Here me out, firearm ace is so good that all builds my players have done includes it. Probably because the other level 1 feats feels underwhelming but it does make the game in lower levels just be "strike, reload, strike. It is also less needed as there will be martial weapon choices in comparison to crossbows. If anything, this feat belongs to the ranger or be meshed in with crossbow ace into a reload ace.
What I am trying to say is that 'fireatm ace' is too good for its own good even if the class will not use it too often due to quick draw or similar.
One pistolero build went like this @ level 4
Firearm ace
Quick draw
Running reload
Turn 1, draw 2 pistols, shoot both, drop, quick draw a MUSKET, turn 2 reload shoot reload and cue in the rotation. Mostly because of firearm ace. Considered dropping the pistols higher levels just because of runes, retraining quick draw to risky reload.
If we must have a "flat damage boost" put in point blank shot or something else but I'd rather have this circumstance bonus be a part of the guns themselves or a class feature somehow. I want the level 1 choice be a choice.
On a ranger, firearm ace would be a choice compared to its other feats.
I have done 3 short scenarions and 1 slightly longer as a GM