Powder preferences for long range rifle

I'm trying to put together a .300 Win Mag competition cartridge for a 1000 yard plus shoot match. So far I've got Lapua match grade brass, match grade primers and Berger 210 grain projectiles. All components have been weighed and matched. Looking for suggestions on a good powder for the distances I'm shooting. Trying to bring groups down to under 2" at 1,000. Any help is appreciated.

What make of rifle are you going to be shooting this out of? What make and model of scope, etc.?

Old thread, I know. But I wanted to ask the OP how he convinced Lapua to make him belted brass. Last time I checked, ( 5 minutes ago) they don't.

As far as powder, I've had excellent results with RL22, but that's in my barrel.

RL2