The .45 Caliber
By .44 Magnum standards, the .45 ACP is not a powerful handgun cartridge. But when you compare it to the .380 Auto or the 9mm Luger, it's potent indeed. In practical-type shooting events there is often a power-factor limit that defines a minimum loading that can be used within particular rules. In any shooting event where recoil-recovery time is important, this usually means shooting the lightest "legal" load that will get the job done. It wouldn't be fair for someone to be competing with a .22 rimfire against a .40 S&W or a .45 ACP, hence the minimum power factor.
The power factor is usually computed by multiplying the bullet weight (grains) times velocity (fps). In many events the minimum number allowed is 120,000. This "power number" can actually be converted to horsepower if you divide it by 3,850,000.
To put the 120,000 number in perspective, it's like firing a 200-grain bullet at 600 fps. Another comparison would be a 148-grain bullet from a .38 Special at about 811 fps. Sometimes even higher power factor numbers are required by the rules of a specific event. In other events the power factor isn't specifically defined, but your gun/load combo has to be powerful enough to reliably knock down the targets. In these types of events you want to avoid loads that provide too much power as they will handicap your performance. The .45 ACP loads I have listed here are designed to be on the mild side. And this brings up a potential problem Semi-autos require a minimum power level to function properly. Individual guns may have less friction and/or softer main recoil springs, so it's not possible to make a general statement on how much power is needed for your particular gun. You can even change your power requirements by using different lubricants or changing springs. The only way to handle all these variables is to pick a load and make up a small number to try. If your gun works well with them, you can make up a larger patch for a more complete test. If you get failures to feed or weak ejection, you'll need to adjust your loads--a matter of trial and error.
When using light loads you can easily run into a situation where the powder charge is so small in volume there's room in the case for two or even three charges. That's a real risk and it's generally better to find a more bulky powder or a slower alternative that requires more weight (and therefore more volume) of powder to get the job done. The accompanying table is arranged to show what powder charges are needed for three specific velocities. For each bullet weight the loads use a relatively fast, relatively slow, and an in-between powder. But since function and accuracy are the important factors here, you may have to try several different powders and loads to get what you want.
There's still another powder characteristic to consider. Certain powders--particularly pistol and shotgun types--are touted as "clean burning." These are good only if they produce better scores for you. If they don't, then "clean" has no advantage. And in competition--as long as you're firing legal and safe loads--score isn't merely important, it's everything.
The .45 ACP is such a popular round that everything you need is going
to be easy to find. For this month's loads, I used lead bullets. At the
velocities shown here, bullet lubrication isn't particularly important.
At velocities below about 1,000 fps, almost any kind of lubrication
will do. In fact, many guns can even shoot unlubricated bullets at these
velocities without leading (this seems to be a function of the internal
barrel finish).
