The first mistake you made is using Remington buckshot. Patternmaster's claims are with Federal buckshot. The difference is that Remington does not use a shot sleeve in their buckshot and Federal does. The Patternmaster choke fuctions by delaying the plastic shot sleeve so the shot can exit the barrel undisturbed. There are a few other aftermarket chokes that use the same technology (Kick's, Rhino). I have a Patternmaster choke tube on my Rem. 1187 SM and Beretta A390. It is the ONLY choke I use for Buckshot, Steel Shot, and Turkey loads. I dropped a Turkey last year at 40 yds in the woods. It didn't move an inch. Also, make sure you get the appropriate size. I have a 3.5 inch model for the Rem. and the standard size for the Beretta.
You cannot use any type of load that employs special or no shot sleeve (like flitecontrol). These things just interfere or do not allow the Pattermaster to fuction properly. Go to the Patternmaster website and learn about the choke some more.