Congratulations on the new rifle. I am sure you're really going to like it. From reading a lot of posts and owning to many rifles myself.. when I take a new inline out on the range I normally see if they will shoot a 250 grain Shockwave, 240 grain Thompson Center Mag Express, Thompson Center Cheap Shots, and then some 245 grain Powerbelts (in that order). I have yet to see a rifle that did not take to one of them and shoot them excellent.

With 50 grain pellets, limit your powder charge to 100 grains. Maybe later down the road you can pick up some loose powder and a powder measure. Save some money with that combination.

My CVA inline likes 90 grains of loose Pyrodex RS for some reason. With that powder and charge it will shoot about anything I want to try. Good luck with the rifle and keep us posted.