In Battlefield 4, grenade launchers play a significant role in diversifying combat strategies, offering a range of underbarrel attachments and standalone systems. Below, we delve into the various grenade launchers and their functionalities:

1. Underbarrel Grenade Launchers
– Functionality: These attachments enhance primary weapons, allowing players to seamlessly switch from conventional bullets to grenades.
– Examples:
– M320: This launcher is versatile, serving both as a standalone weapon and as an underbarrel attachment.
– SFAR-M GL: Another notable platform, this launcher provides effective grenade-launching capabilities directly from an assault rifle frame.
– Caliber and Types: Underbarrel launchers typically fire 40mm rounds, available in several types that suit different combat scenarios.

2. Types of Grenade Rounds
– 40mm HE (High-Explosive): Ideal for anti-infantry engagements, delivering fragmentation effects to damage clusters of enemies.
– 40mm Smoke: Utilized for creating visual cover, beneficial for team movements or to obscure enemy sightlines.
– 40mm Incendiary: Inflicts damage over time due to fire effects, useful for flushing out enemies or denying areas.
– 40mm AP (Armor Piercing): Designed to penetrate armor, effective against vehicles, though its availability is dependent on the game mode.

3. Special Grenade Launchers
– M320 3GL: Distinguished as a tri-barreled grenade launcher with semi-automatic firing. It holds three shots internally and allows players to unleash two volleys before needing to reload, making it a potent choice in intense firefights.
– Damage Output: Each grenade inflicts approximately 77 damage per direct hit.
– Unlock Requirements: To gain access, players must secure kills using the M320 Dart and LVG grenades.

– Limited Velocity Grenade (LVG): Recognized as a projectile that withstands high speed, necessary for unlocking advanced grenade launcher variants.

– M320 Dart: Functions similarly to a shotgun round, allowing one powerful shot before the necessity to reload.

4. Underbarrel Attachment Mechanics
– Toggle Functionality: Players can easily switch between firing standard bullets and grenade rounds, enhancing tactical options in various combat scenarios.
– Ammunition Resupply: One challenge noted with underbarrel launchers is inconsistent ammunition resupply. Often, players may need to switch weapons or respawn to fully restock their grenade supply due to resupply bugs present in some game versions.
– Limited Capacity: Typically, underbarrel launchers allow for 3 grenades per reload, emphasizing the need for careful ammo management during engagements.

5. Usage Tips and Tactical Considerations
– RGO Impact Grenade: With an instant detonation feature upon surface impact, this grenade is suitable for quick attacks but has a smaller damage radius (~64 damage), making it ideal for strategic placements or air-lobbing.
– Ammo Management: Given the potential resupply issues, players need to be strategic about their usage and remain vigilant about securing additional grenade resources during matches.

Conclusion
In Battlefield 4, grenade launchers, particularly through underbarrel attachments like the M320 and M320 3GL, offer versatile weaponry suited for a variety of combat situations. With multiple grenade types available that cater to different battlefield roles, players can implement effective strategies for engaging enemies, utilizing smoke for cover, incendiary rounds for area denial, or armor-piercing rounds for vehicle engagements. However, mindful management of ammunition, along with an understanding of the mechanics at play, is essential for maximizing the potential of these formidable weapons.