Black Mamba,
Please read about and use the warning in the sticky,
here. It is required for unpublished loads.
1972RedNeck,
CAUTION!
First: GRT (Gordon's Reloading Tool) is interior ballistics simulation software, like QuickLOAD. These programs do not fully take thermal losses and friction into account, so they tend to err on the low side with pressure. In particular, this is most exaggerated with reduced loads, so the pressure from the suggested load is likely to be higher than GRT predicted for it.
Second: WC296 (H110 and 296 in canister grades for handloaders) is a St. Marks propellant that does not like to be downloaded or has less than about 85-90% case fill. You can get lower pressure using it behind a heavy bullet because the bullet's high mass delays acceleration enough to give the powder time to get its burn underway. With lighter bullets, it doesn't have that advantage and can squib out. Hodgdon had a warning on its (currently confused) load website that published loads of H110, and 296 should not be loaded down more than 3% because this powder has a propensity to extinguish at reduced levels, especially when a revolver barrel/cylinder gap is being jumped, leaving a bullet stuck in the barrel for the next round to smash into. Since extinguishing is highly inconsistent, the next round is likely to fire normally, so its bullet rear-ends the stuck one, something that causes barrel bulging or even a gun burst. So you have to be extremely cautious about using this stuff at reduced levels, possibly checking your bore after every shot.
Third, slow powders tend to burn poorly at lower pressures anyway, leaving lots of fouling and unburned powder particles around. They also tend to burn inconsistently when this is happening, giving large velocity spreads.
You would be better off skipping H110 for your application and trying to find some 2400, Power Pistol, Accurate #7 or #9, or something else less touchy than WC296.