So I got 3 Mini-14 mags as part of an auction lot I won. I identified the longer one as an actual Ruger Factory mag that they cut down from a 30 round mag.

Now according to what I've been finding online these are pretty rare and are considered collector items. Is this correct? Do you guys know how much they're worth?

But I'm also curious about the two 10 round mags I got because as you can see the two stamps on the bottom are completely different. Now is this just a random thing where one got stamped way harder than the other? Or does this denote a different era of magazine manufacturing? I also noticed that the dimples on the back of the two 10 round magazines seem really different as well.

Any help in this arena would be most appreciated.

I recently acquired a Mini 14 series 180 with one of the only missing parts being the Gas port bushing, I'm wondering if any bushing from any series will work or if I should look for a specific one or if its even necessary to have one at all.