remington 870/ 11 87 supermag receiver longer?

[JTF#]

is the receiver on the super mag 870 11 87 Remington guns longer then there normal 3" mag guns? or is the shell port just bigger?

 

[ARWEN ACE]

receivers are the same, ejection ports are longer and have a few different parts

 

[VLT79]

As already stated, the recievers are the same length and the ejection ports are longer. Remington designed shorter breech bolts, to allow the longer action stroke needed to cycle the 3.5" shotshells, to which they added a nifty sliding cover/shield to close off what would be an unsightly opening at the rear of the ejection port.