Just purchased my first gun ever and choose the 15-22 for many different reasons, but would love some feedback on the best ammo to use with this rifle. Signed up to gunbroker.com and was going to buy a bunch of ammo in one quick swoop but want to buy good stuff. ALso and forgive my newbie question what is difference between the different grains ie 34 or 40 and is one better for this rifle then the other