A couple of weeks ago:
From a 26.7" barrel. That's a little warm though.
Since this is the first summer I've used Nosler brass, I think my initial (made in the winter) assesment of not having to drop that load with that brass was in error.
Anyway, as you can see my standard load of 101 US869 with Nosler Brass makes 3045 in 80 degree temps. Yes, that's too warm, the brass won't last very long at that.
However, that's the load I'm going to be using without change. Out of a bucket of icewater (refridgerated all night before) that same load chronographs 2970. Perfect.
In short, you can add 100 fps at least to your expectations when using US869. 2950 from a 26" 300 RUM is perfectly mild. Well over 3000 fps, yes, is pushing it. I'd drop that load 2 grains for summer to keep the velocity around or below the 3000 fps mark in the heat.