My .22 Katran Compact(tube) came shooting 21.02 fpe for approximately 48 shots. It seems very pellet picky. Shooting with bipod off a bench, I was only able to get descent groups(3/4 inch at 25yards/1.5 inch at 50yards in light wind) with Hades and JSB 15.89, but had some poi shift and a few wild flyers.
I removed the bipod(used bag for front rest) and put a half turn on the hammer spring took the JSB 15.89 from 772 fps to 782 fps. This tightened the groups(.25 inch at 25 and 1 inch at 50yards) and eliminated the poi shift. Still get the occasional flyer tho.
No slugs were very accurate. The best result were with 21g H&Ns or 20.2g NSAs(1 inch at 25 yard and 1.25 inch at 50yards)
The simple 16 round magazine was a bit slow to load, but seemed to function fine with no issues. The gun feels awesome in your hands with a palm swell grip and tactical style fore end. Light, but solid. Regular key lock attachments don't work well because there isn't enough space between the rail and the airtube, so you have to buy the ones from Airmaks. The fore end rail flexes a bit toward the tube under pressure, too.
Folding stock is the best I've ever held. Solid lock up with no flex or wiggle. One push on the button and it smooothly releases until it is magnetically locked in the folded position. Best part of the gun!
Without an aftermarket moderator, it sounds REALLY LOUD. DonnyFL Tanto, Tatsu or Hugget Astille quieted it down nicely.
I have had to work to get the accuracy I need, because I WANT to like it soo much.
Edit: Forgot to mention how AWESOME the trigger was. 1lb 1oz with a crisp break right outta the box.