During WWII the British Isles were under credible threat of invasion by the Axis forces particularly in the early years of that war.
Local Defence Volunteers -- name later changed to Home Guard -- were men who had been rejected for active military service, but who were tasked with providing defence for England while the active military was busy elsewhere.
A great deal of the time, the LDV were armed with only what they could bring from home, and even in those days, the only thing most of them had that would go "Bang!" was a two-barrel fowling piece.
And most of the ammunition readily available for the shotguns was light shot -- unfortunately what is good medicine for grouse at fifteen yards might tend to put you closer to an errant Fallschirmjager than one might like.
The solution was called a "ringer" in England, and a "cut-load" in the United States, and was an old poachers trick to turn the paper-hulled shot shells and side-by-side shotgun into a nasty medium-range thumper.
The execution was simple: the old paper-hulled shotgun shells generally had two thick felt wads between the powder and the shot column. One simply made a spiral cut through the paper hull of the shell at a location between the two wads -- making sure that the cut overlapped, and that the ending of the cut was about an eighth to a quarter of an inch below the beginning of the cut.
When a normal shell was fired in a shotgun, the hull remained attached to the base and the end opened up to allow the shot to fly down-range in a cloud.
In one that had been modified into a "ringer" or "cut-load", this would not happen. Instead, the hull would separate from the base and the entire paper hull -- shot and all -- would exit the muzzle in one solid mass. The shot would not leave the hull until it came into contact with a deer -- or a German paratrooper.
It was -- more or less -- a giant paper 12-bore Glaser safety slug.
Old Africa hands going into the bush hunting birds would slip a couple of "cut-loads" into their pocket in case something with teeth tried to get up under their hat with them as they were potting birds for the evening meal, but I really thought that the practice of "ringing" had died out with the paper-hulled case, and that it wasn't really possible with modern plastic-hulled cases and modern pressures.
Turns out that I was wrong:
Just because some tricks are old, doesn't mean they're not effective.
Folks, two things cannot be cautioned enough: if you use cut-loads, feed the cut-load directly into the chamber by hand. If you try to put cut-loads into a tube magazine eventually they will come apart and dump powder, shot and other nastiness into your shotgun's innards; and
Check local laws. This is an old poacher's trick and well-schooled game wardens may look askance at finding you on the dove field with a pocket full of shells modified for deer-whacking.