CE Harris wrote an article just on this. It is a long document covering several types of shot shells for handguns. Here is the part on the 45 ACP
In the early 1970s, while serving in the military, I developed a
handloaded .45 ACP shot cartridge which was used by friends as an
aircrew surevival load. It could be mixed interchangeably in a
magazine with Ball ammunition, which would feed and operate the
pistol semi-automatically. I refined the load later and
described it in American Rifleman, April, 1976 p.20. This
article is also reprinted in the NRA booklet on The .45
Automatic.
These .45 Shot shell cases are made from .308 Winchester or 7.62
NATO cases, by using an extended shell holder to push lubricated
cases into the forming die, which are cut off with a fine-toothed
hacksaw, filed flush, and inside deburred while in the die. Use
of .30-'06 cases or others with a narrow extraction groove may
cause extractor breakage. Cases should NOT be annealed because
the extractor may tear through the rim, due to the mouth
obturating into the rifling upon firing.
To prepare cases for loading they are outside deburred, full-
length sized, primed, and flared slightly. The recommended
starting powder charge is 6.2 grs. of WW231. No changes powder
substitutions or changes other than minor adjustments to obtain
reliable functioning, are recommended. This exact powder charge
is gun specific as not all will function reliably with the same
charge. This load functions most reliably in slightly worn bores
which do not have a sharp origin of the rifling. Start with the
suggested charge and load just a magazine full to try. If they
cycle, great. If they don't, examine the fired cases.
A too heavy charge causes the case to obturate into the rifling,
causing stovepipes from hard extraction. This is the hardest to
convince reloaders of -- everyone thinks the more powder, the
better the extraction -- it AIN'T always so! If you can see
distinct rifling marks on the case, particularly if accompanied
by rim distortion, reduce the charge 0.3 grain and things will
work better. If you get jams from short recoil (most jams in
this load will be stovepipes regardless of whether too little or
too much powder) there are NO marks on the mouth of the case.
That means the charge is too light, so increase it 0.3 grain. If
the powder load is JUST right, you should have very light rifling
marks on the case mouth, with no obvious rim distortion and the
gun will cycle with near perfection.
The only correct wad to use is the Remington SP410 shot cup used
for 1/2 oz. .410 bore skeet loads. Others do not fit properly in
the cut-off rifle brass. Seat the wad firmly over the powder
charge using a 3/8" dowel and a few light blows with a plastic
mallet. Then trim the protruding wad tabs off flush with the
case mouth using a sharp knife. The case holds about 105 +/- 5
grains of No.8 or #9 shot.
Good results can be had using .35 cal. gas checks for the top
wad. Just fill the case and shot cup full to 1/16" below the
case mouth and place the gascheck cup down on the top of the
load. The gascheck will find its way to the right place and the
case will crimp onto it giving a finished shell with a nice
appearance.
Typical velocity is 1200 f.p.s. in the M1911A1 pistol and
patterns average 70% in a 15" circle at 25 feet. This produces
10 pellet hits in a 5" diameter target, simulating a small game
animal, and defines the maximum effective range for this load on
snakes or small game. A good handgun shot can break clay birds
from stations 1, 7 or 8 on a skeet field fairly easily. I have
found with No. 8 shot they are sure killers on cottontails to 10
yards. I don't recommend shot larger than No. 8 as the patterns
are too thin. The .45s pattern about as well as ordinary .44
Magnum shot shells (not the longer "Hot Shot") in a Thompson
Contender with choke tube, but you have a 7-shot semi-auto!
The dies for forming the cases and reloading this .45 ACP shot
shells are available from RCBS, but are a bit pricey. Remington
and CCI both offer factory loaded .45 ACP shot shells for
occasional users who can't justify the expenditure of time and
money to set up and make their own.
To sum up, any outdoorsman who carries a handgun afield on a
routine basis needs a few shot loads occasionally. Whether you
handload them or buy them, get a few. I don't use all that many,
maybe a half-dozen a year, but when I get surprised by a
copperhead or rattler in the woodpile or outhouse, they are sure
comforting! And then, there's always a chance that a grouse may
appear under my tree stand during deer season...
