Brocock XL G6 shot count

Hello all, 

I recently purchased a Brocock XL G6, it is all that I was hoping in all areas but one, shot count. From a 200 bar fill over the chrono, my numbers start at 834 fps and 18 shots later I am at around 500 bar and velocities are in the 634 fps range.
From my pre buying research most people were getting 30 shots from a 200 bar fill.

I was was wondering if other people are having the same experience or if anyone has any suggestions.

Thanks everyone for such a great site.