Does your Umarex Beretta M92 FS leak out the front or rear?  These are the most likely seals to fail.  After a lot of experimenting "and wasted Co2" we have found these a superior upgrade to the original seals. If you are comfortable servicing your own gun this can save you time and money.  There are online guides to assist you.  I will also include two of the tiny detent balls the safety and slide release uses that are easily lost.  ATTENTION this is for the pellet version of this gun and NOT the BB.  We can send internationally for $1 more.  GOOD LUCK!!