The last two rounds I chronographed 11' from the muzzle measured:
That same day I measured two rounds at 290 yds from the muzzle @:
Atmospheric conditions at the time were:
Station Pressure = 29.79 inHg
Temp = 56 F
The BC determined for these Atm conditions from LoadBase 2.0 was 0.660.
So I get pretty decent ES and SD. Not always as low as these data, but typically less than 20 ES and 10 SD.
On the increased muzzle velocity I'm seeing, I partly attribute it to the treatment of my bore with a product called Gun Juice. See this thread for further information: gun juice what is it?
If you don't want to mess with the Gun Juice, this load still shot very well out of my rifle prior to treatment with Gun Juice. But after treatment of the bore with Gun Juice, I now see approximately 45 fps increased Muzzle Velocity.
I have also chronographed velocity at 987 yds. Scary as heck shooting over my chronos at that distance. Based on the collected downrange velocities, I now use a BC of 0.684, and Drag Coefficient of 0.460 in my LoadBase 2.0 ballistic software under specified Atmospheric Conditions of Station Pressure 29.24 in Hg; 21.5F; 91%RH; and I'm pretty much right on the money.
Oh, and my chrono information is of reliably high quality. I shoot over a dual chronograph setup. One Oehler 33 with a 6' skyscreen spacing, and on Pact PC2 with a 4'5" skyscreen spacing, so I have two velocities collected for each shot, and if one of the two chrono's throws a bad velocity, I see it with an unusual spread between the two collected readings. So the velocities are not BS.
My personal belief is that the best loads are rifle specific, but you might try IMR 7828 if you're not happy with the load you're working with.
Oh yeah, accuracy out of my ~8.5 lb custom rifle
is in the neighborhood of ~ 0.3 moa - 0.5 moa, depending on which side of the bed I roll out of.
I think you've got it all now. Good luck and good shooting.