I'd submit a guess that your frame is from the 1940's ... those metal tabs are actuall called 'window points' and loosing them to the 'framer' is not exactly a big deal , although a Pro would have kept them for you .
It's a shame the paper backing was destroyed , though , as sometimes info is printed/written on it .
Although I do some of my own framing , I think it's best to take such items to an experienced pro (like ironlord1963) , not the run-of-the-mill framers .
Many items have been framed with older , acidic elements & will destroy/damage artwork over time .
I always consider the cost of re-framing/matting/etc. when buying an older framed item .
Window points are still used today , although they're smaller than the ones on your frame , and are used to install window glass in wood window frames with a staple-gun type tool .
In actual $ value , I'd say the frame alone was worth your $20 .
Also , you're not alone , in having a less than favorable experience with such retail framers .
Earlier this year , while my 'usual' & excellent framer was away to Europe on an extended vacation , I tried a local chain-type-framing-shop that advertised "Museum Quality framing" .
I had sold a watercolor that I needed to deliver to the buyer in a week ... all I really needed was some acid-free matting cut , to replace the existing one .
I ordered the cut (with an exact diagram & measurements) & color/texture matting I wanted .
It took them 4 days longer than the time promised , it had been cut six (yes , 6 !!!) times & still was not right ... I wound up paying for the mat'ls & brought it home (disgruntled , to boot) , cut it right & it took me a few mins. to do .
Never again !
