Re: 308 Win, 208 AMax, RL17
Something that's buggin' the crap out of me here guys and I can use some ideas, input, or anything else to help me make sense of it.
I had a match a week ago today where we were shooting from 100 back to 700 yards. Winds were a little crazy, but from my 6 at a peak of 6mph. Temp was 82 degrees, pressure was 28.46"Hg and RH of 50%. I was shooting the 208 amax's at a chrono'd velocity of 2560avg the thursday before the match when it was 79 degrees. Now at the match I used a G1 BC of .633 as was mentioned in many articles. Well at the match I got the following results;
200 - Scope zeroed out with the group centered .9" over bull, set my zero to 219 in exbal
300 - Called for 2.75moa, dialed 3moa only needed more like 2 after viewing target
400 - Called for 5.75moa, dialed 6moa but only needed ~5moa after viewing target
500 - Called for 9.25moa, I got wise and dialed back 1moa from calculated drop at 8moa after viewing target
600 - Called for 13, dialed 12 pretty much dead on (vertical stringing in group which was a poor rear bag setup)
700 - Called for 17, dialed 16, got the target and the group was still about 7" higher than the aiming point. If I would have dialed 15moa I would have been dead on.
I've been playing around with Exbal to try to get my numbers to match up, they're much better after entering in the high BC of .648 which is the published BC from Hornady. The numbers look much better inside of 600, however it's still calling for much more 16+ MOA elevation correction at 700. If I increase the velocity to 2600fps I get a elevation correction at 700 of 15.5moa. If I do a velocity of 2620 I get a much closer 15.25 but then the other numbers start to get funky. I know these programs are just suppose to get you 'close', however I want to have the numbers put in correctly that will spit out correct information.
Any ideas? I've reviewed all chrono data that I have for this load and it's been sitting comfortably at 2560fps. For it to jump to 2620 suddenly would be quite odd.
Branden