None that i know of, just keep it greased up and you will be okay.
Reduces kick substantially to just about nothing, and blast techs even agree that its a great and safe upgrade., my gun's kick was reduced to almost nothing after putting in the kapp thumper., Prolly the best upgrade available ImO. just keep the orings greased up and u will never have any problems
Get one, maybe 2,hehe! Prolly the best aftermarket ram available to date.