As in, use it in a sling? My initial reaction is to say no, but after browsing some forums, instead I'll allow it with the following concerns/caveats:
Using it in a sling means you can't move if you want to reload and attack.
I will impose a -4 improvised weapon penalty on attacks. Reason being, these lines from the Sling Weapon itself:
[ +- ] Sling
Source Ranged Tactics Toolbox pg. 0, PRPG Core Rulebook pg. 142, Ultimate Equipment pg. 17
Statistics
Cost — Weight —
Damage 1d3 (small), 1d4 (medium); Critical x2; Range 50 ft.; Type B; Special —
Category Ranged; Proficiency Simple
Weapon Groups Thrown
Description
A sling is little more than a leather cup attached to a pair of strings. Your Strength modifier applies to damage rolls when you use a sling, just as it does for thrown weapons. You can fire, but not load, a sling with one hand. Loading a sling is a move action that requires two hands and provokes attacks of opportunity.
A sling fires sling bullets. You can hurl ordinary stones with a sling, but stones are not as dense or as round as bullets. Thus, such an attack deals damage as if the weapon were designed for a creature one size category smaller than you and you take a –1 penalty on attack rolls.
Rationale: If rocks are so dissimilar from sling bullets, alchemists flasks,
especially home made ones, are in a different category altogether.
That being said, calling back to an older conversation, my research led me to these:
I knew there was something like that![ +- ] Flask Thrower
Cost 25 gp Weight 4 lbs.
Range Increment 20 ft. (thrown)
Category ranged Proficiency exotic
Weapon Group thrown
This staff has a cradle at the end, designed to hold alchemical weapons such as acid. A flask thrower significantly extends the range of thrown substances that deal splash damage, such as acid, alchemist’s fire, or holy water, as well as that of tools such as tanglefoot bags, thunderstones, or caltrops.
[ +- ] Sling Staff, Halfling
Cost 20 gp Weight 3 lbs.
Damage 1d6 (small), 1d8 (medium) Critical x3 Type bludgeoning
Range Increment 80 ft. (projectile)
Category ranged Proficiency exotic
Weapon Group thrown
Made from a specially designed sling attached to a short club, a halfling sling staff can be used by a proficient wielder to devastating effect.
Your Strength modifier applies to damage rolls when you use a halfling sling staff just as it does for thrown weapons. You can fire, but not load, a halfling sling staff with one hand. You can hurl ordinary stones with a halfling sling staff, but stones are not as dense or as round as bullets. Thus, such an attack deals damage as if the weapon were designed for a creature one size category smaller than you and you take a –1 penalty on attack rolls. A halfling sling staff can be used as a simple weapon that deals bludgeoning damage equal to that of a club of its size.
Loading a halfling sling staff is a move action that requires two hands and provokes attacks of opportunity.
Halflings treat halfling sling staves as martial weapons.
