The whole barrel steel thing was extensively discussed in print 20+ years ago when a barrel blew up during an ASSRA match. I will try and find you the print citations this evening. This topic was also covered on the old Shooters Talk board, if anyone has that archived. What I remember is, as Brent has noted, that the manufacturer specifically disapproved of the use of the material in this application. It will not stand the shock loading. I also remember that some barrel makers left the business and most others started using decent steel (which is harder to work). I personally view as suspect any single shot cartridge barrel from the 1960's-80's unless I know where it came from and what it is. It was unfortunately common for muzzleloading barrel makers to also make barrels for cartridge rifles and many of them used material barely better than screw stock.
