45 Automatic (45 Auto) is SAAMI's recognized name for the .45 ACP cartridge developed around John Browning and Colt's early self-loading pistol work and adopted by the U.S. Army with the Model 1911 pistol. This relationship-only page covers the cartridge as a standardized handgun and submachine-gun round, with SAAMI and C.I.P. dimensions, U.S. military ball-cartridge context, current commercial loads, and a sourced compatibility link to the Glock 21 family.
SAAMI treats standard-pressure 45 Automatic, 45 Automatic +P, and 45 Automatic Match as separate standardized names inside the same 45 Auto family, while current commercial listings mainly distinguish loads by bullet construction, grain weight, velocity, and training or defensive use.
| Variant | Configuration | Designation notes |
|---|---|---|
| 45 Automatic | Standard-pressure 45 Auto cartridge | SAAMI lists 45 Automatic with the abbreviated name 45 Auto and publishes the shared 45 Automatic / 45 Automatic +P cartridge-and-chamber drawing. Sources: SAAMI Z299.3-2022 |
| 45 Automatic +P | Higher-pressure SAAMI variant | SAAMI lists 45 Automatic +P as 45 Auto +P and warns +P ammunition is loaded to higher pressure for firearms specifically designed and recommended for it. Sources: SAAMI Z299.3-2022 |
| 45 Automatic Match | Match-standardized designation | SAAMI separately lists 45 Automatic Match / 45 Auto Match and publishes a distinct match cartridge-and-chamber drawing. Sources: SAAMI Z299.3-2022 |
| 230-grain FMJ commercial loads | Training and range ammunition | Federal's American Eagle 45 Auto load uses a 230-grain full metal jacket bullet at 890 fps from a 5-inch test barrel, and Winchester sells a 45 Automatic 230-grain full metal jacket range load. Sources: American Eagle Handgun 45 Auto, USA45AVP | Winchester Ammunition |
| Caliber .45 Ball M1911 | U.S. military ball cartridge | Army ammunition data sheets list Ball M1911 for the M3A1 submachine gun and M1911A1 pistol, with a 1.275-inch cartridge length and 885 +/- 25 fps velocity at 25.5 feet. |
| Caliber .45 Tracer M26 | U.S. military tracer cartridge | Army ammunition data sheets list Tracer M26 as a caliber .45 cartridge for M3A1 and M1911A1 use, identified with a red bullet tip. |
| Caliber .45 Blank M9 and Dummy M1921 | Training and non-ball military cartridges | Army ammunition data sheets document blank and dummy .45 cartridge types alongside ball, match, tracer, high-pressure test, wadcutter, and line-throwing entries. |
The catalog currently has one specific .45 Auto firing-weapon record that can be linked directly: Glock's full-size G21 family.
| Compatible item | Item type | Compatibility evidence |
|---|---|---|
 | Semi-automatic pistol | GLOCK lists the G21 SF, G21 Gen4, and G21 Gen5 MOS as .45 Auto pistols, and SAAMI identifies 45 Automatic (45 Auto) as the recognized cartridge name. Sources: SAAMI FAQs, GLOCK 21 SF, GLOCK 21 Gen4, GLOCK 21 Gen5 MOS |
45 Auto sits at the overlap of early U.S. military pistol ammunition and modern commercial handgun ammunition. SAAMI supplies the U.S. voluntary standard for 45 Automatic, 45 Automatic +P, and 45 Automatic Match; C.I.P. publishes the 45 Auto tabulation with 45 ACP as an alternative name; current manufacturers continue to list 230-grain FMJ range loads and hollow-point defensive loads.
SAAMI's recognized full and abbreviated names are 45 Automatic and 45 Auto. C.I.P. lists 45 Auto and gives 45 ACP as an alternative name.
Sources: SAAMI FAQs; SAAMI Z299.3-2022; C.I.P. 45 Auto TAB. IV.
SAAMI lists 21,000 psi maximum average pressure for 45 Automatic, while C.I.P. lists 1300 bar Pmax for 45 Auto.
Sources: SAAMI Z299.3-2022; C.I.P. 45 Auto TAB. IV.
Federal lists 230-grain 45 Auto FMJ at 890 fps in American Eagle, 230-grain Punch JHP at 890 fps, and 210-grain Hydra-Shok Deep JHP at 980 fps; Winchester lists a 45 Automatic 230-grain FMJ USA range load.
Sources: American Eagle Handgun 45 Auto; Shop products in 45 Auto today | Federal Premium; USA45AVP | Winchester Ammunition.
American Rifleman traces the cartridge's development through Colt and John Browning's early self-loading pistol work after the U.S. Ordnance Department specified a .45-caliber cartridge.
Sources: The .45 ACP: History & Performance
NRA Museums identifies the Colt Model 1905 as a .45 Rimless automatic pistol and describes the cartridge as the pistol's distinctive feature during the trials lineage that led to the Model 1911.
Sources: Colt Model 1905 45 Automatic Pistol
The Colt Model 1911 pistol and the Cal. 45 Automatic Pistol Ball Cartridge, Model of 1911 were formally adopted by the U.S. Army.
Sources: The .45 ACP: History & Performance
SAAMI's 2022 centerfire pistol and revolver standard lists the 45 Automatic / 45 Automatic +P cartridge-and-chamber drawing as originally issued on May 29, 1979.
Sources: SAAMI Z299.3-2022
TM 43-0001-27 lists caliber .45 ball, match, tracer, blank, dummy, high-pressure test, wadcutter, and line-throwing cartridges in the Army small-caliber ammunition data sheets.
Sources: TM 43-0001-27 Small Caliber Ammunition
C.I.P.'s 45 Auto tabulation lists the United States as country of origin, 45 ACP as an alternative name, and a 2020 revision date.
Sources: C.I.P. 45 Auto TAB. IV
