I have a 258A 20 gauge shotgun, but mine is marked as a Stevens rather than a Savage. I dated mine to the 1950's, so I'm not sure if Savage and Stevens were affiliated with each back then other or not. I had another bolt action shotgun of some make - a 12 ga. - and when I traded it in, the shop owner referred to it as a "bread and butter" shotgun.
I believe they were fairly common back in the mid 1960's (and before) as simple, affordable and reliable guns, often sold at places like Sears, Wards or hardware stores that didn't tend to carry real high end guns. I like the mid-20th century vibe of my gun, and it's the visual match to the 1930's Steven's Buckhorn .22 rifle that I inherited from my dad.
Some people complain about the scarcity of box magazines on these old guns, but I found an extra one for mine at Numrich. If you have any feeding problems on these old 258A's, make sure the action and mag well screws are snugged up tight. As I recall, this stuff can be accessed by taking off the metal plate around the mag well. I snugged mine up and it feeds beautifully. They may need to be snugged up now and then, or use Loctite or Guntite.
Oh, and another thing to be aware of - the mag only holds two rounds, not three.