To find the serial number on a Mossberg 151K, you should look on the left side of the receiver, just above the trigger guard. The serial number is typically stamped into the metal and can be somewhat small, so you may need good lighting or a magnifying glass to see it clearly. If you have difficulty locating it, consult the owner's manual for specific details regarding your model.
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You will not find one, since these were never serially numbered. That model was only made in 1950-51. Serial numbers were not required by US law on rifles and shotguns until 1968. And yes, it is perfectly legal. I collect older Mossberg 22s, and only those that were purchased by the US military ( Model 44 US for example) have serial numbers.
The best way to find the age of a Mossberg 500A Shotgun is simply to call the company's customer service line and have the serial number and model number handy. Mossberg has yet to publish a list of their serial numbers in relation to the dates of manufacture.
The Mossberg Model 800B was produced from 1964 to 1981. To determine its age, you would need to find the specific serial number, which can help identify the year of manufacture. If you have the serial number, you could look it up or consult resources specific to Mossberg firearms for more precise dating.
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If you are unable to locate a serial number on your .22 rifle, chances are it was manufactured before 1968. Until that time, .22's were not required to have serial numbers.
152k were manufactured between 1948/50 to 1957 and were not stamped by the manufacture to keep costs down. The law requiring serial numbers was not passed until 1968.
The Serial Numbers are along the Left Side of the Receiver just Above the Stock.
Your rifle which was a Mossberg model 320 which was made for Montgomery Wards(Western Field) was made from 1960-1980.Any firearm made prior to 1969 did not require a serial number by law.That may be the reason you cannot find one.
If it's not on the left side of the receiver it doesn't have one, as they were not required before 1968.
your Wards Western Field model 15A was made by the Mossberg and Sons firearms Company.This is the Mossberg Model 83.This shotgun was made from 1933-1946.As such there may not be any serial numbers because they were not mandatory on firearms until the year 1969 with the passing of the gun control act of 1968.