Hmm, after cleaning, is the area under the extractor star not just clean, but also oil-free? According to S&W, the surfaces in this area of its .22 rimfire revolvers need to be kept oil-free, so as to minimize the fouling that gets trapped there and the cylinder binding that results. Drying the area thoroughly makes a big difference, in my experience. Just a thought.
Also, I seem to have more problems with .22 WMRF ammo than with any other. I remember one bunch of Winchester ammo whose cases tended to split lengthwise. At first I thought the cause was my Model 48--until I found that the cases also split in my brother's Single-Six. Anyway, ease of extraction can vary from brand to brand, and, as Mike says, .22 WMRF can be very dirty.
That said, I have to admit that, ammo aside, my Model 48 is the most problematic S&W I own. When I first bought this gun, ejection was terrible. I could have taken a carpenter's hammer to the extractor rod and still not gotten the cases to eject, regardless of the ammo brand. I had to drive the cases out one by one with a cleaning rod. Finally I shipped the gun to the S&W service department, which polished the chambers, resulting in considerable improvement. But ejection still gets relatively hard relatively soon, unless I wipe out the chambers from time to time at the range with a Q-tip or a dry patch.
Problematic or not, though, I still like my Model 48, which was made in 1981. I even had S&W upgrade it with a full target hammer and target trigger. It's a keeper.
HTH.
