If you're testing whether it works or not you can dry fire a little bit but then you have no indication of how BB's feed (ie. whether or not X brand of BB's jam in it or not) but then again if you're buying high quality BB's it shouldn't be a problem.
Just testing that it cycles and that no weird/worrying sounds are being made by the gears or motor a couple dry fire shots won't hurt it. Just don't excessively dry fire.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE