Just received this info in the Brownells Gunsmith Kinks for April 2010. Wanted to pass it along just in case any one runs into the problem for which parts are no longer available.

MIM Stops
-- Phillip Lebow

I got in an old S&W 5-screw N-frame that was throwing past the stop on DA and SA due to wear. It badly needed a new cylinder stop, the original being rounded over.

I was out of 5 screw cylinder stops and none were available, so I ordered a couple of MIM stops from Brownells, along with some Loctite #638.

The MIM part has a hole in it for the return spring, as all the 3 screw and later S&Ws have, so the plunger system on the 5 screw won't work. The plunger just falls into the spring hole and the stop won't reset.

I cut off a 3/16th piece of a # 32 drill shank and glued it into the hole in the MIM stop with Loctite #638.

When it was set, I filed the drill stub to the contour of the cylinder stop body, and polished it. Works swell as the MIM stop is wider than the old forged stop. With the addition of a new hand, and a little lubrication, the old N Frame is tight as new and no longer throws the cylinder past the stop.