Moon clips
The moon clips, 2 rd, 3 rd half moon and 6 round full moon were developed for the m-1917 revolvers in WW-I as there were not enough 1911's to go around. Colt and Smith and Wesson made 1917 revolvers that used the same clips. Later used in S&W 1955/ M25-2 revolvers.
1911 uses detachable magazine, generally 7 rd (GI) 8 and 10 round aftermarket available.