I used to find that my old LG110 preferred the lighter mossies over the exacts.
Pushed at 780fps they used to be pellet on pellet at 50yds in still air but only with a clean barrel.
I used to have to pull the barrel through after every shoot overwise the first 5-6 shots the next shoot would be all over the shop.
Break-Free was my preferred barrel lube and I used to stick a couple of squirts in with the pellets for good luck.
If I didn't use break-free then the barrel would foul very quickly.