"On a direct hit, an alchemist’s bomb inflicts 1d6 points of fire damage + additional damage equal to the alchemist’s Intelligence modifier. The damage of an alchemist’s bomb increases by 1d6 points at every odd-numbered alchemist level (this bonus damage is not multiplied on a critical hit or by using feats such as Vital Strike). Splash damage from an alchemist bomb is always equal to the bomb’s minimum damage (so if the bomb would deal 2d6+4 points of fire damage on a direct hit, its splash damage would be 6 points of fire damage). Those caught in the splash damage can attempt a Reflex save for half damage. The DC of this save is equal to 10 + 1/2 the alchemist’s level + the alchemist’s Intelligence modifier."
--you can attempt a Reflex save when you're caught in the splash damage, but not on a direct hit.
Throw Splash Weapon Special Attack
There is nothing in the base rules for splash weapons requiring a saving throw for splash damage or the direct target.
For example, an Acid Flask makes no reference to a save, so there is none.
Alchemist's Fire mentions a save, but only in the context of the direct target putting out the fire condition.
However, specific forms of splash weapons do require saves. For example the Alchemist's bomb says: "Those caught in the splash damage can attempt a Reflex save for half damage. The DC of this save is equal to 10 + 1/2 the alchemist’s level + the alchemist’s Intelligence modifier." So the primary target gets no save (unless you use a discovery that says they get a save vs the bonus effect, some don't allow a save), but the splash targets get a save.
Fuse Grenade says you get a save, but there is no primary target, nor actual splash damage. It just deals its listed damage in the radius.
And finally items like Ghast Retch Flask allow the primary target a save to avoid nauseate, but nothing for the primary or the splash to avoid sickened.
sorry let me try to clear this up im running Iron gods and someone outside my game (not picking on anyone here but a old friend of my is a Pathfinder Society lieutenant idk if i get it form him or not) say the the grenade/rocket launcher and/or grenade if a direct hit that act like alchemist’s bomb with no save even though there a save to them that's what im trying to find out
So lets clarify.
Are we taking about: Grenade Launcher and Rocket Launcher from the Technology Guide?
The Rocket Launcher does not have separate ammo so all of its special rules text is within its entry. Specifically: "A creature that takes a direct hit from a rocket cannot attempt a saving throw to reduce the damage taken. When a rocket strikes its target, it explodes in a 30-foot-radius burst that deals fire and bludgeoning damage to all creatures within that area of effect—a successful DC 15 Reflex save halves the damage for all but the target."
First, there is zero mention of Splash Weapon rules.
Second, it specifies a direct hit on a target, this will require an attack roll (though you can target a grid intersection at AC 5),
Third, it explicitly calls out that a direct hit negates the chance of a saving throw... twice.
The Grenade Launcher basically says that there are more rules in the specific grenades. So lets link them.
Grenades for the launcher. (Also Gas Grenade).
Specifically, "The grenade detonates at the beginning of the wielder’s next turn, hopefully in the area targeted. When a grenade detonates, it damages all targets within a 20-footradius spread. A successful DC 15 Reflex save halves any damage dealt by a grenade."
First, there is no primary targets/direct hits like the Rocket Launcher. Or rather, there is no damage on a direct hit since the Grenade Launcher has no damage value listed. I would argue that this is not very realistic as a baseball to the chest should do some damage. In general when using a grenade launcher, you should aim for a grid intersection because of the much lower AC. However, if you do miss you should follow the splash rules for scatter.
Second, the grenade doesn't go off immediately, unlike most splash weapons (it is similar to a fuse/pellet grenade in this regard).
Third, it explicitly allows a save to targets in the radius when it explodes.
Lastly, both the Rocket Launcher and Grenade Launcher are considered Heavy Weapons with both the Slow-Firing and Touch keywords. Which basically means firing it at all is a Full-Round Action and that all of their attacks (regardless of range increment) are touch attacks.
TLDR: You are both half right. Rocket Launcher direct hit, no save. Grenade Launcher direct hit doesn't matter, always get a save and explodes the next round.