Best Weapon Upgrades in GTA Online 2025: Mk II Weapons Guide
· Category: guide
Weapon Upgrades: Maximizing Your Combat Potential
GTA Online's Mk II weapon system transforms basic firearms into specialized tools of destruction. This guide covers every upgrade worth your money.
Understanding Mk II Weapons
What Are Mk II Weapons? Upgraded versions of base weapons with:
- Increased damage
- Custom ammunition types
- Visual modifications
- Improved statistics
Requirements:
- Bunker with Weapon Workshop OR
- MOC with Weapon Workshop OR
- Avenger with Weapon Workshop OR
- Terrorbyte with Weapon Workshop OR
- Agency with Armory
Mk II Upgrade Costs
Research Requirement: Most Mk II components require Bunker research (random unlock order)
Base Conversion Costs:
| Weapon | Conversion Cost |
|---|---|
| Pistol Mk II | $73,750 |
| SMG Mk II | $85,500 |
| Assault Rifle Mk II | $98,750 |
| Carbine Rifle Mk II | $107,500 |
| Combat MG Mk II | $119,000 |
| Heavy Sniper Mk II | $165,375 |
| Marksman Rifle Mk II | $149,000 |
| Pump Shotgun Mk II | $82,500 |
Top 5 Essential Mk II Upgrades
1. Heavy Sniper Mk II
Why It's Essential: The most important weapon upgrade in the game. Explosive rounds one-shot most vehicles.
Key Stats:
- Explosive rounds available
- Extended range
- Thermal scope option
Ammunition Types:
| Ammo | Effect | Best For |
|---|---|---|
| Standard | Normal damage | General use |
| Armor Piercing | +20% damage to armor | PvP |
| Incendiary | Fire damage over time | NPCs |
| Explosive | Vehicle damage | Anti-vehicle |
| Full Metal Jacket | Penetration | Cover enemies |
Best Setup:
- Explosive rounds (anti-vehicle)
- Extended clip
- Heavy barrel
- Thermal scope (optional)
2. Combat MG Mk II
Why It's Essential: The best all-around automatic weapon for PvE and PvP.
Key Stats:
- Highest DPS automatic
- Large magazine
- Controllable recoil
Best Setup:
- Extended clip (200 rounds!)
- Heavy barrel
- Holographic sight
- Standard ammo
3. Carbine Rifle Mk II
Why It's Essential: Reliable, accurate, and effective at all ranges.
Best Setup:
- Extended clip
- Heavy barrel
- Holographic sight
- Armor piercing rounds (PvP)
4. Pump Shotgun Mk II
Why It's Essential: Explosive slugs make it a pocket rocket launcher.
Ammunition Types:
| Ammo | Effect |
|---|---|
| Standard | Normal shotgun spread |
| Flechette | Armor piercing |
| Incendiary | Fire damage |
| Explosive | Mini explosions |
| Steel Buckshot | Increased damage |
Best Setup:
- Explosive slugs
- Extended clip
- Holographic sight
5. Marksman Rifle Mk II
Why It's Essential: Best mid-range weapon for PvP combat.
Best Setup:
- Extended clip
- Heavy barrel
- Large scope
- Armor piercing rounds
Special Ammunition Guide
Explosive Rounds (Heavy Sniper):
- 40 round capacity (expandable to 48)
- $950 per 4 rounds
- One-shots helicopters
- Damages Oppressors
- Essential for anti-griefing
Incendiary Rounds:
- Sets targets on fire
- Damage over time
- Effective against NPCs
- Less useful in PvP
Armor Piercing:
- Ignores body armor
- Essential for PvP
- Available for most rifles
Hollow Point:
- Increased damage vs unarmored
- Decreased damage vs armored
- Situational use
Thermal Scope
Available For:
- Heavy Sniper Mk II
- Assault Rifle Mk II
Benefits:
- See through smoke
- Spot hidden players
- Night vision capability
- Essential for thermal vs thermal fights
Limitation: Cannot use with explosive rounds simultaneously on some platforms
Weapon Workshop Locations
| Location | Cost | Notes |
|---|---|---|
| Bunker | +$245,000 | Original location |
| MOC | +$245,000 | Mobile option |
| Avenger | +$245,000 | Flying workshop |
| Terrorbyte | +$495,000 | Best for Oppressor too |
| Kosatka | +$240,000 | Submarine option |
| Agency | +$380,000 | Convenient location |
Research Priority
High Priority Research:
- Explosive rounds (Heavy Sniper)
- Mk II weapon mods
- Oppressor missiles
- Thermal scope
Fast-Track Cost: $225,000 per research item
PvP Loadout Recommendation
| Slot | Weapon | Setup |
|---|---|---|
| Primary | Combat MG Mk II | Extended, heavy barrel |
| Sniper | Heavy Sniper Mk II | Explosive rounds |
| Shotgun | Pump Shotgun Mk II | Explosive slugs |
| Rifle | Carbine Rifle Mk II | AP rounds |
| Special | Up-n-Atomizer | Utility |
PvE Loadout Recommendation
| Slot | Weapon | Setup |
|---|---|---|
| Primary | Combat MG Mk II | Extended clip |
| Sniper | Heavy Sniper Mk II | Standard rounds |
| SMG | SMG Mk II | Extended, suppressed |
| Shotgun | Assault Shotgun | Standard |
Conclusion
The Heavy Sniper Mk II with Explosive Rounds is the single most important weapon upgrade in GTA Online. Follow that with the Combat MG Mk II for general use. These two weapons handle 90% of combat situations effectively.