I have seen a Chinese broomhandle: a new Chinese made
receiver for a Model 712 Schnellfeuer parts set, without the
select fire option (semi-auto only). The 712 receivers were
not importable.
The one I saw was in 9mm and used a 10 round detachable mag.
It would probably accept a 712 20 round magazine.
The receiver was new, and was grooved for the detachable
shoulder stock holster. I have an original Broomhandle and
a reproduction shoulder stock holster and ATF paperwork showing
it legal; however, the same letter stated the gun with the
newly manufactured receiver would be treated as a new gun and
would be legal only if registered as an NFA item ($200 tax).
I could not possess both my original Mauser and shoulder stock
holster and the Chinese broomhandle without the NFA tax stamp
so I passed on the Chinese broomhandle (the dealer told me it
was just as well: the accuracy of the Chinese model was not
so good). The Chinese receiver was somewhat like the Italian
Navy Mauser broomhandles: the sides were flat and did not have
the distinctive milled recesses of most broomhandles.