The 6th edition of the Hornady manual gives a load for 165 to 168 gr. bullets with RL-19 starting at 64.9 gr. and going up to a maximum of 74.5 gr. for a maximum load that gave 3,100 fps in their 24 in. barrel. For RL-22, the starting load was 66.9 gr. and the maximum load was 79.1 gr. with a maximum velocity of 3,200 fps. That said, you can use the data from any reloading manual for 165 to 168 gr. bullets as long as you start low and work up.
You do have a manual don't you? If not, I would recommend you get two or three.
Also, I'm assuming by "300WM" you mean 300 Winchester Magnum and not 300 Weatherby Magnum.