Quoted:
thanx dfaris - so if I understand correctly, only the 18" barrels are available in the 870Express chassis? what is the highest capacity I can go with the 18" barrel?
I did check out the civilian Rem website and just could not find a 20" barrel option that was a smooth bore and without the vent ribs....
An 18" gun will accept a +2 extension. A 20" will accept a +3 extension. These will be even with the muzzle.
In the Express, Tactical, and Magnum Marine, 18" barrels are the longest offered.
Actually, most of these are now 18 1/2" barrels.
The Remington factory extension projected past the muzzle of 18" barrels by 3/4" because it was intended to act as a mounting point for a bayonet for military use.
Within the last few years Remington changed the 18" barrels to 18 1/2" on most guns so the extension is now even with the muzzle.
Remington does sell 20" police type barrels and you could sell the barrel that comes on the gun you buy and replace it with a 20".
For a standard 20" barrel you have to step up to the 870P Police models, They cost more and are a little harder to get, but it's the top of the line in 870 defense guns.
It's smoother inside and out, has a tough parkerized finish that's 60% more durable then bluing, and is built to a higher standard.
If you want a good gun that will last more than your lifetime, the Express based guns will do just fine.
If you want the best there is Cadillac version, the Police models are it.