I don't know. But your Express probably has dimples in the mag tube that will need to be drilled out if you want a functional mag extension. I had to do it to mine.
So, you want an 18" barrel, but the description specifically states:My end goal is to get an 18" barrel, Spec Ops Knoxx pistol grip stock, magazine tube extension, and side shell holder. Will this barrel pose a problem with the tube extension?
Thanks in advance.
I think you want the 18.5" since you'll add a mag extension later.These are called Home defense barrels because they have the detent ball and at 18.5" they end flush with the Remington Law Enfocement 2 round extension where the 18" barrel will end about 1/2 inch behind it. They also fit the 4+1 models as the your magazine cap simply pushes the detent ball out of the way.