I have one that my old man handed down to me, its probably 15-20yrs old. He didn't shoot it much, but claims he always shot 3" shells through it with no issues, and i shot it for one turkey season with no problems. A friend has an 870 that has "magnum" engraved on the receiver and says that only those with this stamp can shoot the 3" shells. According to another friend if the serial # has an "M" at the end, then they can shoot the 3" shells. Mine does have an "M" at the end of serial number, but no "magnum" stamp on the receiver...anyone know if I am ok to continue shooting the 3" shells? thanks.

my mossberg says 2 3/4 or 3 " on the begging of the barrel and my dads JC higgins says it in the same area. i dont know if remington does it or not but i wouldnt untill i get it checked out for sure

If it has a M in the serial number it's a magnum but the barrel should asso have for 23/4 or 3 in shells Marked on the lefthand side of the barrel in front of where it joins the action

I bought an 870 last december, just the basic model. The barrel says it takes 2 3/4" or 3". so your probably fine.

As far as I know, all Rem 870 Express guns in 12 or 20 gauge are chambered for 3" shells..

+1 Any shotgun intended to use 3" shells will be marked "2 3/4 in. or 3 in." on the side of the barrel.