These darn things tend to move around, especially when the gun is fired. This is not desireable.
The best "butt cuffs" are a form-fitted, lace-up leather or heavy cloth sleeve. It wont move. Someone has to make this one.
Next best is a factory one, to which you add a strap over the buttplate to keep the whole thing from sliding forward to the trigger.
In the case of a "pure factory type", you would almost be better off cutting the cuff "tube" open and adding a velcro "zipper". Keep it with the gun, and when you grab the gun, move the cuff to the belt or to the offhand forearm. Note that most folks do not sleep with a belt on.
If you merely want a cuff so you have five to load the gun, then strip the thing off the end of the buttstock as soon as you are done loading.
I have found a really handy (and cheap) way to have "ready ammo" for a shotgun. I have used the cloth bag that comes with every 100-round box of (belted 7.62) M-60 Machinegun ammo. These little bags-on-a-strap are just right for holding an entire 25 round box of shotgun shells. They sling over a sholder easily.
Nothing is more "tacticool" than mil-surplus OD green cheapo cloth sewn, by blind people, into something useful for the US Military.
You can easily make these things. Get some heavy denim or canvas. Sew a sturdy square-bottom pouch that loosely fits a box of shotgun shells. Sew a reinforcing strap around the opening. Sew a sholder strap into a loop, then stitch the loop to the narrow sides and bottom of the bag, so the strap loop is under the bag. You now have an insustrial strength ammo bag for the burglar-repellant gun. You can dump the shells in loose, or remove the box top and put the whole box in.