I haven't but I have one laying around (somewhere) that I might try out. The one thing I like about the used UTG I have one mine is that the reticle is almost perfectly set up for the rifle's ballistics. I can reach across the yard at will to a squirrel, about 95 yards, and 99.9% of the time it falls out of the tree. Rabbits same way except they ain't in the trees obviously. I've been over 100 yd with rabbits, .177 benjamin.
pellets. Pick up a tin of a bunch of different kinds and see what your rifle likes. Every one of them is different even the same models might like something different. Part of it is the shooter. I'm good with H&N target pellets. Work pretty good for me. Next item to address is--similar to bow hunting, you can't practice with a target head (or pellet) and expect to be dead accurate while hunting with a broadhead (or pointed pellet). You have to pick one that works for you, and you will use that and stick with it whether it be target shooting or hunting. Particularly pellets because, at least in my case, if I am plinking with a 10.7 gr pointed pellet and then stuff a 4.8gr target pellet in to shoot a rabbit, the flight characteristics are completely utterly different. The light "loads" are much faster and out to 75yd or so and much flatter shooting, HOWEVER it comes at a cost. Noise. They are LOUD (supersonic) just like a .22LR, sound real similar actually. Also they are bad sensitive to wind. So I picked the H&N pointed pellets that shoot the best out of mine and I plink with them and hunt with them. Just buy plenty so that you can do that, and get 'em before they, too, get banned or "limited". I wouldn't put it past those idiots in the white house to try to do it either.
Cleaning. If your rifle has that little "suppressor" on the end, be real careful about cleaning because it can grab and eat your cleaning cloth or cotton cleaning wipe.
Any of you tried dieseling yet? I did but it's so innaccurate that it's a waste of time, money, and waste of a good pellet rifle, at least in my case. What I would like to do, however, is find or make some .177 tracers as 99% of what I do is after dark.