22cal is a long list as the gun is not picky. FX 16,18,25, plus FX Hybrids, JSB Knockouts in .217 and the MKII's in .216. Also, Baracuda 18's, 21's in match grade, NSA 20.3, 24.8 and 17.5's but could only shoot them with the Pellet transfer port as they kept getting hung in the Slug transfer port side as they are short. Pellets shooting anywhere from 860 to 900 except for the MRD's shooting up to 935fps. I shot all slugs over 900fps up to 990fps. I usually start at 925-950 at 50 yards to see how the accuracy is before going up or down. Also, JSB 33.95 Beast shoot well at 50. I hear they are not as good at 100 comparted to the 25.39's but didn't check. H&N 23 and 25 grain slugs did well in the .217 version, but not the 21 grains. The Standard Superior liner does well with slugs 25 grains and below and still shoots pellets well.