I use AA Fields in my 410K, they're about 15.9 grains (Heavy-ish and better for PCPs)
They have one of the best BC of any pellet according to chairgun.
They are highly regarded on here....which is the chief reason I use them.
They are accurate enough to consistantly hit a 20 mm zone at 55 yards bench rested.....and there's better shots than me on here.