Advanced Marksmanship POI testing

[calshipbuilder]

I'm getting ~4 moa of vertical dispersion when shooting long range with a hot barrel (10+ round strings). POI shift is not consistent; it will be high, low, or right back to center. Most of the time its high. I've eliminated the scope and ammo as potential causes through prior tests. At 600 yards, its not bad, even over three 20rd strings, but when I shot a 800, 900, 1000 match, it became increasingly worse as I went out, I also see this on steel with unexplained fliers, and when I correct off them I end up way under the target.

I think its either mirage off the barrel or the barrel shifting as it heats up. (Krieger M24 26" 308 win)

I plan on shooting a 30 round string at 100 while eliminating barrel mirage and seeing what that looks like. Anyone have a better idea?

And yes, it could always be my poor position, trigger control, ect., but I've put enough rounds through this rifle to call my misses, and the unexplainable vertical shift is very consistently an issue.

Thanks!

 

[CharlieNC]

Could be velocity variability. Do you have chrono data?

 

[calshipbuilder]

Its not, ammo is not the issue, all shooting with this rifle is either M118 LR '09 (2712 fps, SD 10) or 175 Gold Medal match, (2683 fps. SD 12) I've got ~50 rounds of M118 over magnetospeeds and labradars and ~30 of GMM over 2 magnetospeeds. About 1000 rounds of each on this barrel, same issue. I've also tested zero holding and tracking on the nightforce ATACR F1 and had it re-verified by NF.