Real good example of how little chunks of the stamp can be missing/broken.   

I got this, but not sure what it is, but 21 million serial number ending in B. I see this is the same importer as your 101 listing under military importers. The arsenal stamp is missing some sides and stuff, but it looks like 6626. Also the rifle is marked Norinco. The three type 56 characters do not have much detail.

PT Hunter had a very different 5 rounder.  Made specifically for that model.




Jstin's is much simpler.

The five round mags I believe were available as an aftermarket item after the Polytech Hunter.  They are still found new occasionally...with Made in China in script stamped on the bottom.  They sell for about 25% higher than a real factory mag does.  Some states require five rounds or less for hunting....they get quite the premium around hunting season.  I have one for my scout SKS...they make for a nice concise underbelly as FC mentioned for bench use.

It's been mentioned before, that someone really put a lot of work downsizing these from what likely were original magazines.  It would have been awesome for Canada to get these instead of the plugged/bastardized factory mags....everybody would be happier...except for the gun shredders who profit from parts from otherwise perfectly healthy guns....

Not hard, just sand a bit and fit, sand a bit and fit.  Eventually it goes on.

Here are my Russian and Serb cousins.