Terminology & Glossary — Every Term Explained — Iron Nest Wiki

Launch Version / Updated: August 11, 2026

IRON NEST speaks in 1920s artillery jargon mixed with sim-game vocabulary — and the teleprinters will not explain themselves. This is the operator's dictionary: every term used on this wiki, in the game's reports, and in community discussion, defined in plain language with links to the guide that covers it in depth.

A–Z Glossary

Term	Definition
AP (Armor-Piercing)	Shell type for bunkers, armored targets and underground/hardened positions. Tight 0.14 km blast radius. See shell types.
Ballistic calculator	The machine that converts distance, bearing, shell, powder charges and target classification into a firing card. See ballistic calculator guide.
Barrel heat	Heat accumulated by firing. Safe zone 0–450 °C; past it the loaded shell cooks off — instant game over. See systems & failures.
Bearing	Compass direction to a target, in degrees. A 1° error at 5 km is roughly a 90 m miss.
Blue skull	Map token meaning you hit a friendly unit — the marker of friendly fire.
Bunker buster	The advertised heavy anti-fortification round (among the 30 ammo types); not yet confirmed usable at launch — AP is the current answer to bunkers.
Charge	A powder puck loaded with a shell; more charges = more range. Six levers at the loading platform, one charge each. See loading & aiming.
Class 1–5	Community armor classes for targets, 1 (soft infantry) to 5 (hardest bunkers). See enemy types.
Cook-off	The loaded shell detonating from barrel heat past 450 °C. Mission-ending, unrecoverable.
Counter-battery fire	Enemy artillery firing back at you. Starts a timer the moment your first shell lands on enemy guns. See counter-battery guide.
Counter-battery timer	The countdown started by revealing fire; when it expires, enemy guns strike your position. Destroying batteries and FDCs pauses it.
Emergency move	A purchased relocation of the Iron Nest to escape counter-battery fire; re-verify your map token afterward.
FDC (Fire Direction Center)	Enemy fire-direction brain. Destroying one pauses counter-battery fire — a resource to save, not spend instantly.
Firing card	The calculator's output: gun elevation (lower-left) and rotation (upper-right), attached to your clipboard.
Forward observer	Purchasable spotting asset that adds triangulation data.
HCHE	High-Capacity HE — 0.63 km blast radius, the multi-kill cluster round (5 credits).
HE	High Explosive — the 3-credit workhorse round, 0.27 km radius.
High Command	The teleprinter authority issuing orders; tracks your patience — failures can end in court-martial.
Iris	Map-table tool that visualizes a shell's blast radius before you commit to the round.
Kills per shot (KPS)	Efficiency metric used by gold medals — multi-kills per shell (HCHE is the KPS round).
Minute of Angle (MOA)	Angular correction unit; covers ~0.29 m at 1 km and scales with range. The game's dials use click-steps in MOA terms. See the ballistic calculator guide.
Phosgene	Toxic gas shell that kills personnel and leaves infrastructure intact (1.85 km cloud).
Powder charge	See Charge.
Priority target	Starred objective worth bonus requisition credits — the highest-value target on the board.
Red skull	Map token confirming an enemy kill.
Requisition credits	The game's currency for shells, charges, recon, repairs and upgrades. Do not carry over between sessions. See requisition guide.
S.T.A.R.	Illumination flare (12.74 km reveal). Non-combat; does not trigger counter-battery fire.
Shell selector	Loading-platform lever that brings the chosen shell to the front of the tray.
Skirmish challenges	The two endgame score modes: Challenge (counter-battery pressure) and Chill (volume farming), both with leaderboards.
SMOKE	Screening round (1.86 km radius) for withdrawals and relocations.
Spotter	Front-line observer; reports are direction-only with error that grows with distance — effectively reliable at close range, advisory beyond extreme range (community-reported).
Star shell	Common name for S.T.A.R. illumination.
Tear gas	Non-lethal CS crowd-dispersal round (1.86 km radius); currently little mission use.
Teleprinter	The two ordering machines: High Command (orders) and field reports (intel).
Triangulation	Locating a target from two or more bearing/distance intersections on the map. See target-spotting guide.
Twin guns	The two independent 800 mm barrels — can load and fire separately for double-rate operations.
Weather station module	Chapter 3+ equipment that adds crosswind and barometric pressure to ballistics. See reconnaissance and the ballistic calculator guide.

Acronyms Cheat Sheet

Acronym	Stands For	Meaning in Practice
AP	Armor-Piercing	The bunker/armor round
FDC	Fire Direction Center	Enemy counter-battery brain; killing it pauses the timer
HCHE	High-Capacity HE	The cluster-bomb shell
HE	High Explosive	The workhorse shell
KPS	Kills Per Shot	Gold-medal efficiency metric
MOA	Minute of Angle	The unit of dial corrections
PSI	Pounds per Square Inch	Hydraulic pressure unit — keep in the safe band (see systems guide)
S.T.A.R.	(flavor name — illumination)	The 1-credit flare shell

Cross-Reference by Topic

Topic	Terms	Guide
Shooting	Bearing, charge, firing card, MOA, twin guns	Loading & Aiming
Calculation	Ballistic calculator, firing card, target classification	Ballistic Calculator
Intel	Teleprinter, spotter, star shell, forward observer, triangulation	Reconnaissance
Economy	Requisition credits, priority target, emergency move	Requisition
Survival	Counter-battery fire, counter-battery timer, FDC	Counter-Battery
Machinery	Barrel heat, cook-off, PSI, recoil buffer	Systems & Failures
Targets	Class 1–5, AP, HCHE, bunker buster	Enemy Types

Next steps: Beginner Guide — All Shell Types — Controls & Keybindings