A 2-3/4" barrel measures 2-3/4". Same as a 6" barrel is 6". The 2-3/4" will be 3-1/4" less than 6".
Will a shorter barrel be slower (assuming same ammo)? Probably. Louder and kick harder (assuming same ammo)? Probably. Handier and weigh less. Probably.
I like my 5-1/2" Bisley for what it does (.45 Colt). I like my buddie's 2-3/4" 69 Smith for what it does. Different guns.
I can load either one to make it do what I want it to do (within reason).
You pick the barrel length to suit your purposes, arbitrarily comparing it to other barrel lengths is an exercise I've never understood.
