The "true" 18" barrels are from (or used to be) 870P guns exclusively. That's why they're (generally) more expensive.

Up to you on what you do with it, but the detent or lack thereof has never stopped me from using a particular barrel.

 

I have not heard of there being a ball bearing in any of the barrels. What are they for, and where are they located?
Other than that, I don't see much difference in .5" in a real tactical sort of situation.

 

does that mean most general smooth bore 12 ga. 870 express shotguns like the ones sold at Big 5 are 18.5, not 18?

 

All of the new 870 shotguns have 18.5" barrels now. The extra 1/2" means a lot because now they are capable of 7+1 capacity with a after market tube extension that is even with the muzzle. Not the factory tube extension because it limits the capacity to 6+1.

Remington still has in their specs and advertises a 18" bbl but they measure from close bolt to muzzle 18.5 inches.

GC

 

I have not heard of there being a ball bearing in any of the barrels. What are they for, and where are they located?

Old style "Wingmaster/Police" vs. new style "Express" magazine cap retention. The old-style has a spring loaded detent ball that engages small divots on the outside of the cap. The express style has a spring cap that has teeth that engage a matching set of teeth on the interior of the mag cap.

Other than that, I don't see much difference in .5" in a real tactical sort of situation.

There isn't, really.

All of the new 870 shotguns have 18.5" barrels now.

Did not know that. I love this place.

 

All of the new 870 shotguns have 18.5" barrels now. The extra 1/2" means a lot because now they are capable of 7+1 capacity with a after market tube extension that is even with the muzzle. Not the factory tube extension because it limits the capacity to 6+1.

Remington still has in their specs and advertises a 18" bbl but they measure from close bolt to muzzle 18.5 inches.

GC

I know that you say you dont need a mag clamp but thats the only thing holding me back from buying your extension, I personally prefer a mag clamp. That and the fact I would now need to buy a 18.5" barrel

 

The express style has a spring cap that has teeth that engage a matching set of teeth on the interior of the mag cap.

The 870 Express HD shotguns that come with a factory mag tube extension have the detent ball and no mag tube dimples.

I know that you say you don't need a mag clamp but thats the only thing holding me back from buying your extension, I personally prefer a mag clamp. That and the fact I would now need to buy a 18.5" barrel

There some good after market clamps available. I see no reason to hold onto a 18" bbl. when the 18.5" allows 7+1 capacity.

When I was planning on have two Excell Auto 5 bbls cut to 20" my thought was why not go to 20.5" and have 8+1 capacity with a tube extension that is even with the muzzle. So that is the way I went.

1/2" added bbl length makes very little difference in how the gun looks and handles but it can make a big difference in how many rounds the mag tube can hold.

GC