7.62x39 magazines for an AR cost twice as much as 5.56 mags. But the ammo is quite a bit cheaper.
Word is that Ammo depot has a Shansi .45 cal Broom Handle Mauser for sale
http://www.google.com/imgres?imgurl=http://www.imfdb.org/w/images/4/40/C96-10.jpg&imgrefurl=http://www.imfdb.org/w/Mauser_C96&h=278&w=400&sz=38&tbnid=jjrz5B68uznZWM:&tbnh=90&tbnw=129&prev=/search%3Fq%3DShanxi%2BType%2B17%2B%28.45%2BACP%29%26tbm%3Disch%26tbo%3Du&zoom=1&q=Shanxi+Type+17+%28.45+ACP%29&usg=__UNPyKWbI3gYWcMaYfmaYep3Vces=&docid=smYbgEcF09Q8NM&sa=X&ei=q-rwT8O2Ocad2QWgqtz5AQ&ved=0CGAQ9QEwAg&dur=929
