I've been thinking about trying Reloader 7 in the 454 Casull. Your input is certainly welcome, even if you are just daydreaming on the keyboard. Who knows where it might lead.

I am curious to see how a slower powder like this will perform for noise, flash and recoil and accuracy. And I wouldn't mind finding a load that was louder and flashier, for that matter

Would this be an even better choice if you went to a heavy bullet, like 325+gr hard cast? Or would a little 250gr be adequate and even safer or more effective? They are certainly cheaper.

I have no experience in loading larger calibers, but hey, this is benchracing isn't it?
When I picked a load for my .357Mag, The usual powders most folks load in .357 were actually too slow for a 4" barrel. I wanted whatever propellant I picked to be completely burned up by the time the bullet got out of the barrel. Instead of H110 or W296, I chose Blue Dot. Blue Dot seems to be the most efficient powder for my application. Muzzle Blast was cut way down. Speeds are pretty good for a 180gr bullet from a 4" barrel.
In theory anyway, I wanted to get as much powder as possible to be burned in the barrel, pushing a bullet, not making noise and flash outside the gun where it does no good.
There is my two cents worth.

ZM

I'm hardly and expert reloader. but with h110 and lil gun can't you fill the case and use a compressed load in the 454. I can't see the point in using a slower powder unless there is empty room in the case when using faster powders that you could use by filling it more with a slower powder.

from what I've heard lil gun is supposed to be the powder in the 454. anyways try it, if it works then fantastic if it doesn't your out some bullets primers and powder, no big loss.

I've expermented with these in my rebored Ruger 454 Cashull, where I try to keep the loads from starting to the middle loads but not hotter:
Hornady 300,
1. AA2200 (32) Fed Small Rifle Mag primers 2 7/16" x 3 at 25 yards
2. RL-7 (30.5) Fed Small Rifle Mag primers 1 1/2"X3 at 25 yards
3. IMR4198 (29) Fed Small Rifle Mag primers 2 1/4" x 3 at 25 yards
4. WW296 (28) Fed Small Rifle Mag primers 2 5/8"
x 3 at 25 yards.
The loads from top to bottom are mild, with black blowback, next two slighly stronger with a little blow-back and the ww296 is strong. The velocities are estimated as 1100, 1250 and 1300 fps.
Remember as the powder gets slower you'll reach a point where the black powder residue, is a tell tell sign that the pressure was not great enough to seal the chamber. The 2200 is good but you run out of case capacity before you reach the pressure you need to seal the chamber, but this load is fun to shoot. The RL-7 and IMR 4198 are heading down to the ww296 from slower to faster burn rate and perform.