When a reliable scope loses zero

[antlerz]

Watch out for supressors loosening on the thread, That will move zero in an otherwise solid system

 

[mtnbound]

Reloads from a reloading friend (same batch of 100 rounds)
No contact

Even though it would require a big change in velocity, I would also mention this to your reloading friend and confirm the ammo's velocity. Its a part of the equation.