Hi TigerTim,
My Huntsman CLassic XL was purchased in June of this year; so it's the latest Classic model but without the Reagals Titanium Valve set up new stock ect. My Classic is set at 30lbs & and is pushing around 875ft per second with Exact Diablo 15.89grain pellets; variation over the whole fill is not worth worrying about when sighting in at 40 or 45yards it doesn't show up. My Classic XL came with a choice of 30lb & 35shots or 40lbs & 20shots. When you choose 30ft lbs you have a large range of pellets to choose from I like most people chose around 16grain but you can drop down to 14.5grain but a bit light in my opinion. Then again other people are using air arms 18grain pellets sucessfully; when I tried bisley mags 21.4grain my rifle didn't like them group wise & they were more of a lob in the air. Basically 40ft lbs rifles reduce pellet choice your looking at Bisley Mags or Weirauch Mags; as the amount of air going up the skirt of a 16grain pellet will probably blow it causing loss of accuracy. Also I've got Daystates Silencer on my Classic XL 30lbs & that makes considerably more noise than std sub 12ft lbs so heaven nows how much noise a 40ft lbs will make. At 50 yards with Exact Diablo pellets; the pellet goes through a rabbits head & also a pigeons body with heart & lung shot. I honestly don't believe there's any advantage in using 40lbs. The Regals internals have been tweaked & should produce a few more shots than my Classic XL in all honestly I'd stick to 30lbs. If you phone Daystate they will set the rifle at what you want I asked for 900ft per second which they set rifle at without a silencer fitted; but with silencer it's dropped to 875ft per second. Phil Price from A/World recomends 900-925ft with 16grain pellet & you won't go wrong.
Feel free to PM me if any more questions
Regards,
Steve Harris.