HuntnShoot,
I long suspected a lot of the reason for the "fouling" reputation of the .17 Remington was due to the dirty-burning spherical powders often used in factory ammo when it was introduced. It would have been logical for Remington to load them in the .17 because they'd flow easily through the small neck.
I bought a 700 built in the second year of production to test this theory, which hadn't been shot much at all, and never had any fouling problem with Benchmark, Varget or Big Game, a very clean-burning spherical of about the same burn-rate as 760. But 760 isn't particularly clean-burning, though the latest version seems better than it used to be. I have been told, however, by people who bought early 700's that some of those barrels were pretty rough.
As for the powders such as 2495, TAC, H322, etc, that you list as "appropriate," they're actually a little fast for the .17 Remington, especially with .25's. They'll work, but they're better suited to the .223 than the .17 Remington, which has a little more powder room than the .223 with a considerably smaller bore.
Hence somewhat slower powders work better; generally powders that fill up a case, or come close, without producing excessive pressure will produce the highest velocities.
4320 is a classic, since it's a little slower than either of the 4895's, but Hornady lists 760 as producing the highest velocities in the .17 Remington with 25's, and it's slower than 4320. But even 760 still doesn't fill up the case, the reason I tried Big Game, which is just a little slower than 760. Plus, Big Game burns cleaner.
I tend to run a lot of spherical powders in .17 caliber cartridges, because when loading with a powder measure they flow through the small necks a lot easier. Finer-grained extruded powders also work well, another reason 4320 has been a classic .17 powder.
