Swapped out my Slug “A” Liners in my 600mm FX Crown and Wildcat MKII .25 for the Superior STX liners. They’re power tuned, but I sling pellets and slugs accurately with them both. JSB’s and NSA’s of various weights. My Wildcat MKIII Sniper came with a 700mm Superior STX liner, and it shoots very accurately also. Almost a couple months and I think the barrels are very good. Again, keep in mind that part of shooting accurately is much on the shooter. But the barrels are good and I like them a lot, very accurate!