Naaah. I know what a chamfer is, and pulvinated is a better term here. A chamfer is more abrupt -- happens just at the edge, and specifically speaking, involves a distinct (usually 45 deg.) change in angle.
Like so:
It could also be "radiused" which would indicate a rolled-over edge describing a quarter of a circle, like in these counter top explanations:
Pulvinated describes something that has more of a sweep, or "belly" to it. Mostly used to describe architectural columns which are slightly fat in the middle (truly straight-sided columns look a bit hollow to most observers), it indicates that there is a gradual, fair curve across the surface.
When I look at this Ruger's cylinder, it doesn't have a chamfer at the front of the cylinder, nor a radiused corner. It appears to have a gradually reducing, curved outer surface that sweeps down from the full diameter of the cylinder at the beginning of the flutes down to a smaller diameter at the front. If you look under the top strap right above the barrel stub/forcing cone, you'll see a slight triangle of daylight with a very lightly convex hypotenuse, indicative of that curvature.