Frank, I don't know of anyone who has used the WC852. I have no clue where to start with that powder. My first build loved RL-22 also, but seemed to me to be a pretty dirty powder and it did carbon foul on me after about 162 rounds. Got the gunk out and switched to H4831SC and gun is just as accurate and does not foul nearly as bad.
As Tiny 68 said, RL-22/4831 class is great with 105's, if shooting 87-95 class, I would try the RL-19, H4350, Viht. N160 burn rate class.
As to your WC852, maybe email Richard Franklin customrifles@hughes.net He has built a few hundred of the 6MM AI'S and owns a couple. But I have a feeling he will sway you over to any of the powders we have mentioned so far. I just ordered a stock from him and he is fast to reply to email.
Frank