A charge of shot flying 25 yards through the air has the wind resistence of individual pellets, with considerable loss of velocity, impact energy and pentration by 25 yards. By 210 feet individual birdshot pellets will not penetrate denim, but buckshot will and slugs will definitely.
A cut shell end flying 25 yards through the air intact has the wind resistence of a solid slug, retaining a greater percentage of velocity, energy, penetration than individual pellets would.
Videos of cut birdshot shell experiments show round entrance holes on targets at 25 and 50 yards. Cut traditionally, the cut shell has a heavy shot end and a light wadding end and stabilizes as a badminton birdie does.
The wound effect of a cut birdshot charge at 25 yards would be like a birdshot charge at near contact range, not at all like a shot charge spread at 25 yards.
The Atlas of Forensic Pathology by the Chicago medical examiner has autopsy photos of contact range birdshot wounds; the people who received those wounds were on the autopsy table, obviously dead. The wound channel (for 12ga) was 3/4 inch wide about 6 inches deep with the shot scattered about 4 to 8 inches deep.
Nancy L. Jones, "Atlas of Forensic Pathology", Igakou-Shoin Medical, 1996.
NLJones shows autopsy photos of fatal wounds from birdshot.
_ A "contact" shotgun wound with muzzle abrasion effects. "The entrance wound is the same size as the bore of the shotgun." And same appearance as the wounds from rifled slug at any distance (except for the muzzle effects).
_ A "very-close-range" shotgun wound that shows abrasion by the wadding on the edge of the hole. The wadding entered the round hole wound with the shot. There was gunpowder particle stippling about the wound.
_ A "close range" shotgun wound that shows a square abrasion just above the main wound by the plastic shot cup striking the skin before following the shot charge into the wound. The hole had a "scalloped" edge where the shot started to spread, only one pellet struck seperately.
_ An "intermediate range" shotgun wound with a large main hole and several surrounding seperate pellet wounds.
_ A "distant" shotgun wound with seperate pellet wounds in a pattern of at least 18 inches spread.*
These were cases of birdshot being used to put people on an autopsy table before a medical examiner. Since it was a forensic pathology book, whether the homicides were in defense or offense was not discussed. I suspect the deceased would have wished birdshot was next to useless for defense or offense.
Birdshot is not the first choice for a combat round but it is not a near useless munition at home defense distances either.**
I will admit that use of the cut birdshot shell is a useful skill to know, but only for emergency use. I would not hesitate to make cut birdshot in a "stranded on the mountain in Bear Hollow" or other survival situation. The effects of cut birdshot shells in practice against barndoors, etc., did give the WWII British Home Guard some confidence in carrying their fowling pieces on coast watch duty.
For home defense I will chose coarse goose or turkey loads (swan drops) or 00 buck shot and leave the birdshot for busting clay pigeons. In the time I could spend preparing cut shells at home I could go out and buy regular hunting buckshot or slugs - box of five is not that expense.
I also believe that a lot of military/police buckshot is of the reduced recoil variety while hunting buckshot tends to be loaded for bear.
Even though I have tried cut shells, I have some reservations about its use beyond YouTube demos of what they did in the past. I suspect that deer were scarce around here in the 1950s because in the 1930s Depression and WWII meat ration eras farm families would use the cut shell trick to put deer meat on the table. I also believe that if a game warden caught me outdoors with birdshot altered to single projectile, I would have some 'splaining to do. There's too long a history of it used to poach deer during squirrel season.
In a self defense situation, an over-zealous prosecutor could cite possession/use of altered birdshot as proof of malice or depraved mind if he's in an "indict a ham sandwich" mood. Some jurors might ask themselves "why wasn't ordinary ammo good enough?" on their own without prompting.
As the radio editorialist used sign off, just before the "Sleepy Joe" program came on, "I ask not that you agree with me, only that you think about it.
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* ("Close" to "intermediate" means the clothing or skin of the victim should show gunshot residue, soot or gunpowder particles. "Distant" means the shot was far enough away there would be no stippling and no gunshot residue on the victim's skin or clothing.)
** I don't want to spread the idea birdshot is a less lethal munition either. NLJones noted also that birdshot pellets may enter a vein or artery and get circulated until they block an artery. The victim could be shot in the leg and die of a heart attack or stroke caused by a pellet circulating until it clogged an artery in the heart, neck or brain. That is too slo-mo to depend on for defense, but it also emphasizes the point you should shoot to wound only when lethal force is justified.