I believe Shotgun News came out three time a month. One issue would have the big Sarco ad, one would have the Paragon Sales (Chicago, IL) with their neat WW2 cartoon style advertising.
I sold a Winchester model 52A .22lr rifle to an east coast collector in NY. About 4 or 5 hours later I got a call from a west coast collector wanting to buy the same rifle. He said he frequently lost deals to east coast collectors due to the time difference on mail delivery of the Shotgun News.
The Gun List did come out monthly and was definitely more organized when it came to types and models of firearms listed.
The pre internet days were a fun time to collect.