32 inch barrel and h50 may get you some pretty good velocity. It seems kind of high based off the guy one thread down with a 26" barrel with a bulging shank and he got 3129. What about scope height.

 

[Tumbleweed]

I suppose a 32 inch barrel and h50 may get you some pretty good velocity. It seems kind of high based off the guy one thread down with a 26" barrel with a bulging shank and he got 3129. What about scope height.

Scope height is accounted for ( 1.9") in my Shooter program along with everything else I can account for

 

[learning]

Your velocity looks like improved lapua case velocity. I don't believe chronos are a bible by any means, however that seems pretty fast in an ultra mag. This is an ultra mag right?

 

[learning]

If your 2100 yards is google earth measured like in your other thread than I would look to that as your culprit.

 

[Tumbleweed]

If your 2100 yards is google earth measured like in your other thread than I would look to that as your culprit.

My drop data really isn't based off of the 2100 yard target data. I actually walked it out on paper to 1,110 yards to get a great start on accurate drop data. On random targets in the mountains the data has tracked very accurately at 1475, 1800 and 2100 yards as well.

 

[Tumbleweed]

Your velocity looks like improved lapua case velocity. I don't believe chronos are a bible by any means, however that seems pretty fast in an ultra mag. This is an ultra mag right?

Yes, RUM. It has a 32" barrel with a very long, match throat in it.