If you follow 3 gun you already know that the ability to load a shotgun fast is a skill that sets the winners apart from the losers. In larger matches, or on an all shotgun stage, you may have to load up to 30 rounds in your shotgun on one stage. If it takes you 10 seconds to load 8 rounds in your shotgun, but takes your competitor only 4 seconds to load 8 rounds, then on a stage where you have to load 24 rounds, you lose by 18 seconds, even if you shoot the targets at the same speed. This is why shotgun loading is so important.
I first saw the Bennie Cooley Sniper Assault Mount (BC-SAM) in action when I shot on the same squad as Bennie Cooley at the MGM Ironman. At first glance, the mount looks like many of the other AR style one-piece scope mounts. However, in function, it is unlike anything else available and is probably the most advanced and well-designed AR mount in the world.
My favorite AR-15 3 gun stock is the Magpul PRS because it’s adjustable. I can have it fit me close to perfectly. The downsides are that it is heavy and I don’t like the sling attachment setup the way it comes from Magpul. Every once in a while during a 3 gun match its necessary to use a sling. I like QD (Quick Detach) sling mounts because they are fast, reliable, and are flush fitting. There is now a product that will allow conversion of the Magpul PRS sling system to QD. 
With 3 Gun season quickly approaching it is time to start practicing loading the shotgun. During a match, shotguns can be unloaded as fast as you can pull the trigger but loading them is a one shell at a time process. Practicing your loading technique can make a big difference in your overall time and score. Remington is now making Dummy Shotgun Shells that are to factory spec and have real shot in them so they feel the same as loading a live round.