Searched both forums here and Steam. Posted on Steam, but I don't think that somebody read it. Plus, as wiki says nobody cared about this feat since 0.1.14.0.
1. Incendiary Pistols issue #1
The current math: original_bonus_dmg * (2+ (0.07 * spec_points))
Should be at least (at best totally reworked, see below why): original_bonus_dmg * 2 (Mad Chemist itself) * (1 + 0.07 * spec_points)
2. Incendiary Pistols issue #2
Mad Chemist by some reason affects number of turns of On-Hit effects. This works badly in current implementation.
Q149 example, the current math:
Original dmg bonus 227% over 6 turns (?). I can't check but I feel that Mad Chemist multiply by 2 and number of turns too. The last thing is bad, see below why.
Mad Chemist, SpecPoints (SP for brief) 0: 454% dmg over 6 turns, dmg per turn 75.6% (454/6)
Mad Chemist, SP 1: 469% dmg over 6 turns, 78.16% per turn
Mad Chemist, SP 2: 485% dmg over 7 turns, 69.28 per turn <-- who needs less dmg per turn?
2. Cryoliquid Pistols issue
The issue is that they don't get any bonuses of spec points in Mad Chemist feat.
Can't check, but I think they get additional frozen turn with SP 8-10. For instance, with SP 0, you may freeze a target for 2 turns. With SP 8: for 3 turns. Math probably is number_of_turns * (1+0.07 * spec_points).
IMHO, such "bonus" of "wasted" 8 spec points is pointless for any build on any difficulty.
Additionally, I may say that any cryo pistol should have the effect to shatter frozen targets _by_design_, like Cryogenic Induction feat, but without this feat. Otherwise, the usage of cryo pistols is very low, so you may throw them in a trash can. Even their shots do break frozen state.
Additionally, neither cryo pistols nor fire pistols have better ammo, nor feats. For Q149 fire pistol example above, the "additional damage" is 50 dmg per turn. Exactly such value you may get, the math is like this:
1. Additional dmg is taken from a separate roll. It includes your effective dmg of a weapon. Q149 produces 25-42 fire pistol. With guns 130 the effective dmg for this pistol is about 60-90.
2. 60-90 * 75% = 45-67. This is the range of regular "additional" damage per turn.
3. With SP 2 in Mad Chemist the range is 60-90 * 69.28% = 42-63 per turn.
Needless to say, that if first shot was a critical hit, the bonus dmg will also be critical. But next regular hit may override this bonus dmg, because the additional dmg is taken from a separate roll. In the end, all this looks very very sad.
But there is good news too, at least acid pistols deal +/- decent damage.
In the end, fire pistols and cryo pistols in the current state look useless:
* low base dmg
* high AP cost
* "overrides" previous bonus dmg
* fire effect lasts lots of turns, but panic lasts 2 turns, then aphobia 3 turns
* no shattering out of box
* low range and low precion lead to lots of misses, in the end lots of quick loads
* dmg don't scale with anything except Guns skill
* crit chance is low
* wearing any of 2 exclusive chem belts costs you an extra slot (for toxic grenades, but you can't take them now)
* cryostasis of cryo pistols don't deal any additional dmg, in conjunction with low base dmg ... Crowbar is even better than this (I'm joking, but any joke has part of truth).
* cryo pistols don't receive any significant bonus of Mad Chemist's spec points
* dmg/turn of fire pistols become worse if you spend spec points to Med Chemist
Looks like I am the only one who whining about this after 7 years since the game was released. There is no hope that anything would be fixed (new project, Underrail development is frozen, etc, etc), but somebody should tell this at one day.
Thank you for reading. Have a nice day.