# Mobile Mortars (DD-021)

> A mortar is a light, smoothbore tube that a small crew can carry and set up on a bipod and baseplate. A round dropped down the muzzle hits a fixed firing pin at the bottom, which sets off its propellant charge and throws it out at a steep angle (generally above 45 degrees). That high arc lets mortars hit targets behind hills or cover that the crew can't see.

- Department: Military (also History)
- First published: 2026-08-23
- Last updated: 2026-08-23
- Permalink: https://detailenjoyer.com/case/mobile-mortars/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-021-F01**: A mortar fires when a round dropped down the muzzle hits a fixed firing pin at the base, which ignites the propellant charge in its tail. _(Write-up · Exhibit C (Drop it and it fires))_
- **DD-021-F02**: Conventional mortars fire only at high angles (above 45°), so they can hit targets behind hills or cover. _(Write-up · Exhibit E (High-angle fire))_
- **DD-021-F03**: The US M224 60 mm mortar weighs only 18 lb in hand-held mode. _(Write-up · Exhibit G (One soldier can carry a 60 mm))_

## Write-up

Soldiers fire this weapon by dropping a shell down the tube. The round arcs over cover onto targets the crew can't see.

1. **Light, smoothbore and muzzle-loaded**: Mortars are usually smoothbore (unrifled), muzzle-loaded indirect-fire weapons. They are relatively portable, and for a given calibre their barrels are shorter and lighter than an artillery gun's.
2. **Tube, bipod, baseplate**: A mortar has three main parts: the barrel ('tube'), the bipod, and the baseplate. The bipod steadies the tube and adjusts elevation and direction. The baseplate pushes the recoil into the ground, so the tube isn't driven into the dirt.
3. **Drop it and it fires**: In drop-fire mode, a crew member drops the round tail-first down the muzzle. At the bottom it hits a fixed firing pin, which sets off the ignition (propelling) cartridge in the tail. The burning propellant's gas then drives the round up and out of the barrel.
4. **Fins, not spin**: All US Army mortar cannons are smoothbore and fire fin-stabilized projectiles. The round's tail fins keep it stable in flight, instead of the spin a rifled barrel would give it.
5. **High-angle fire**: Conventional mortars fire only at high angles (above 45°), so their rounds come down steeply. That makes them ideal for hitting targets in defilade: dug-in troops or anything behind cover that direct-fire weapons can't reach.
6. **Range is set two ways**: Mortar crews adjust range by changing the barrel's angle (higher means shorter) and by adding or removing propellant increments on the round.
7. **One soldier can carry a 60 mm**: The US M224 60 mm lightweight mortar weighs 46.5 lb in conventional mode and 18 lb in hand-held mode. It breaks down into barrel, bipod and baseplate, can be carried by one crew member without disassembly, and reaches about 3,490 m.

## Related case files

- [Shoot-and-Scoot (DD-736)](https://detailenjoyer.com/case/shoot-and-scoot/): Another indirect-fire weapon

## Reel vs. record

- **Imprecise**: 'strikes a firing mechanism and ignites its propellant'. In drop-fire, the round's tail hits a fixed firing pin at the base of the tube. That fires the primer in the round's ignition (propelling) cartridge, which then lights the propellant increments. The pin is part of the tube, not a separate mechanism in the round. [Open Source Munitions Portal; CEW Annex C]
- **Added context**: 'steep ballistic trajectory' means high-angle fire, above 45° for conventional mortars. [CEW Annex C]
- **Otherwise accurate**: tube/bipod/baseplate, muzzle loading, fin-stabilized rounds and indirect fire at targets out of line of sight all check out.

