· Super Moderator
EDC: SIG P938.
I think it's because the 1911 is a large-framed gun, and the .40 is a medium-sized round. You can put .40 in a smaller gun, and the 1911 will accept larger and/or more powerful rounds, so it's sort of a "why"? .40 1911s are very common in practical pistol competition, in both single stack and hi-cap persuasion, but it's only a matter of wanting max capacity and cheap brass.