870 barrel lengths and mag tube extensions

[Mooseman]

Am I correct that you can only fit a 2 shot mag tube extension on an 18.5" barrel? What barrel length would you need to fit a 3 shot extension?

 

[AcceptableUserName]

20"............

 

[dfariswheel]

For 18" you use a +2.
For a 20" use a +3.

You "Can" put longer extensions on that project well past the muzzle like some 3 gun shooters do.
The only that that happens is that the extension gets fouled from the gasses.

The hazard is, its a lot easier to knock the extension off if you bump it.

 

[76shuvlinoff]

I have a 2 on my 20, yep probably could've gone to a 3 easy.

 

[AndyJ]

A Remington +2 will extend past the end of an 18" barrel. A Choate +2 is even.

A Remington +2 will be even with an 18.5" barrel

 

[meytind]

A member named MAX100 makes a +3 extension that fits flush to 18.5" barrels. The reason the Remington brand extensions don't is because of the little crimped part where the mag clamp attaches and because of the smaller front part.

 

[dfariswheel]

The smaller cap on the Remington factory extension was originally intended to be the mounting point for a bayonet.
That's why it sticks out beyond the muzzle slightly.

For some reason, Remington never saw a need to change the design.