What does ACP stand for? On guns and ammunition it stands for Automatic Colt Pistol, the name attached to a family of pistol cartridges such as the .45 ACP and the .380 ACP. The letters tell you which cartridge design a box of ammunition or a pistol is made for.
Outside of firearms, ACP has a few other well known meanings. It can be the Affordable Connectivity Program, a past federal internet benefit, the American College of Physicians, or advance care planning in health care. The words around the letters usually make the meaning plain.
Quick facts
Stands for (firearms)
Automatic Colt PistolOther meanings
Affordable Connectivity Program; American College of Physicians; advance care planningType
Initialism, said A C PSeen on
Ammunition boxes, pistol barrels, benefit forms, medical chartsBest known example
.45 ACP, often called forty five ACPNot to be confused with
AP, armor piercing
What does ACP stand for in guns?
In firearms, ACP names a set of cartridges first made for semi-automatic pistols sold by the Colt company. The three words describe the original guns:
- A, Automatic: the pistols were self-loading, so each shot chambers the next round. Older ads called these automatics.
- C, Colt: the manufacturer that first sold pistols made for these rounds.
- P, Pistol: the cartridges are meant for handguns.
The number in front gives the caliber, roughly the bullet width in fractions of an inch. A .45 ACP bullet is about 0.45 inch across, and a .380 ACP bullet is smaller. Writing ACP after the number separates these rounds from other cartridges of a similar size that do not fit the same guns.
The .45 ACP and its relatives
The best known member of the family is the .45 ACP. It was designed by the gun inventor John Browning and was adopted by the US Army together with the M1911 pistol, named for the year it entered service. The pair stayed in military use for decades, which made .45 ACP one of the most familiar cartridge names in the country.
| Name on the box | How people say it | Notes |
|---|---|---|
| .45 ACP | Forty five ACP | Large pistol round, also called .45 Auto |
| .380 ACP | Three eighty | Smaller round used in compact pistols |
| .32 ACP | Thirty two ACP | Older, small pocket pistol round |
On an ammunition box: ".45 ACP, 230 grain." The first part says which pistols the rounds fit. Grain is a unit of bullet weight, not gunpowder. A shooter must match the box to the caliber stamped on the barrel.
ACP as a federal internet benefit
In news about home internet, ACP meant the Affordable Connectivity Program, a federal program run through the Federal Communications Commission. It gave eligible low income households a monthly discount on internet service, and in some cases on a laptop or tablet. The program stopped taking new sign-ups and later ended after its funding ran out, so older letters and websites that mention it may be out of date.
ACP in medicine
Health care uses the letters in two common ways:
- American College of Physicians: a large professional group for internal medicine doctors. You may see FACP after a doctor's name, meaning Fellow of the American College of Physicians.
- Advance care planning: talking through and writing down the medical care you would want if you could not speak for yourself. It often leads to a health care power of attorney or a living will.
Saying ACP and choosing the right meaning
However it is used, ACP is read as three letters, A C P. Put "an" in front, since A begins with a vowel sound: an ACP pistol, an ACP form. To pick the meaning, look at the clue words nearby.
- A number like .45 or .380 in front: Automatic Colt Pistol.
- Internet bill, discount or enrollment: Affordable Connectivity Program.
- Letters after a doctor's name: American College of Physicians.
- Living will, hospital forms or end of life wishes: advance care planning.
Browse the famous acronyms hub for more everyday letter groups.
Questions people ask
What does ACP stand for in 45 ACP?
It stands for Automatic Colt Pistol. The .45 part is the caliber, and ACP names the cartridge design first made for Colt semi-automatic pistols.
Is .45 ACP the same as .45 Auto?
Yes. .45 Auto is another common name for the same cartridge, and boxes may use either label.
Can I still sign up for the ACP internet discount?
No. The Affordable Connectivity Program ended after its funding ran out. Ask your internet provider about any low income plans it offers now.
What does FACP mean after a doctor's name?
It means Fellow of the American College of Physicians, an honor given to internal medicine doctors who meet the group's standards.
How do you pronounce ACP?
Say each letter: A C P. It is never pronounced as a single word.