Sounds suspicious to me. But if you can testfire it and check it out first then by all means go ahead.
As far as upgrades go, don't touch the internals until something breaks. Ideally you'd use it for indoor CQB but if you really need to bring up the speed of the BB's then an M110 spring (you should be aiming for between 350-380 FPS on .20's here) and using .25's or .28's will do the trick to make it a super viable outdoor gun. Just need to lead your shots a bit since the BB will be going even slower if you use .25's or .28's.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE