My brother recently bought a traditions pa pellet. I was attemting to sight it in yesterday and this morning and it was grouping good at 25 yds but was consistently hitting low. Maxed out moving the rear sight up and Tried several different powder charges/projectile combos and it was hitting low with all of them! Im talking like 3-4" low at 25yds. Im a relatively experienced flintlock shooter and open sight shooter in general, so i dont believe its me flinching etc. Sight picture was consistent on all shots. I even got my PA pellet out and tried my hunting load with it and it was dead on, tried it with his and low again! His was bought used but barrel is clean etc. Sights look like original fiber optics. Any ideas on causes/fixes to this? Maybe front sight or rear height off?? Im flustered!!