I bought a new 98 and that was the same. Vicious twisting recoil and it went up in fps so I returned it via the dealer. Hull chopped a bit more off the spring which quietened it a bit but it still gave the mounts a pounding. I replaced the spring with a V-Mach kit (waited ages) and it is much smoother. The original spring was just badly chopped at the end and I suspect the pointy bit was digging in to the piston which may be the reason for the twisting recoil.
I haven't used it much as my own internals suffer a bit from the loading cycle :-( Nice though, now in a GinB stock and an old 18-40 PR Leup in a one-piece mount. If I hold it right it hits the aim point :-)
Neil (A N Other one)