Mounted a Leupold mark 5 before my hunting trip. Was able to shoot 15-20 rounds before the trip. Zeroing it at 100 and taking it out to 600 yards to verify velocities etc. everything was great. Hunted two weeks in Colorado and missed a mule deer at 500 yards 3 shots. Come back to Texas to check things out and my zero shifted 2 1/4”-2 1/2” low at 100 yards. Checked screws on the ARC rings, kelbly scope base, and screws on the Xlr chassis. Everything was good. Running a dead air nomad 30 with area 419 muzzle adapter with splendid results. Does this sound like a scope issue to you guys?