Way expensive, but that's how it goes these days.
I settled on Accurate 4350 when H4350 became rare as hen's teeth.
Accurate 4350 is a good bit less temperature sensitive than IMR 4350, at least according to Hodgdon, plus I was actually able to buy a bunch.
IMR 4350, with some load development, will work quite well in your .260s, but if you shoot at temperature extremes you may see a good deal of MV variation.
This chart shows the MV spread between 0 and 125 degrees F.
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