I have one for my mossberg. It measures .660 It does ok. I have dones some extensive pattern of buck shot with it. Remington and Estate #4 2 3/4 shoot the best for me. I can put 14 pellets in the shootnc target at 40 yards. At 60 yards 7 pellets on target. I can only get about 40% of the Hevi Shot dead coyote T shot to hit target.
My son has a Mossberg turkey gun with a .670 tube and out patterns my Dead coyote tube all day with everything. Again it's like rifles, each shotgun patterns better with one shell than others. I found it interesting that no 3" shell patterned well at all with my gun.