I just had the the chance to run my Cooper through the chrony. The rifle is a model 52, 24" barrel, chambered in 6.5x284 Norma. I have shot this rig out to 1,000yds. The one thing I now know, there is quite the difference from 500yds to 1,000. Anyway, the load I chronograph-ed was 140grn Berger vld's, 51grns 4831sc and a base to ogive of 2.380, which is approximately .01 off the lands. I was hoping the fps would be around 2,850. The five shots were, 2,996 / 2,926/ 2,969/ 2,965/ 2,943, for an average of 2,959. From what I've read, the sweet spot for this cartridge is 2,950, for what it's worth, that also seems to hold true for this rifle as well. Enjoy the outdoors!
Not sure what's up, we also chronographed a savage with a similar load, 50 grns of 4831sc, also with the vld's. ended up in the low 28's with that configuration. I never would have thought it would have been that high, but we used the same chronograph for both rifles.
Are your field data drops at distance, 500 yards or further, matching what your ballistic app is showing they should be for that velocity and distance? It is hard to see errors in velocity or BC up close but at the further distances you will much easier begin to see if your BC and velocity numbers are correct or not.
I actually did things a bit ass backwards. I got things on track at 500yds, which was 8.5 MOA's up, then played with the velocities on the BC to where 8.5 moa's was right for 500yds, and that was 2950fps. Out to 1,000yds things seemed to drop off a bit more, a full 21 more Moa's to hit steel. So I guess things are working out fairly close between the chronograph and the BC. I try learn something new every time I shoot, and I need to shoot a lot more.
Just be sure you are not overlooking a couple things.
1. Make sure you know your true turret adjustments per click. If those are different than what your app inputs, most likely .25 MOA, then your ballistic program will compensate somewhere to make it up and the way you are doing things it would have to change velocity to make things match.
2. Make sure you zero distance is exact. This will mess things up downrange as well.
3. Make sure you have your scope height correct. A small thing but it can mess with numbers.
Atmospheric conditions and shooting skills aside, you are now left with only velocity and BC as factors that can affect POI. I personally always adjust velocity first and only mess with BC's if nothing else will work.
That does help, and I believe I had everything you mentioned in 1,2,3 of your feedback. I my response I mentioned BC, (as in ballistic calculator) not to get you confused with Ballistic coefficient. I do have the bullet bc's both g1 and g7. Thanks for the input and feedback. Everything helps.