91/30designation came out whenthe Soviets accepted the Dragoon length Mosin with updated Metric sights and a front globe sight. There were a few differeing variations as rounded recivers were introduced, slowly, and the previous "Hex" were phased out. It took almost 5 years for the recivers outter dimentions to be changed in all factories makeing Mosins.
A 1930 barrel on a round reciver would be cool, so tell us, what is the Tang date onthe reciver? its under the reciver tang, the metal extention that the bolt passes through at the rear of the reciver.Youll find a year stamped under neath (gotta take off the stock) and youll find out if you have a 1930 barrel on a later made reciver, "OR" you may just have one of the first round recivers with an appropriate date, and therefor very collectable.