As near as I can tell, it's not a Magnum.

[RicMic]

I just picked-up a Remington 1100.  The ejection port measures 3 1/8" and the serial number has a M prefix and V suffix.  So I'm guessing from what I've read so far this is NOT a magnum reciever.  Any 1100 experts out there?

[Graybeard]

Looking at a couple of my Remingtons the 870 3" magnum measures exactly 3" and the 20 gauge 11-87 3" measures the slightest hair more than 3" so I'd guess yours is certainly long enough to eject 3" shells but likely not 3.5" shells. Generally the reciever on a magnum gun says MAGNUM on it and the barrel should tell you if it's chambered for 2-3/4" only or also 3".

[RicMic]

My barrel says 2 3/4" however I'm wondering about the M prefix of the serial number on the receiver.  If it is a magnum receiver then I could fit a 3" chambered barrel to it.  Most references state that the M is a suffix not a prefix.  I was kinda hopin' for "You have a magnum!", but believe that it is a standard receiver.

[Graybeard]

My 870 Magnum has an M suffix but not prefix. The 11-87 magnum has no suffix at all and the prefix is not M.

I believe that unless your receiver has the word MAGNUM on it then it is NOT a magnum.

[huntswithdogs]

Most of the ones I've seen that were Magnums, had it engraved or stamped in the receiver. To settle any speculation, give Remington a call and ask them before assuming that it is.

[RicMic]

I had been assuming all along that it is not a magnum.  And I really don't mind as it cost me $249.

[Swampman]

For around $50.00 it can be a magnum.  All it needs is a new ejector.  Then you'd need a 3" barrel.

Gander Mountain will convert a 2 3/4" Rem. 870 to 3" Mag. (includes chamber and ejector work) for $125.00.

[LaOtto222]

I do not know if it will help It sounds like I may be too late to be of any help - I have a 870 Super Mag and it says so right on the receiver. At the price you paid, I think you did good. 

[corbanzo]

You could also try and slide a 3" shell in the barrel.  If it doesn't go it, it is cut for 2 3/4"  If it does, it is cut for 3"

[charles p]

I have an 1100 12 guage in 3" magnum and the serial number starts with "M".

If you try to slide a shell into the barrell, use a fired shell that is already opened.  I expect a 3" unfired shell might slide into a 2 3/4 chamber.  Not sure.  I have never seen a Remington barrell that did not state what shell length it was chambered for.

[island66]

Your 1100 is not a "magnum" receiver.  The M prefix simply means that it was built between 1974 and 1978.  The V suffix designates a 2 3/4" receiver.  You can install a 3" chambered barrel and shoot magnum loads with no issues or further conversions necessary.  The ejector is an integral part of the barrel and, therefore, does not need to be changed.  Remington offers an 1100 Steel Shot Magnum barrel that will work great on your receiver.  Give big green a call if you have more questions...800-243-9700.  Good luck.

Jason