Who makes the best one? And I am thinking on terms of more bang for my buck. No more than $30. (so mesa tactical isn't on the list....yet)
Oh, and it would be on a Mossberg 590A1
Tank's Rifle Shop sells a very close copy of the Remington factory clamp, which is one of the best.
The Tank's clamp is available with or without the bottom swivel stud and with or without the swivels,
These are actually made by Uncle Mike's, but they no longer show it on their web site: