At least 20 years.
That is not the model number, but the Ranger marked shotguns were sold by Sears before WW2.
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Your shotgun was made by High standard in 1960 for Sears. The model 21 was first introduced by Sears in the spring of 1958.
Sold by Sears Roebuck. Probably manufactured by Stevens.
Most likely it was Sears in the late 20's
I bought a sears 684 shotgun (12 gauge) at sears around 1979 , for $ 99
No age records, most likely a Mossberg shotgun, values $50-$75.
The Sears M300 (also sold under the label Ted Williams) was manufactured by Winchester. The M300 is almost identical to the Winchester model 1400 shotgun (with minor cosmetic differences).
Anywhere from about 1898 to 1989. Sears sold guns for a long time, and without more info from you, that's as close as we can get.
With such a detailed description of your shotgun, all I can say is that Sears sold shotguns, including .410 gauge, from the 1880's to about 1990.
An Eastern Arms model 101-7 shotgun is values at $200 to $300 in fair condition. In mint condition it is values at $450. This shotgun was sold by Sears.
A 30-06 is a Rifle not a shotgun You must have a pump 30-06 rifle not a shotgun and do you want to sell it ?