лучше смотреть надо
fiRing plasma weapons
Plasma weapons can be used in two firing modes: standard mode (the normal and safest method), or a higher-powered blast with a longer range and higher temperature. The latter requires a short time to replenish the plasma back to firing levels. When an Astartes plasma weapon fires in Maximal mode, it gains an extra 10 metres to range, 1d10 to Damage, and +2 Pen, but uses 3 rounds of ammunition. The Maximal setting also adds the Recharge and Overheats Qualities to the weapon, but increases any Blast Quality by +2 (so an Astartes Plasma Cannon would fire a Blast (3) on Maximal).
стр. 147 WH 40k Deathwatch - Core Rulebook
Firing Plasma Weapons
Plasma weapons can be used in two firing modes—single
shot (the normal and safest method), or a higher powered
blast with a longer range and higher temperature. The
latter though requires a short recharge time to replenish the
plasma and bring it to firing levels; this time will vary with
the level of precision technology used in construction. Like
most Imperial devices the older it is the better it is; the more
ancient Craftsmanship almost always indicates the superior
design. Imperial plasma weapons can fire in Maximal mode,
gaining an extra 10 metres to range, 1d10 to Damage and
+2 Pen, but use 3 rounds of ammunition. When fired on the
Maximal setting, plasma weapons gain the Recharge Quality.
Additionally, plasma weapons with the Blast Quality firing
in Maximal add +2 to the Blast (so a Ryza-pattern plasma
cannon would fire a Blast (3) on Maximal setting).
стр. 123 WH 40K Rogue Trader - Core Rulebook
и в ДХ тоже наверняка есть это правило, лень уже искать.