The Best Remington 870 Magazine Extension
There are many magazine extensions available on the market today. New extensions are introduced regularly. I have tested many of them myself, some of them were tested by readers of the Rem870.com blog.
The best magazine extension is the one that fits your shotgun perfectly. Some people like when mag extension is flush with a barrel, some like when extension is little longer than a barrel.
Here is list of the reviews of the magazine extensions for Remington 870, so you can find the best one: