Practice & target
Full-metal-jacket, plated, lead, and wadcutter bullets describe different constructions. Grain weight is projectile mass; it does not state a powder charge or guarantee recoil.
THE CARTRIDGE LIBRARY · PISTOL
.45 GAP
GAP stands for Glock Automatic Pistol. This is a distinct, shorter-case .45-caliber semiautomatic-pistol cartridge, rather than another name for .45 ACP.
2A Ledger reference desk · Sources checked October 18, 2026
Read the dimensions
- Overall · min–max
- 1.055–1.137 in
26.797–28.880 mm - Case length · max
- 0.760 in
19.304 mm - Bullet maximum
- 0.452 in
11.481 mm - Rim diameter · max
- 0.470 in
11.938 mm
Know the exact name
At a glance
- Cartridge family
- Pistol
- Bullet specification
- 0.4520 in / 11.481 mmBullet maximum
- Factory examples
- 2 loadsSelected, sourced examples below
- Weight in cited examples
- 230 grGrains measure mass, not powder charge
.45 GAP is identified by its complete cartridge designation. The resource-table alternative is 45 Glock Automatic Pistol. A caliber number, bullet diameter, or family resemblance on its own does not identify ammunition compatibility.
.45 GAP and .45 ACP are separate chamberings despite similar bullet diameters.
Dimensions: open the exact dimensional drawing ↗. The displayed number is bullet maximum, rather than an assertion that every manufactured projectile or barrel has this exact diameter.
Origins & evolution
Background & development
GLOCK introduced the .45 GAP in 2003 with the G37 pistol. The initials mean GLOCK Auto Pistol. The project sought .45-caliber performance in a shorter cartridge that would fit a more compact grip envelope than GLOCK’s existing large-frame .45 Auto pistols. It was the first commercially introduced cartridge to carry the GLOCK name.
That goal reflected an important handgun-design problem of the period: combining a large bullet with a double-column magazine could produce a grip too large for some users. The GAP approached the issue through ammunition dimensions as well as firearm design. GLOCK subsequently offered the G38 and G39 in the same cartridge family. It did not displace the far more established .45 ACP, but its history remains a useful example of a cartridge created around ergonomics and a specific pistol platform rather than around a new bullet diameter or a claim to maximum power.
Historical sources: American Rifleman: GLOCK development history and 2003 GAP introduction ↗ · GLOCK: official cartridge-family description ↗
Construction changes the story
Loads, variations & specialty offerings
Expanding factory bullets
JHP, XTP, FTX, HST, and similar product names refer to particular designs. Muzzle energy alone does not show expansion, penetration, or reliability in a particular firearm.
Specialty load families
Reduced-recoil, subsonic, monolithic, and heavier-bullet offerings are product-specific. A +P marking is a pressure category where standardized, not simply a heavier bullet. Follow the maker’s exact product and firearm guidance.
The expanded factory selection spans 230 grains. Exact products and source conditions appear in the table.
Bullet construction background: Hornady: anatomy of a bullet ↗. Exact product descriptions and velocities are cited in the factory table.
The table also distinguishes ordinary factory loads. Published test conditions and product-specific notes accompany each addition; no velocity curve is inferred from one muzzle specification.
From the factory catalog
230 grains
880 fps
Full metal jacket
Compare all 2 cited factory load records
| Maker / product | Bullet mass | Published construction | Muzzle velocity | Test barrel | Source |
|---|---|---|---|---|---|
| RemingtonL45GAP4 / 23691 | 230 gr 14.90 g | Full metal jacket | 880 fps 268 m/s | 5 in | Remington · PDF p. 40 ↗ |
| Magtech45GA | 230 gr 14.90 g | Standard · FMJ | 837 fps 255.1 m/s | 5 in | Magtech · PDF p. 6 ↗ |
Explore the published data
Ballistics you can inspect
Select a legend entry to add or remove its line. Hover or tap a plotted point, or use the position slider. With the graph focused, arrow keys move the inspector. Solid dots identify source points; dashed connectors show estimates between them. Load construction, pressure category, and test setup can differ even at the same grain weight.
Read the original values as accessible tables
.45 GAP: factory velocity downrange
| Exact load | Source / publisher | Published points |
|---|---|---|
| 230 gr Remington Full metal jacket | Remington | 0: 880; 25: 860; 50: 841 |
| 230 gr Magtech Standard · FMJ | Magtech | 0: 837 |
How to interpret the comparison
Changing bullet weight also often changes bullet design and propellant choice. Two curves are comparisons of the listed products, not a controlled experiment proving that bullet weight alone caused the difference. Catalog downrange points are projections under the maker’s conditions; barrel-study points are recorded observations in the study firearm.
Direct answers
Common questions
What is .45 GAP?
GAP stands for Glock Automatic Pistol. This is a distinct, shorter-case .45-caliber semiautomatic-pistol cartridge, rather than another name for .45 ACP.
What diameter does .45 GAP use?
The cited dimensional standard lists 0.4520 inches (11.481 mm), bullet maximum. This drawing convention is different from a casual caliber nickname.
Are similarly named cartridges interchangeable?
.45 GAP and .45 ACP are separate chamberings despite similar bullet diameters.
Are the graph values measured or estimated?
Factory datasets show manufacturer specifications and any published downrange projections. Chronograph and barrel-study datasets identify recorded measurements and the original test source. Dashed connectors and intermediate inspector values are labeled linear estimates; single source points are not extended into invented curves. Energy is calculated from bullet mass and velocity.
Does higher energy mean the best load?
Energy is calculated from mass and velocity. It does not establish accuracy, expansion, penetration, pattern density, recoil, or suitability for a particular firearm. Use the exact product documentation and firearm manual.
Trace the facts
Sources & methodology
Skives & petals: read the jacket construction →
Compiled by 2A Ledger from the linked standards, manufacturer publications, and identified test records. Checked October 18, 2026. Historical tests and older catalogs retain their original dates; a listing here does not establish current availability.
- SAAMI: dimensional drawing · PDF p. 60 ↗
- Remington · PDF p. 40 ↗
- American Rifleman: GLOCK development history and 2003 GAP introduction ↗
- GLOCK: official cartridge-family description ↗
- Additional factory specification / original test ↗
Diameter figures preserve the cited drawing convention. Inch–millimeter conversion uses exactly 25.4 mm per inch. Factory specifications describe the maker’s test setup; your firearm, ammunition lot, temperature, and measuring method can produce different results. This is an educational factory-ammunition reference, not a reloading manual.