I bought a Carlson's tube last year for my Mossberg 500.....Turkey .660, and rated for Hevi-Shot. I got it from the NWTF. A week later, the price doubled and now they aren't even carrying the Carlson's tubes.

I like the tube and it creates a nice, tight pattern at 40 yds and under. I also haven't tryed shooting further. I'm gonna give Hevi-Shot a try soon and see how it does.