I've been running a lot of ammo through my 600mm Maverick .25 caliber to see what it likes. It shoots great with pretty much any JSB pellets I feed it but unfortunately I can't find them in stock anywhere so I've been looking for alternatives. I haven't had much luck with other pellets so I turned to looking for slugs, I picked up a box of 26.8 grain .249 NSA slugs and 33.5 grain .250 NSA slugs, the .249 have a dished base and the .250 are flat. The .249 weren't great but it loved the .250 slugs, with the power wheel turned to 7 and the reg at 120 bar I was getting 810 FPS and 64 shots per fill. That's with an upgraded 480cc carbon fiber bottle not the aluminum bottle that normally comes with the 600mm barrel though. At 20 meters I was getting dime sized groups, that's the maximum distance I can shoot off my patio table so I'll have to bring it somewhere else to test it further. Here's a set of targets I shot, the two low shots in the upper corner are from dialing the scope in for the heavier pellets. I fired one 16 round magazine at each target.