I’m not sure about one letter you posted on February 10th. While I have no direct experience with them it is my understanding that the conversion for the [Mossberg 500] Knox drum and magazines do not allow the use of the gun’s original magazine tube. Thus, the Sidesaddle and shell carrier on the butt COULD be used to “combat load” through the ejection port with the Knox drum/mag conversion [in place] but otherwise it only adds weight to the gun. The conversion (I believe) only allows feeding from the box mag/drum). Hopefully someone with hands-on experience will be able to confirm or refute my understanding of things.
I can comment on the recoil reduction from their pistol grip stock, one of our customers had one for a short time and I did try it a few times. When used as most of us have been trained, firmly pull the butt into the shoulder, it does little to reduce felt recoil. The trick is too hold it loosely against the shoulder to allow the recoil reducing device in the pistol grip to do it’s thing. I think if it requires a different grip and mount on the gun the same thing (reducing recoil) can be done without shelling out the cash for a fancy stock. I don’t know who first started pushing the new shooting style for shotgun but it works, let me try to explain:
Shoulder the gun as you would normally but don’t pull hard into the shoulder as we all have been told for all these years, only use the force needed to keep the butt in place. Use your support hand to pull forward and use it to absorb recoil. Don’t lock the support arm out, allow it to flex some at the elbow and let your support arm function as a shock absorber. You can even use this in close quarters by allowing the stock to ride over your arm/shoulder and rotate the gun a bit inboard (counterclockwise for the right handed shooter). This allows the muzzle to come back as much as 5 inches in my limited experience. The key to all this is to pull the gun forward against the force of recoil. It is especially useful on short, pistol gripped breaching guns (the only real use for a pistol gripped shotgun, as I see it) as it keeps the recoil from pounding against the web of the shooting hand. If my shoddy explanation makes sense to you, take the wife and kids out and try a box or three and you will see a difference, I have had good results with some timid and recoil sensitive shooters. – Jake at The Armory