I'd agree w/Kirby on this one. US869 may be a little slow for the 200 gr and lighter bullets. I'm trying for the reasons he stated. I've already got a killer accuracy load for the 240 SMKs w/Retumbo so I just thought I would give the US869 a chance in the RUM w/the 210s. Thought it might open up a space on my powder shelf. I'm also shooting a 30" bbl.
From what I've seen by shooting it in conditions from 20 degrees to 90 degrees I'd say There is about a 100-150 fps variation. Again this is just by comeups and extraction can get a bit sticky as temps get up over 75 if I don't keep the ammo cool.