I have an extra Remington barrel that I found buried in my gun room. It is a Remington made barrel, but I do not know if it fits an 870 or an 1100. Can anyone tell me how to determine which it is?

Thanks!

An 1100 barrel will have gas ports in the cylinder that slides over the mag tube.

And that cylinder which slides over the magazine tube will be completely different.

The barrel extension on the 870 is short - roughly 1"+. The 1100 extension is at least two inches.. (Don't have one at hand to measure)

As has been pointed out the barrel extension ( the part that slides into the action) on a 1100 is much longer than a 870 but also the portion of the part that slides over the magazine tube is also much larger on the 1100 as well as having the gas ports as mentioned above. The 870 is probably about 3/4 " while the 1100 is about 2-2.5". If you could post pics it would be much easier to ID it for you.