Hello again B.C.
I'm reading huge cautions of sending the .22mag down a S&W L.R. barrel because of "possible" over pressures???? You have actually tested your theory successfully but it's hard to overcome the decades of mindset to the contrary. There is so much metal around a .22 barrel and cylinder of a M-17, 18 (being it's an under-bored .38) doubt the little .22 mag has the power to do any damage.