The company that has made these mags is long out of business. I have owned these mags since aprox 1992-1994 when I bought a case of them. I can check if I have any doccumentation available & if so, will include a copy with any mag purchases.
The only marking on the mags are:
The letter "H" Varies among the mags
22H on the other side
The H & 22H are most likely mold Id's
The baseplate has the PAT.NO. 4139959