Wayne, I have put them in shotguns and they work fairly well. The heater hose is. like you said, to take up space IN FRONT of the tube and a little in back of it as well to keep it from moving around.
I would put a muzzle brake on anything that big. They have some which will act as a sound attenuating device as well. Most shooters bitch about the sound of muzzle brakes but I shoot or have shot the big mothers, ie, 30/348. 300 Wby., etc. and the only device which will work well is a good muzzle brake. You can put a couple of pounds of shot in the stock which will further cut the recoil. The mercury filled tubes are just weight which moves. They work of the principle of "an object at rest tends to stay at rest." There are a couple of plastics/composition recoil pads which cushion recoil but don't reduce it. They just make it easier for your shoulder to remain red rather than purple.
Doc