## Video: Mobile Mortars: Soldiers Fire This Weapon by Dropping a Shell Down the Tube

- Duration: 21.5 s · Published: 2026-08-23
- File: https://detailenjoyer.com/assets/videos/DcY-I8VxTJ0.mp4

### Transcript

DID YOU KNOW? Portable mortars are lightweight indirect fire weapons designed to be carried and operated by a small crew, typically consisting of a tube, bipod, and baseplate. The crew drops a fin-stabilized mortar round down the muzzle, where it strikes a firing mechanism and ignites its propellant, launching the projectile on a steep ballistic trajectory toward a target that may be out of direct line of sight. NOW YOU KNOW!

## Questions & answers

**Q: What are the three main parts of a typical mortar?**  
A: A mortar is a barrel (tube) on a bipod, seated in a baseplate that pushes the recoil into the ground. _(Source: Write-up · Exhibit B (Tube, bipod, baseplate) · 81 mm, 82 mm & 120 mm Medium and Heavy Mortars (Characterisation of Explosive Weapons, Annex C); Organic Support Weapons: 60-mm Mortar and AT4 (US Navy NRTC 14234, ch. 14, via GlobalSecurity))_

**Q: In drop-fire mode, what actually fires a mortar round?**  
A: The round slides tail-first down the tube and hits a fixed firing pin, which sets off its ignition cartridge. _(Source: Write-up · Exhibit C (Drop it and it fires) · Mortar projectiles (Open Source Munitions Portal); Organic Support Weapons: 60-mm Mortar and AT4 (US Navy NRTC 14234, ch. 14, via GlobalSecurity); 81 mm, 82 mm & 120 mm Medium and Heavy Mortars (Characterisation of Explosive Weapons, Annex C))_

**Q: What keeps a mortar round stable in flight?**  
A: Mortar barrels are smoothbore, so rounds are fin-stabilized instead of spin-stabilized. _(Source: Write-up · Exhibit D (Fins, not spin) · ATP 3-21.90 / MCTP 3-01D, Tactical Employment of Mortars (HQ Dept. of the Army / USMC); Organic Support Weapons: 60-mm Mortar and AT4 (US Navy NRTC 14234, ch. 14, via GlobalSecurity))_

**Q: At what kind of angle do conventional mortars fire?**  
A: Conventional mortars fire only at high angles (above 45°), so the round comes down steeply on targets behind cover. _(Source: Write-up · Exhibit E (High-angle fire) · 81 mm, 82 mm & 120 mm Medium and Heavy Mortars (Characterisation of Explosive Weapons, Annex C); ATP 3-21.90 / MCTP 3-01D, Tactical Employment of Mortars (HQ Dept. of the Army / USMC))_

**Q: About how much does the US M224 60 mm mortar weigh in hand-held mode?**  
A: The M224 weighs 18 lb hand-held and 46.5 lb in conventional mode with bipod and full baseplate. _(Source: Write-up · Exhibit G (One soldier can carry a 60 mm) · Organic Support Weapons: 60-mm Mortar and AT4 (US Navy NRTC 14234, ch. 14, via GlobalSecurity))_

## Sources

- [Mortar projectiles (Open Source Munitions Portal)](https://osmp.ngo/resources/mortars/)
- [Organic Support Weapons: 60-mm Mortar and AT4 (US Navy NRTC 14234, ch. 14, via GlobalSecurity)](https://www.globalsecurity.org/military/library/policy/navy/nrtc/14234_ch14.pdf)
- [81 mm, 82 mm & 120 mm Medium and Heavy Mortars (Characterisation of Explosive Weapons, Annex C)](https://characterisationexplosiveweapons.org/studies/annex-c-81-82-120-mm-mortars/)
- [ATP 3-21.90 / MCTP 3-01D, Tactical Employment of Mortars (HQ Dept. of the Army / USMC)](https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN19389-ATP_3-21.90-000-WEB-1.pdf)

## Cite this case file

Easterling, Marcus. "Mobile Mortars." The Detail Department (DetailEnjoyer), case file DD-021, last updated Aug 23, 2026. https://detailenjoyer.com/case/mobile-mortars/