I bought some of those last year and used them a couple of times after pheasant and grouse hunting. I use B&P ammunition which uses a clean burning powder. So in my case it didn't do much.
If you use dirtier ammo such as Federal, it might be worthwhile.
The oil industry uses those in pipelines between loads of chemicals and oils. They are about 15 feet in diameter and are called “pigs”. They shoot them through with air to clean the pipelines..
Prep stock for your AR shotgun so when the zombie herd is overrunning your position and your going full semi auto to hold them off you pop one of those through every 31 rounds to clean the crud out
Ok back from the range with the product report: I do the same thing all the time - shoot 50 rounds at clays with one shotgun, then 50 slugs at steel with a different shotgun, then home to clean them both up using the same process of running three sets of cleaning patches [with solvent] thru the barrels, then oiling them and stowing them away for the next time.
This time last shot with each gun at the range was with the Cleanshot, after which only needed one pass with the cleaning patches [with solvent] to see that the barrels definitely were not as dirty. So I can say that if this product does no harm, for my limited use in my opinion it does something, but it doesn't do everything. I will buy them again just to have them as I tend to be lazy and pulling the trigger is more fun than boring, but in the future I can see where I will become frugal and forego the expense compared to a few patches with a few drops of solvent.
I've used them, they work well. They're especially nice to have around if you're like me and don't always get around to cleaning your gun right away. I prefer them for my single-barrel guns (autoloaders) vs SxS given the cost per barrel, but I can shoot several hundred rounds at the sporting clays course and trap range, pop one of these through at the end, and not worry about cleaning everything right away when I get home.
When we shooting a LOT of sporting clays, ONCE PER YEAR, I would scrub the bore with some shotgun solvent (different than rifle to deal with plastic fouling) and a SS tornado brush. Done.
By a LOT, we were shooting well over 10,000 rounds per year.