I don't have the 350, but I have read some about it. I do recall reading that the 350 really likes JSB Diablo Exact Jumbo, RWS HP, and RWS SP, in that order. I've also read that the weight you should strive for are between 14-16 grains, but you're gonna hear mixed opinions on that.
What you could do is order an RWS sampler pack and see what your 350 likes the best.