Re: H870 or H1000 Loads for 65x284 ?
I've shot somewhere short of 1000 rounds of 6.5x284 loads so take this with a grain of salt.
IMHO, if you're running loads on a short action or a long action, you can't safely use anywhere near a full case of H4350 or a full case of H4831SC which are indeed arguably the two most popular powders used in this case. Seating bullets where the boat tail/bearing surface junction meets the neck/shoulder junction of the case you can fit 59 grains of retumbo in the case with only very minor compression. 59 grains fill it right up to just about the bottom of the neck. Using 140s I've seen well over 3100 foot sec with that combo. And yes it is hot. Is retumbo too slow for the 6.5x284? IMHO, no. IF you use a full case of it.
As far as H1000, you can use 55-56 grains under the 140s seated long without major pressure signs. There is zero compression with these charges and are pretty much max loads. 3000 foot sec plus or minus is the norm. At least with a custom tube and snug chambers. This is also on the warm side but not hot. Too slow? IMHO, no.
I've had the best luck in the accuracy department with H4831SC. That said, max loads leave a lot of air in the case. Max loads for me have been 51.5 grains in the past at 2950 foot sec and were quite warm. IMHO, this powder is acceptable but on the fast side. My max loads for H4350 was 47.0 at 2950. This powder is way too fast for a 60 grain case but it still works ok.
In factory offerings or short action loads, H1000 and retumbo may be a bit slow but for customs loaded for long actions, they're just about right.
I ran R22 and 140s over the chrony with loads that were below zero against loads over 100 degrees and the velocity spread was not bad. I don't remember off the top of my head but it was surprisingly low. This was a top end load too.
Long range shooting is a process that ends with a result. Once you start to focus on the result (where the shot goes, how big the group is, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.