Thread: 1 load 2 rifles

If you're within SAMMI (factory) specs and published data for your cartridge then all will be fine.
If you're only partial sizing/bumping shoulder or neck sizing, running higher powder charges or longer seating lengths then it may be over pressure in another gun.

I'd be tempted to load up a few rounds going from 10% below up to your current load, check them in his gun. Provided there all safe you can then decide if your current load is accurate enough in his gun or if separate load development is needed.