Finally figured this one out!
I removed the breeches and throughly cleaned it all and ( it was doing it on both my frames) still same problem, about 1/4 of every box resulted in a stuck firing pin. Upon getting home, I snapped until I got same occurance and with a flashlight I could see the centerfire pin spring retaining flange
was hung up under the flange of the rimfire pin and could not retract.
I then removed the breech and pins and using a fine file, stone, and diamond lap proceeded to slope and round the edges of the firing pin
flanges where they have paralell edge. Thus when they do twist slightly.
the rounded and sloped edge will allow the pin to retract without binding.
Last trip to the range showed occurance only twice with 30/30 and not at all on the 375 Win, that frame had previously been the worst offender.
So! If you encounter hard opening on the old frames, check to see if firing pins are not retracting.