I have a Umarex / Walther CP99 (pellet, not BB). It has the rotary magazine. One of the more expensive of the "cheap" guns.
No Glocks for me. Don't like the grip angle. I have a .45 cal. Glock. Doesn't have that many rounds thru it, and I've owned it for over 30 years.
I was surprised at how well the CP99 shoots being that it has such a short barrel. The trigger is, well, it has one..! I put a red dot sight (Venom) on it, cause I can't see well enough to use the little "iron sights".
I have a couple other "cheaper" pellet and BB guns. All pretty much junk as far as I'm concerned except this one. The Sig P226, it wont even pierce the air cylinder. I tried several things. Nuthin reliable. One of these days, I'm gonna take a torch to it and melt it into a little puddle. I have a Tanfoglio, CZ Race gun. Had to do a bunch of work to it just to hold the barrel solid in the frame. IF...it hits the 8-1/2 x 12" paper at 20ft. I'm lucky. The CP99 will at least hit in the black (three rings) with most all shots at 20ft.
Mike