Best Weapon Upgrades - The Callisto Protocol Guide - IGN (2024)

You can choose from dozens of weapon upgrades in The Callisto Protocol to help Jacob escape Black Iron Prison—but some are more useful than others. This page contains a ranking of the best weapon upgrades in the game, including their costs, usefulness against enemy types, and when you can access them in the story.

For more info on each weapon in The Callisto Protocol, check out our Weapons page here.

Best Weapon Upgrades in The Callisto Protocol

You'll get the chance to upgrade your weapon for the very first time in Chapter 2: Outbreak, when Elias hands you a dead guard's pistol for you to print in the Reforge.

Upgrades can be purchased in the Reforge using Callisto Credits, and you can find these credits throughout the game from numerous sources:

• Dropped by dead enemies
• Scattered randomly
• Inside Loot Crates, boxes, and lockers
• By selling contrabands in the Reforge

Click the links below to jump into a specific section:

• S-Tier Upgrades
• A-Tier Upgrades
• B-Tier Upgrades
• C-Tier Upgrades

S-Tier Upgrades

S-Tier signifies the weapon upgrades you should prioritize before others.

BI-55 Pistol "Hand Cannon"

Though it is your first range weapon, the Hand Cannon is arguably your most important weapon in the game. It's accurate enough to tear certain limbs and sufficient to two-shot most enemies once you unlock the Magnum Rounds.

Upgrading this weapon to the max will benefit you in the long run, especially after purchasing the TK23 "Boom Bullets," which adds an alternative fire that shoots explosive rounds.

• The explosive shells will one-shot most common enemies and deal severe damage to more powerful mob types, even the tentacle mutates.

GRP (Gravity Restraint Projector)

The GRP is your best friend and will carry you for most of the game. Against multiple enemies, the GRP can be used to kill enemies instantly by pulling then pushing them into environmental hazards.

After upgrading the energy capacity, purchase the first-tier upgrades for the recharge speed and the launch strength. These two will ensure that you can throw multiple enemies to a wall spike or other traps without being right next to them.

A-Tier Upgrades

A-Tier Upgrades are great weapon unlocks, but you won't need to upgrade them fully.

Stun Baton

Though crucial, your primary melee weapon only requires some upgrades for you to maximize its utility. Its first upgrade, the Heavy Attack, combined with the perfect dodge, should be your bread and butter against multiple enemies early in the game.

Your priority for the Stun Baton is to unlock the Increased Velocity Alloy Sheath and its increased damage upgrades. The former is needed to hit enemies without being extremely close-quarter.

Maximizing the blocking upgrades can be helpful but are nonessential since you will be dodging enemy attacks most of the time. However, purchasing the Blocking Protection will completely negate any melee damage if you must.

TK4 Riot Shotgun "Riot Gun"

The only reason the Riot Gun is not in S-Tier is how late you get this weapon in the game.

You can opt-out of the Explosive Rounds upgrade for the Riot Gun, as the gun's base damage is already noteworthy. However, you can purchase the Magnum Rounds upgrade to boost the damage a little bit more.

• Besides that, this gun, alongside the pistol, should be your two-weapon combo for the rest of the game.

Check out our guide on how to beat the Two-Head with these two weapons here.

B-Tier Upgrades

B-Tier Upgrades are optional weapons. There are far better alternatives that prove far more beneficial than these.

Skunkworks Shotgun "Skunk Gun"

This prototype shotgun can be found in Chapter 3: Aftermath, shortly after the elevator crashes down to the basem*nt. You'll need to bring the schematics to the Reforge and unlock it for 800 Callisto Credits.

The Skunk Gun is a lesser combination of the Hand Cannon and the Riot Gun. The latter is a far better alternative, with cheaper upgrade costs, and you can use it for free.

UJC Special Ops "Tactical Pistol"

You can find the schematics for the Tactical Pistol in Chapter 6: Below, right after encountering the blind mutates for the first time.

• Though equipped with low recoil and a high rate of fire, the Tactical Pistol is too weak to be helpful.

Upgrading this weapon to the max allows you to have the game's lowest recoil and highest ammo capacity weapon. Still, its damage upgrade is so woeful that spending 3,600 Callisto Credits for its final upgrade feels like a robbery.

C-Tier Upgrades

The last tier in this list, C-Tier Upgrades, are upgrades that are simply a waste of your cash. Spending your Callisto Credits to strengthen your other weapons than those below is highly recommended.

UJC Special Ops "Assault Rifle"

The Assault Rifle is the only fully automatic gun in the game, and you can find the schematics for the weapon at the start of Chapter 7: Colony.

While the Assault Rifle is excellent at taking down multiple enemies with one magazine, the expensive ammo and its cost to unlock (1,000 Callisto Credits) make this gun unrewarding for the remainder of the story. Rather than spending thousands of credits to make this gun somewhat valid, you can use it to upgrade your other weapons to their max potential.