[wrench]

The last side arm developed for mounted cavelry in the US Army was the 1911 Colt 45ACP.

A version of it is still used today in Iraq by Spec Ops and Marine MEU units.

Imagine a horse pistol now ridding in a Hummer?

[Little Ray]

Don't forget the M1911A1 designed to replace a .38 cal Colt double action revolver. It was designed in .45 cal because the .38 did a poor job at stopping amok Moro warriors; the Army actually went back to the M1873 Single Action Army, because the .38 was so inadequate.