I've found the WW white box to be very accuate from my 10fp.....although it is older manufactured ammo, which may or may not mean anything. Most groups will cover a one inch target.
Also had very good experiences with Ultramax "remanufactured" 50gr NBT,, not as good with their 50gr TNT.
Though the best "one ragged hole" groups come from handloaded 75gr hp Hornady bullets using IMR 3031. I've not tried too many different powders in this rifle.....since I tend to stick with a load that works well when I find one. It will shoot good with most bullets 40gr to 75gr.
The 10fp is a very capable rifle for the cost,,in my opinion. Hope this helps.