What a putz. Does he not know that every part from every manufacterer will interchange. Heck thats part of what makes the 1911 thrive in todays market with all these space age gadgets that fire bullets. Sounds like this guy needs a basic course in the design and function if the 1911 platform..
Heres a simple list, easy to remember, but you can write it down if you have a memory like I do..
Pertaining to single stack 1911s ONLY..
OfficersACP/Compact framed guns (usually having 3" barrels or less) can use any single stack 1911 mag. From sompact 6 rd versions, sloppy 7 rd GI versions, fancy smancy stainless 8 rd versions with rubber bumpers all the way up to and including, if one were so inclined, one of those HI-CAP 50 rd. drums CTD sells, Why? IDK.. But to each his own I suppose..
The Commander and Govt frames, Including longslides, can use them all EXCEPT, the 6 rd compact mags..