Back in the day many knowledgable lawmen carried five inch barrells in the belief that it gave them a better sight because of the extra inch and a little more velocity, but would still allow a fairly rapid draw and to sit comfortably in the cars of the age. Many SAAs were five inchers. Now, that's dating back to the late 1800s up to probably the fifties. Same thinking goes into the decision to carry a full size 1911 instead of a compact model.