Thread: Ballistic truing conundrum

Been playing with loads for 284 & 7SAUM using RL26 with 162 ELDMs and 165 Norma BondStrike. Long story short ended up with some nice tight groups (0.5 - 0.6 moa) and velocities around 3000 fps. Both 284 & SAUM are 22in barrels. The 284 running 3010fps with 162 AMAX & SAUM 2995fps with 162 ELDMs. Interesting and in line with early load dev with different powders, get more speed with the 284, and in this case (RL26) less powder.
Anyhooow, then ran some shots with the SAUM past couple of calm days with 162 ELDMs at 625 yards to validate speeds & drops. Using Hornady bc calculator & Kestrel 5700 both gave me 10moa or there abouts as the come up. But shots were consistently high going over top of 10in gong, and after close inspection of target area & some rough maths estimated that 9 moa should be on the money. So back to shooting position, dialed 9.0 moa come up & confirmed POA and POI were bang on (within 1 inch).
Scope (VX6) is zeroed for 200 yards, 1.3in high at 100.
Never came across a case before where dial up needs to be reduced significantly???
Most times if scopes don’t dial true moa, they dial less - like IPHY or in some cases less. Leupy scopes in my experience tend to dial IPHY or slightly more.
If you follow the truing logic of correcting muzzle velocities to account for drop, then to get 9.0 moa come up you’d expect muzzle velocity of ~3100 fps. No way can I see that out of SAUM & 22in bbl. Similarly can’t imagine BC differences explaining 10% change 10 to 9moa??

Any of you LR experts out there have any thoughts or ideas to explain this mystery?