My recent repro mags are quite different from the originals and are easy to differentiate. Most have flanges and do not have cartridge markings but a couple are flangeless and marked. They are not as heavy as originals either.
I have a 5 round mag that I think is a repro that is extremely similar to my originals in every way. The "stoutness" as mentioned above is the most obvious difference but there are some other minor ones if one compares them side to side. They are close enough that it is possible what I think is a repro is actually a different version of an original as this magazine is quite old. It came with a prison gun which adds to the possibility of it being a later version "original". There is a book on these guns but I haven't been able to lay my hands on a copy. There might be an explanation on this in there.
