IIRC the only thing a 3" has to offer over 2 3/4" slug shells is maybe 200 fps..... not enough difference if you ask me
I bought a box of 15 Winchester 2 3/4" grey box and a box of 15 of the same in 3" and never noticed a difference in accuracy, but there was a slight bit more recoil with the larger
Only reason I bought the 3" shells was cuz my 77H has a 3" chamber....... but for the sake of my cheek and shoulder I stick to the 2 3/4" shells and a cheekrest with padding
Also, I dont remember any 1100 that was chambered for 3" or bigger, I thought that was why the 1187 was made to replace it? If I am wrong please inform me