870 21" bbl Sumtoy and Magblends?

[IowaGobblers]

Anybody shooting this combo?  I have some feds. that should last me long enough but I have the chance to pick up some magnlends really cheap and want to know if they shoot well. Thanks

[surehuntsalot]

tried the magblends through a .570 Hastings and a .570 Tightwad
great patterns with both
something around a .570 should do fine

[owlhoot]

sure didn't like my 21" rem 20 with a RSF .572 i believe.  No ports. very open pattern.

let us know what you get, please and thanks.