6.5 RPM and RL-17

Nope, using much slower powder. The rpm is in quickloads though if you have a bullet and coal maybe someone can run some numbers for you
 
Shooting Times article on line says the 6.5 RPM case holds 82.5 gr of water and from a few sources the 264 win mag holds 81.5 to 82. So they are very similar.

There may not be any RL-17 load data but there is 264 Win mag H4350 load data for a 140 gr bullet on Hodgdon's site. Nosler's site also lists H4350 heck they even list IMR 4064 which most of us would consider too fast. Alliant lists RL-19 as does Nosler load data for a 140 gr bullet for the 264 Win mag which just slightly slower than H4350 and RL-17 in burn rate.

H4350 is considered the same burn rate at RL-17. While it may not be optimal it could work. Perhaps you can call Alliant and ask?
 
That powder is much too fast for that case, unless you are using very small bullets, like 85 grains or so, even then it's less than ideal. In the Alliant line, I would consider RL19 the fastest useable powder, and RL22 or slower to be more ideal.
 
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