[RPG] Will I ruin Pathfinder if I discount firearms

I'd recommend taking a look at the recent D&D Gamma World game, and how they abstract weapons, including guns.

For ranged weapons, you have three choices to make: one or two handed; light or heavy; "gun" or "weapon"

• one handed weapons do less damage and have less range when compared to two handed weapons.
• light weapons are more accurate and use Dex or Int as the attack stat, but do less damage when compared to heavy weapons which use Str or Con.
• "guns" require that you pay attention to ammo, have longer range, and for light weapons increase accuracy, while for heavy weapons increase damage when compared to "weapons"

Ammo for "guns" is handled with a very simple mechanic: Shoot once per encounter, and you never run out. Shoot many times in an encounter, and at the end of the encounter, you're out of ammo and need to find some more.

Non guns are assumed to have recoverable/easily findable/easily makable ammunition, and so you can shoot as often as you like, and never run out.

Examples:

A sling or a hand crossbow could both be light, one handed "weapons": Dex or Int +3 to attack, 1d8 damage, range 5

A tommy gun or a hunting rifle could both be heavy, two handed "guns": Str or Con +2 to attack 2d10 damage, range 20.

You've made two key changes:

1. Allowing multiple combat half-actions per round
2. allowing movement to be replaced by a non-movement half-action

The primary factors I see are:

• increase in Psyker offensive capability (Most of their offense is more powerful than their allowed weapons; it gets worse under RT or DW, due to a different psychic system)
• decreased access to defenses¹
• decreased emphasis on movement²
• increased emphasis on non-action defense (IE, cover)³
• breaks the equipment bonuses
• decreases incentives to use burst and full-auto autofire modes
• cybernetics and talents with extra half-actions become devalued⁴
• initiative becomes more important⁵
• Ganging up becomes less essential⁶

¹: Since one gets very few defenses per turn, this change of yours makes them less valuable, by allowing them to be overwhelmed faster.

²: The current system makes movement a valuable and essentially irreplaceable part of the round; take it or not, it's lost if unused or unusable. It's not terribly realistic, but is very cinematic. And DH, RT, and DW are all intended to be very cinematic in tone.

³: At present, especially for melee, active defenses (dodge and parry) are quite valuable; cover is less so, but not enough to render it useless. When one allows replaceing movement with a second attack, cover suddenly becomes MUCH more attractive, as it's an assured penalty to be hit, instead of a roll by the defender... but it also reduces drama.

⁴: At present, the only way to get a second attack is expensive talents and/or cyberware with inexpensive talents. If a character can just hole up in cover and double shoot, these talents are far less valuable, making the Assassin and Guardsman's additional combat actions less useful.

⁵: Further, by allowing the etra attacks, you can run a target out of actions sooner, as well, so initiative becomes more important to prevent having actions drained in defenses.

⁶: Ganging up is the great equalizer in RT and DH combats; it's how one overwhelms defenses. Given that every character can defend once for free, and once by aborting, if you can attack twice, you've just eaten both defenses this round, meaning you only need one attack from a buddy to get through. The norm is that you need two buddies to negate the defenses, or one buddy with a multiple attack talent.

It sounds like you made these changes with rank 1-2 characters... it's going to be more profoundly off-norm or higher rank characters, as normal slow growth of actions is made to feel even slower by providing far less of a bonus over not having them.