Your 48 should be a very good shooting gun. The fact that it has a fixed barrel will help accuracy.
I have an Air Arms TX200 22cal.
After having several false starts with hatsan's and other worthless air rifles I decided to get a really nice rifle. At first I was still not thinking straight. I put a UTG scope on it and UTG mount on my Air Arms TX200. That was a huge mistake. Then I put a vortex crossfire II on it. Things got better, but not great. I decided it was the mount. So I put a BKL one piece mount on it. Then good became great. I killed well over 400 rock Chucks with that combination. I liked that scope and mount but I wanted to take it to the next level. So I put a vortex Diamondback tactical 6-24 x50 FFP on it with a set of triple strap BKL mounts.
Putting quality scopes and mounts was tge key to changing my good shooting rifle to a unbelievable shooting rifle.