Your going to need a plus one for here and a plus what ever you want for America, I think I got a plus 5 or 6, cant remember. It's about 2 inches past my choke tube. You want it longer than your barrel to protect your barrel and front sight from garbage in the bottom of the dump cans.
I got the big one with nut, spring and cap from MOA then later I got the plus one and extra spring from here https://cpwsa.com/products/nordic-components-products-nordic-mag-tube
MOA might have both though. Also some guys are using the plus one with the stock spring but it's always good to keep extra springs so...