[Peter M. Eick]

I noticed above the forcing cone of both of my pre-war N frames (registered magnum and heavy duty) there is a nicely rounded lightly machined "divot" out of the top strap. What was this divot for?

Just curious....

[Old Fuff]

It was called a "fouling cup" and the purpose was to leave a space where (black or semi-black) powder fouling and lead splatter could collect and not cause the cylinder to bind. They disappeared about the time the .357 Magnum was introduced. I'm a little surprised your registered Magnum has one, but it might have been built on an earlier NT frame.

[Peter M. Eick]

Thanks, that makes sense. The registereds is very small compared to my heavy duty but then again, the heavy duty pre-dates the registered by about 5 years, so it may be they just changed the size of it.

I appreciate the help.

[Old Fuff]

Because of the higher pressures and the fact that no one was loading black powder or semi-black into .357 Magnum cartridges led Colt to drop the fouling cups in Magnum-chambered New Service, Shooting Master and Single Action Army revolvers at the time (about 1935-36) that they started to offer this chambering. I'm pretty sure S&W did the same. I don't remember seeing fouling cups in pre-war/non-registered .357's but I may have not paid close enough attention. In the future I will.

[Tamara]

My '36 .38/44 Heavy Duty doesn't have one, although I did just notice it has the slightest evidence of flame-cutting. Considering that it spent the last 60-ish years of its life as a Bullseye gun, it makes you wonder what it saw before its pampered target gun days commenced. :scrutiny: