You are probably familiar with how Remington 870 shotguns are made with different gauges. The most common gauge in the model 870 is the 12-gauge. This measures the diameter of the barrel. But what you may not realize is the length of the shells is also as critical to consider as their diameter. If you have 3 inches or 2 ¾ inches shells then you need a magnum receiver that can handle it. Of course, the barrel also has to be equipped to handle up to 3-inch long shells. If it is then you can fire them as long as you have a magnum receiver.

Remington 870 Police Magnum
Remington 870 Police Magnum

How can I tell if my Model 870 shotgun has a magnum receiver?

There is a very easy way to tell if your Remington 870 has a magnum receiver. Just look at the serial number engraved on the receiver and see if it ends with the letter “M.” If it does then you have a 12-gauge magnum receiver installed in your weapon. There are also more powerful magnum receivers that can handle even more powerful shells. If the serial number on your receiver has the letter “A” at the end of it, then this signifies that it is a 12-gauge super magnum receiver. These super magnums can shoot shells that go up to 3 ½ inches in length, as long as the barrel is chambered for it. As for those who are using 20-gauge shells that are 3 inches in length, you will need a 20-gauge magnum receiver for those. You can spot these if the serial number on the receiver ends with the letter “U” or “N.” This is a more unusual shell and receiver combination but for those who want extra strength in their firepower, this is the choice to have.

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  1. Ive a 870 Express with magnum receiver; thanks to this Webpage I now know. The issue is the so called “fully rifled” 1 turn in 36″ barrel (as stamped on barrel). This barrel has never had rifling, and Id not given thought to this aspect upon cleaning it many numerous times, beginning several decades ago. Ive purchased a deer hunting barrel with adjustable sights and unknowing without rifling. Where was the quality control back in them daze?


  2. My 870’s serial number ends with a C. The barrel has “12 GA. 2 3/4′ AND 3′” and below that “3 1/2′ ONLY WITH SUPER MAG RECIEVER” stamped on it; referring to your article I should be able to support magnum rounds, minus that part about the last letter. I was just curious to know what I can and can’t fire. Question being: Can I fire magnum and super magnum? Or just magnum rounds?

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