Adam... lots of variables would change the performance of a gun... i built several monster 2240s and owned some built by others... at 75 degrees with a 14 inch barrel its possible to get a 14.3 grain pellet to do 640 fps... even more with a hotter day... a 10 incher can do low 5s, but that is wasting a ton of Co2. Looking at the pic of the gentlemans gun, it looks like a 8 incher, so look at getting 460 to 480 with 14.3... but she will bark. A LDC may be a good investment. remember that temperature is your friend or foe... too hot, valve lock. too cold no power... so a a warm day will give you a different feel and power than a cold day. Always open your bolt after a shot... wait 15 to 30 seconds before reloading to allow the breach to acclimatize to the outside temp...