If and when you start reloading for it try and find RL16. It is hard, but does still come up in a few places even though many say no RL powder in Canada in years. My last 8 lb jug was bought mid summer last year, so it does come up. Granted, this is what has worked best for me, and the 139 gr, and 26" barrel, but I imagine a shorter barrel will still be okay with it.
Tried all the other sure powders for it as my stock of RL was running low, and came back to RL after finding a restock.