• Mossberg Owners is in the process of upgrading the software. Please bear with us while we transition to the new look and new upgraded software.

20g SW add a rifle sighted slug barrel


I wish to convert my 20g SW to slug gun for my son. The barrel nut looks different on 500s as compared to SW barrel nut. Does anyone know of a (18” or 20” preferably) rifle sighted barrel that will work.


That is a 590-based gun so the nut IS different as are the barrels and mag tubes. Everything else is "the same"...

Keep in mind there may be NFA "rules" regarding converting an SW into a full-length gun. There are tax-stamp holders that will be by to clarify the rules, I'm sure.


Bobster provided you the correct answers regarding Shockwave configuration.

Guess I'm confused regarding the desired barrel. If you're after a true "rifled" barrrel think you're better off buying a standard 500.

That said, you can certainly shoot slugs from your existing shockwave barrel and it can be configured with rifle sights.

Only difference is the slugs themselves.



Just a smooth bore barrel with rifle sights. 18” or 20” would be perfect. I have a hogue youth stock just need a barrel for conversion. If new guns were readily available is would buy what I needed. No need to chime in, I know I cant attach the stock until I have the 18” + barrel installed.

John A.

Unconstitutional laws are not laws.
Staff member
Global Moderator
As far as NFA goes, scj3081 is correct. He can convert it to a "shotgun" if he prefers.

It's just unlawful to start with a shotgun and go backwards and put a grip on and then a shorter barrel, which is idiotic, but I don't think anyone ever said the government did anything that ever made sense.

With that said, as Ernst mentioned, you can use a smoothbore barrel with slugs no problem. And I'm even looking for a hogue stock in fde for one of my 500's. But I don't know if there is a such thing as an 18 inch 20 gauge 590 barrel. I don't recall ever seeing or hearing of one.

They do make 500C mossbergs in 20 gauge, but as you have noted, the magazine is different, unless you want to change it out to a 500c magazine tube along with the barrel may work.