View Full Version : Mossberg 500a Barrel and Magazine tube

January 13, 2013, 02:25
Where can I find a 18" barrel, and an extended mag tube for a Mossberg 500a? Im looking to turn it into a sort of trench gun.

January 13, 2013, 10:06
I think to get an extended tube for the Mossberg 500 series, you'll need to go with a 20" barrel. As you probably know already, you can't just screw-on a tube extension, like you can on a Rem 870.

You need to look for a 20" barrel and a replacement mag tube for a Mossberg Model 590. I believe those are the only differences between a 500 and a 590.


Timber Wolf
January 14, 2013, 08:39
I "extended" a Mossy 500 years ago with a new barrel, mag tube & spring sourced from Numrich. I bought two sets, one for me and one for a bud. Dumbass dyslexic UPS driver delivered them to lot 24 of the trailer park instead of my lot, 42, and threw the cardboard box under the steps. A couple of weeks later after it had rained the guy living in 24 spotted the box under his steps and brought it to me. The contents had started to rust so I called Numrich about replacements but they were out of them. I cleaned them up the best I could and gave my buddy the better set. Anyway, an 8 shot 500 is not a 590, they are different mag tubes and barrels, I think and maybe other things. I do not have a 590 so canít really speak to them. I do wish my long barrel had choke tubes, I may look into seeing if it can be threaded, it is pretty beefy.

January 14, 2013, 13:24
Yeah, I figured out about replacing the entire magazine tube. I got the 500 for $50 bucks, currently it has a 28 bbl, with screw in choke of some sort. So I figured" why not?".

January 14, 2013, 18:22
Brownell's sells a kit to do what you want to do. Includes the extended mag tube, barrel, spring, and runs about $150, on page 198 of the current catalog. Unscrewing the mag tube is pretty much a piece of cake, but I'd put some blue lock-tite on it when installing the new one, just because.
If you want more of the 590 stuff, you can buy the entire 590 trigger group with the metal housing for about $100 from Brownell's as well.
Hope this helps you out.


January 15, 2013, 13:11
Thanks guys! I think I will be building me a tac-to-cool shotgun shortly. Now to find enough rails to hang all the accessories on....LOL.