Hey fellow airgunners! It's been a while since I've been able to do much shooting. I picked up a used Maverick 22 Sniper a few months back, and am finally getting around to setting it up. Initially, I want to shoot lighter slugs in it, so i am sticking with the Superior STX barrel that came with it. I did order and install a slug power kit. I think the 13 gram hammer weight is a bit much, so i have the 11 gram on the way. While waiting, I played with it a bit to see if I could learn the basics of tuning it. I have the first reg at 160 and second at 130. Adjusting the HS tension yielded a max speed of 1018 with 25.39 gr JSB Knockouts and PW set at 7. Lower PW setting yield lower speeds. This is not my final tune, just playing around with it. However, and here is my issue, when i tried to shoot the FX Hybrids, they won't move down the barrel. Tapped the first one back out and tried another. Same result. Pull the trigger, hear the valve pop, then a low hissing as the air bleeds out. Pull the probe back, and the rest of the air escapes. I am attaching a photo of two Hybrids that refused to launch. Checking with my calipers revealed that the .217 Hybrids are one thousandth larger than the .217 Knockouts. i tried two different calipers, which yielded different readings by one thousandth, but both showed the same relative difference in diameter. As shown in the photo, the barrel is peeling some of the lead back. Has anyone else experienced this? Do any of you more experienced tuners have any suggestions? I'm all ears!