I bought my first Model 29-2, a blue 8-3/8" gun, NIB in 1977. It spit a lot of crap out of the barrel/clyinder gap. I thought it was probably just unburnt powder but the problem bothered me. It bothered other shooters on the line. I made a small plywood box about 14" X 14" with no top or bottom and took it to the range. I would lay it on it's side on the shooting bench and insert my gripped M-29 deep enough into the box that the barrel/cylinder cap was about half-way down the box. After a couple of rounds, I could see brass bullet jacket fragments as well as un-burned H-2400 powder granuals embedded in the surface of the wood interior of the box.
We then tried it using a cardboard box and it tore the box apart, debris and gas being ejected with power enough to tear the cardboard!
About then, early 1978 I think, S&W send an advisory to Model 29 owners encouraging them to return the guns to S&W and the service department would recut the barrel forcing cones to a different angle to help deminish the problem. I did, they did, and it did. I was happy.
My best buddy and I each had bought new Model 28 Highway Patrolmen, both 6 inches, probably not made too far apart, same era. The timing seemed okay, but both would blow little shreds of brass bullet jacketing out the sides and back towards us. I got a chunk almost 1/4" long embedded in my plastic lens shooting glasses, and buddy Dewey got a shorter but thicker brass fragment embedded into his cheek, which drew blood. We both suspected we were also getting peppered a bit by unburned powder as well, but it didn't stick into you like a little brass spears!
We returned both guns with an explanation and a bit of shredded bullet jacket each gun had sent into our facial regions, taped with Scotch tape to a 3x5 card. Both guns came back with the forcing cones recut, with much more of a bevel at the rear edges of the forcing cone. One of them had a new hand installed, as well. The problem ceased.
