I'm not familiar with this specific revolver. It would help if you'd specify which screw? If you're talking about a break top, you should have removed the cylinder first. The two break tops (one Webley/one Hopkins & Allen) I can faintly recall, after removing the bolt at the hinge, one opened the hinge and gently pulled while flexing the hinge open/closed.
The hinge is generally very tightly fitted. If there's no good reason to disturb it, I'd just leave it alone. Cleaning doesn't require removal.