They are a great gun, but they are not without their problems.
We bought two of them, a few years apart.
The springs on both had been cut by a chimp with a disc cutter, the spring ends were gouging the gun internals and putting swarf in the grease which was then chewing the seals up.
Not good from a supposed top quality gun.
Fixed by fitting a tuning kit, but when you spend a few hundred on a gun you do not expect to be sorting out the manufacturers problems! If it buzzes like a bee in a tinfoil factory when you fire, the spring is crap!
No buzzing as yet, but we'll keep an ear out