How the to-hit number adds up
Start from your MechWarrior's Gunnery skill, then add the modifiers in GATOR order: Gunnery, Attacker movement, Target movement, Other (heat, damage, woods, cover) and Range. Roll 2D6; if the total equals or beats the number, you hit.
Example: Gunnery 4, you walked (+1), the target moved 5 hexes (+2), medium range (+2). That is a 9, which hits on 10 of the 36 rolls, 27.8%.
Punches and kicks start from Piloting. Heat and sensor damage are not added to them here; use Any other modifier if your table adds them.
What the 2026 Core Rulebook changes here
- Punch −1 (was 0), kick −1 (was −2).
- MRM: no +1 to-hit, −1 on the cluster roll.
- ATM damage groups of 6 (were 5).
- Machine gun array +2 on the cluster roll.
- Acid missiles −1 on the cluster roll (was −2); semi-guided fired without TAG −1.
- Secondary target: the changelog says “a flat +1 per target past the first” and drops the +2 for rear attacks. We read it as +1 on each attack at a secondary target, in any arc (side or rear was +2).
- Hit lower arm actuator: no penalty to that arm's weapons.
- Ultra autocannons no longer jam.
- Aimed shots land on 1D6 4+ (50%), not 2D6 6 to 8 (44.4%).
- The punch table is reversed; each location keeps the same odds.
Not included, because only the paid book has them: the new Large Target modifier and the rewritten partial cover rules for water. Water follows the BattleMech Manual errata in both rule sets.
Questions
What are the odds of rolling 8 or more on 2D6?
15 of the 36 rolls, so 41.7%. A 7+ is 58.3%, 9+ is 27.8%, 10+ is 16.7%, 11+ is 8.3% and 12 is 2.8%. A target number of 2 or less always hits, and 13 or more cannot hit, because a 12 is not an automatic hit.
How do ATMs cluster in the 2026 rules?
You still roll on the column for the launcher size, so an ATM 6 uses the 6 column. The damage now goes in 6-point groups instead of 5, one hit location roll each: the first official Core Rulebook errata, August 2026 (page 2), changes all six ATM entries from C/5 to C/6.
How does the cluster hits table work?
Once the attack hits, roll 2D6 again and read the column for the launcher size to see how many missiles hit. LRM damage is split into 5-point groups, each with its own hit location roll. Each SRM missile and each LB-X pellet gets its own roll. Streak launchers skip the roll: every missile hits. The free rules do not say how to read a modified roll past 2 or 12; we use the 2 or 12 row.
What is the chance of a head hit?
1 in 36 (2.8%) for each hit location roll, from any direction. More groups means more rolls: an LRM 20 that hits makes 2 to 4 location rolls, so its chance of at least one head hit is 8.4%. A punch hits the head one time in six.
Which cluster columns does this cover?
The columns 2, 4, 5, 6, 10, 15 and 20 printed in Catalyst's free quick-start material. That covers SRMs, LRMs, MRM 10 and 20, ATM 6, all LB-X sizes and Ultra autocannons. MRM 30 and 40, ATM 3, 9 and 12 need columns that only the paid rulebooks print.
Is this an official BattleTech tool?
No. It is a free, fan-made helper, not made or endorsed by Catalyst Game Labs or Topps. Every number comes from Catalyst's free downloads, listed under Sources with page numbers. Check your own rulebook for anything this page does not cover.
Sources
Catalyst's free downloads; pages are pages of each PDF.
- A Game of Armored Combat reference card, 7th printing: modifiers, hit location and cluster tables (page 1); punch, kick, physical attacks, attacks between levels and moving into water (page 2).
- Salvage Box Quick-Start Rules: automatic hits and misses (page 7), pulse lasers (page 8), woods and line of sight (pages 5, 8), damage groups, Streak and Ultra (page 10).
- BattleTech Core Rulebook errata thread on the official forum, with the changelog of every 2026 rule change (30 May 2026; pages 1, 2 and 4) and Core Rulebook errata, August 2026: ATM damage groups (page 2).
- Classic BattleTech Miniatures Rules: walking into depth 1 water is a level change (page 7); shots that hit the covered part hit the cover (pages 12, 13); partial cover for weapon and physical attacks (pages 14, 22); MRM, LB-X and damage groups (page 18).
- ilClan era rules insert: LB-X, Streak, Ultra (page 5).
- BattleMech Manual errata, September 2023: partial cover from water and from buildings, punches against prone ’Mechs (page 3); punches and kicks at a ’Mech in water (page 4); targeting computer (page 16).
Fan-made and unofficial. BattleTech and ’Mech are trademarks of The Topps Company, Inc.; this site is not affiliated with Topps or Catalyst Game Labs.