[Jerryboy]

looking for an extended mag tube for a Westernfield 550ADB 12g.

and how to install it if i find one.

 

[Bindernut]

The Western Field 550 is a store brand version of the Mossberg 500, so pretty much any accessories for the Mossberg 500 will fit on your shotgun.
Unfortunately the way that the barrel attaches to the magazine tube means that you'll need to go with a complete new mag tube and barrel to get any extra magazine capacity.

 

[Snakedriver]

The Western Field 550 is a store brand version of the Mossberg 500, so pretty much any accessories for the Mossberg 500 will fit on your shotgun.
Unfortunately the way that the barrel attaches to the magazine tube means that you'll need to go with a complete new mag tube and barrel to get any extra magazine capacity.

Correct and unfortunately, this is the reason the Mossberg 500 is a less popular HD gun than the Remington 870. I have both set-up for HD duty, but I'm not really too concerned. The 870 with a +2 mag. extension gives me 6+1, but 500 in its standard configuration is 5+1. The one round differential is not so great that I can't deal with it.

Mossberg 500 on top:

 

[Jerryboy]

ok thanks for the info, i guess i'll just have to go with a shorter barrel instead of an extended mag cap and add both an elastic buttstock shell holder as well as a side saddle.