Most of below is just clarification of the rules in the Core Rulebook (i.e. how does a 30-degree cone of flame work?). Actual modifications to Core Rulebook include: Mighty Shot Talent not applicable with Flame Weapons & weapon malfunction rules.

WIDTH OF FLAME CONE
Calculate the width of the cone as a function of the distance from the shooter. Its a linear function and ends at the weapons given Range. The width at any point is ~0.54 * the distance from the shooter, which is 5.4m at 10m range, 10.8m at 20m and so on per table below:

Distance From Weapon (meters)	Width of Cone of Flame (meters)
1	0.54
5	2.68
10	5.36
15	8.04
20	10.72
25	13.40

TO HIT

• No Ballistic Skill Test is made.
• Cover may not provide protection – horizontal cover provides no protection.
• If target is aware of attack – target makes Agility Test or Dodge Test (target’s choice) to dive out of way of the cone of flame (up to their Agility Bonus).
  • Dodging area attack rules apply – DH pg 193.
  • Note that Dodge Test would use up their Reaction while Agility Test would not.

Modifiers to this roll are:

• +30 if attacker is using unbraced Heavy Flamer
• +20 if attacker does not have Skill in the flame weapon
• +20 if attacker is using a pistol in his off-hand
• +20 if attacker is firing a Basic weapon (long arm) with one hand
  If Agility/Dodge successful, that character has physically moved out of the area of the flame cone.
  Mighty Shot Talent modifier to damage does not apply to Flamer Weapons as you’re not actually “targeting” anything.
  If at least 1 point of damage is taken by target then target makes Agility Test (not Dodge Test) to avoid catching on fire.

FLAMER MALFUNCTION
Only the first damage roll made from a single flamer shot determines if there is a weapon malfunction (e.g. if there’s multiple targets hit from a single flamer shot, the damage roll to the 2nd target cannot cause a malfunction).

If damage roll comes up a 9 then there is no damage as the Flamer malfunctioned – roll 1d10:
1-2: Ignitor flame went out on weapon; target was sprayed with non-burning promethium. Remaining fuel (ammo) still good but roll BS each subsequent turn to re-light ignitor flame.
3-8: Clogged nozzle causes pressure to build blowing safety valve on fuel tank which dumps all remaining fuel on ground, preventing possible catastrophic result. Roll BS Test to unclog nozzle & then need to reload tank with fuel.
9-10: Flame spreads to fuel tank, which erupts in flames. Roll Agility Test (not Dodge Test) to quickly toss weapon/tank away or suffer weapon’s attack damage (to Body). If at least 1 point of damage is taken from attack then roll another AG Test to not catch on fire.