A reliable Risk of Rain 2 Railgunner build supports accurate weak-point shots, a repeatable reload rhythm, and enough movement to create another firing angle. Use M99 Sniper as the burst foundation, prioritize useful damage items such as Crowbar and the Bands, and value attack speed for its reload and special-skill benefits. Add movement before the inventory becomes a strong rifle attached to a survivor who cannot escape.
Railgunner converts critical-strike chance into critical-strike damage through Magnetic Accelerator. She does not roll ordinary random critical hits: scoped weak-point hits provide the critical strike. Lens-Maker's Glasses therefore supports the damage multiplier of a successful weak-point attack, but it does not rescue a missed weak point or turn every unscoped tracking round into a random critical hit.
Build around the shot-and-reload sequence first
M99 Sniper changes the primary into a heavy piercing railgun shot while scoped. After the shot, unscoping introduces Active Reload. Timing the reload correctly lets you recover faster and adds 500% base damage to the next relevant scoped or special shot. That bonus is a specific amount of base damage, not a promise to multiply the entire next hit by five.
Begin with the sequence you can repeat under pressure: identify the weak point, fire, unscoped reload, then find the next target. The damage items become more valuable when that sequence remains consistent. Failing the reload repeatedly introduces downtime that an extra offensive pickup may not compensate for.
Do not remain scoped after every shot simply because your next target is still visible. Check the space around Railgunner, complete the reload, and decide whether the original firing position is still usable. A good shot followed by a stationary death does not make a successful damage cycle.
The perfect-reload bonus can be consumed by a subsequent M99 shot even when that shot misses. Treat the next shot as a deliberate attack. If you are firing hastily into terrain, you are losing both the opportunity to damage the target and the stored bonus you just earned.
Understand critical damage without confusing it with critical chance
Magnetic Accelerator adds converted critical chance to the base critical-strike damage multiplier. For example, 50% critical chance changes a 200% multiplier to 250%. That is a 25% increase relative to the original 200% critical hit, rather than 50% more total damage. This distinction matters when comparing an item choice with another damage source.
Lens-Maker's Glasses remains useful, but judge it from that conversion. A weak-point hit already guarantees the critical strike. The item increases how hard that hit lands rather than changing the probability of a critical roll. Laser Scope provides another critical-damage route and fits the same emphasis on accurate weak-point attacks.
A larger number on the critical-damage multiplier is not universal extra damage to everything Railgunner does. Unscoped XQR shots do not hit highlighted weak points, so the passive's benefit is tied to the attacks that use that system. Build your inventory with the balance of scoped and unscoped actions you actually perform.
When a target's weak point is difficult to track, choose a safer angle or use the appropriate fallback attack. Do not insist on firing a high-value shot through an unreliable line simply because the inventory is heavily invested in critical damage. A successful shot from a new position is the practical way to use the investment.
Use Crowbar and Bands for meaningful burst
Crowbar rewards attacking a target while it is above its health threshold. Railgunner can exploit that condition with a large opening shot on a fresh enemy. Decide which target deserves the opening hit and avoid accidentally wearing it below the condition with small attacks before the main shot arrives.
Crowbar does not stay active throughout a boss fight merely because your first shot used it. After the boss is damaged, continue with the rest of the build's strengths: weak points, reload bonuses, Bands when ready, and useful item effects. Assess repeated damage separately from the first-hit window.
Kjaro's Band and Runald's Band trigger from qualifying high-damage hits and then recharge. M99's heavy shot provides a natural trigger when they are available. One gives a flame effect, while the other provides an ice blast and slow. Both can add value to the same qualifying attack.
Do not count on a Band effect after every rapid shot. The recharge condition still applies. Likewise, Luck is not what makes the Bands' deterministic threshold trigger available. If you take a Luck item, evaluate its interactions with the actual chance-based effects in the rest of the build.
For HH44, consider the shot's damage and any critical or other applicable amplification when assessing the Band threshold. Its ordinary 400% shot is not automatically more than the more-than-400% trigger condition. M99's larger hit is the more straightforward foundation when the inventory is specifically organized around that trigger.
Give attack speed a practical role
Soldier's Syringe helps Railgunner in more ways than making the unscoped primary fire faster. Increased attack speed widens the perfect-reload zone, making the timing easier, and reduces the preparation and weapon-disable duration associated with Supercharge. These benefits can improve how reliably you execute the build.
