Thread: 260rem powders & barrel length

Looking for advice on powders & bbl length for 260rem. Recently acquired a 260 bbl which I plan to fit to my Model7 when the current bbl (708) is shot out. This will be a bush gun but want to retain enough speed to stretch out to 500yd or so when needed. I’m planning on running 140 AMAX, 143 ELDX & 140gn Speer HC.
Bbl length? Thinking 18 or 20. Not going any shorter but can I get away with 18in and still get north of 2700fps at muzzle with 140gn pills ?
And what powders would suit best for this in 260?
Have RL17 & 16 on hand, plus Superformance & most ADI powders. Don’t want to use RL26 as I’m rationing that for my big bangers.
Other powders worth considering?

I thought I saw a thread on this a while back but buggered if I can find it anywhere in the reloading or firearms sections ?!