Donald, A 590 is a dedicated riot/security platforms and only has 18 and 20 inch barrels available. If you're looking for something that can go beyond 20 inches you need to be looking at a 500. The 500 and 590 are closely related but are not quite the same: the 590 uses different barrels and magazine tubes from the 500. Or you could just go for this combo >>> budsgunshop.com/product_info.php/products_id/34511/mossberg+&+sons+88+fieldsecurity+combo+12+ga+28+&+185+barrel ....Have a great day!

The 590 is only available with a 20-inch (510 mm) barrel and flush-fit magazine tube. The 590A1 is available with a 14-inch (36 cm), 18.5-inch, or 20-inch (510 mm) barrel.

Donald, yes and no. The 590 is a 500 with an extended mag tube and barrel that attaches to it's end. You would need a 500 mag tube to use 500 barrels. I would just go with a Model 500/Maverick 88 to have the best assortments of different barrel lengths. budsgunshop.com/product_info.php/products_id/34511/mossberg+&+sons+88+fieldsecurity+combo+12+ga+28+&+185+barrel