A few useful attack-speed pickups may therefore be worth taking even when the central attack is a single large shot. Compare the entire firing cycle rather than only the damage printed on M99. A smoother reload or shorter vulnerable period after a special can create more usable attacks across a fight.
Predatory Instincts can interact with weak-point critical strikes to support attack speed. It belongs to a plan where you continue landing those attacks, rather than a theoretical buff you expect to maintain while missing or firing only unscoped rounds.
Attack speed does not replace cooldown reduction for every skill. Do not assume an item's effect on the reload or Supercharge means it also reduces the Concussion Device's ordinary recharge. Evaluate each mechanic separately and read the relevant skill behavior rather than applying one speed label to the whole kit.
Keep Concussion Device available for the next safe angle
Concussion Device pushes Railgunner and nearby enemies. It has two charges and can provide both separation and movement. Use it proactively when enemies begin closing the space needed for scoped aiming, rather than waiting until every exit is already blocked.
Its push depends on current movement and direction relative to the device. Jumping just before the detonation can provide a stronger upward launch. Practice the timing where an unsuccessful attempt is survivable before using it as the only escape from an important encounter.
The explosion itself deals no damage. It is a positioning tool, not another on-hit damage source for your inventory. It also does not automatically grant fall-damage immunity during the launch, so a very high trajectory can create a dangerous landing. Track the route down as well as the initial height.
Polar Field Device offers an alternative slowing field for enemies and projectiles. It can make a firing opportunity easier to manage, but it trades the default movement option for a different kind of control. Choose it when that control fits your route and you already have a plan for escaping close threats.
Commit to Supercharge with a recovery plan
Supercharge produces a large piercing shot with an additional weak-point benefit. It is a strong tool for a target you can aim at safely during the preparation and release. It also disables the relevant weapons after firing, so the damage window has an explicit recovery cost.
Before activating it, identify the target and the path you will take afterward. Reserve a useful utility charge when possible. Your utility is not disabled by the shot's weapon lockout, which gives you a way to reposition while the main attacks recover.
The prepared shot is available only for a limited firing window. You cannot hold it indefinitely while waiting for the target to become convenient. If a safe shot disappears, account for the lost opportunity and cooldown rather than firing blindly just because you started charging.
Increased attack speed reduces both the preparation and weapon-disable duration. This makes attack-speed support particularly useful when the aftermath of Supercharge is causing deaths. A high opening damage number is only part of the build; surviving long enough to return to normal M99 shots completes the cycle.
Cryocharge is a lower-damage alternative with freezing and no corresponding weapon-disable period. It can be useful when the default special's recovery cost repeatedly breaks your flow. Freezing is not universal to every boss, and enemies brought into the execute range need a follow-up damage instance for the execution. Do not plan around freezing any enemy simply because the skill has that keyword.
Decide whether M99 or HH44 suits your hands
HH44 Marksman uses a shorter-range scope and fires without the M99 Active Reload sequence. It supports a different rhythm: repeated scoped shots instead of a single heavy shot followed by a timed reload. The absence of that timing requirement can make practical damage more consistent for a player who struggles to reload during busy encounters.
The trade also changes item evaluation. HH44 does not benefit from the perfect-reload bonus or Backup Magazine in the same way as M99. Attack speed can directly support its firing rhythm, while the larger default M99 hit makes burst-triggered plans more straightforward.
Backup Magazine lets M99 fire additional consecutive shots before reloading. Only the first shot after a perfect reload gets the stored bonus, and the charges reload together. It can provide another shot when you need it, but it is not a reason to stop learning the reload mechanic or assume every shot in the magazine carries the bonus.
Choose the secondary from the loop you can execute while moving and tracking enemies. A theoretically stronger attack that produces frequent missed weak points and failed reloads may be less useful than the alternative you can land repeatedly. You can change the loadout between runs and compare specific problems rather than treating the initial choice as permanent.
Assess inventory gaps instead of waiting for a complete item list
If you kill single targets quickly but small enemies keep closing in, invest in practical area damage and use the XQR fallback when scoped shots are awkward. If shots land but recovery is unsafe, prioritize movement and attack-speed support. If damage remains low, inspect weak-point accuracy and reload use before blaming the loot.
A normal run will not always offer Crowbar, both Bands, critical-damage support, and the ideal defensive items together. Take improvements that address the current gap. Keep a reliable firing angle, preserve a utility route, and use each large attack on a target that matters. That makes the Railgunner build function across ordinary loot variation instead of depending on one perfect inventory.