I recently picked up a used H&R with a 357 mag barrel. After reading much of the info one this site, I have a few questions. Okay, the serial number starts with BB so it seems this is a 1985 receiver. Cast iron? Meaning it is prior to SB1 or SB 2 designations and H&R/NEF would not have added that 357 barrel to that receiver. The number on the underbarrel lug does not match the last three digits of the receiver serial number. Markings on the receiver, suggest this was once an animal capture gun which I take to mean it fired transquilizers. I'm not sure what type of barrels are used for that work or if some type of sabot rounds are used. Anyway, from what I have learned, I can not add any barrels to this receiver other than perhaps a shotgun barrel which I'm not interested in doing. (would love to have a 32 magnum or 327 mag barrel) The main question I have is about the plastic trigger guard which is broken. Since this receiver is 1985, anyone know what the correct part number for the trigger guard would be? Best place to purchase One? Any information, suggestions, and help would be apppreciated.