Run & Gun returned capsule rounds to Shadowrun. They inflict a small amount of stun damage on a hit, but splash their chemical payload on even a grazing hit. This actually makes them more likely to deploy their chemical payload than a dart gun when dealing with armored targets, as long as those targets don't have chemical protections. Their primary downside is their poor range, being limited to light pistol ranges regardless of the weapon you fire them out of, which does mean the dart-gun-rifle is still useful for tranq-ing guards at long range. A minor issue is that the capsule rounds are still explosively propelled bullets. Dart guns, depending on your GM, might be considered silent by default, or at least less noisy than bullets. Of course it's easy enough to use a silenced gun.
The fun, in my opinion anyway, is all the interesting combinations you can get into a capsule round thanks to the addition of DMSO in Stolen Souls. Any Injection vector chemical payload is now viable for use in the guns you already carry for shooting people.
Narcroject is by far the most obvious choice for basic take-downs. It's 15 power stun is great, but it's main feature is the instant effectiveness. Unlike Neuro-Stun, you don't have to wait 1 combat turn for the chemical payload to circulate through the blood stream. It's also cheap and not too hard to get a hold of.
LAÉS (Stolen Souls), and it's weaker variant, isn't so fast acting, but it's memory erasing features can be very useful, and kicks in even if the target isn't knocked out, and explicitly covers the dosing event. Because it's a paint ball like splash instead of a dart, DMSO capsule rounds may be a very effective way to deliver the this at range. A dart would leave more of a trace. I actually like the idea of this drug loaded into capsule rounds in an implanted gun for a face or social intrusion specialist. If you get caught doing something you shouldn't, you can quickly shoot your target, and a few seconds later they won't remember what's going on, or what they say you doing. "You got some sludge on your shirt there. Here let me get that... say you don't look so great. You feeling ok? Maybe I should just let you get back to work here. I'll show myself out."
Slab (Stolen Souls) is slower acting at 2 combat turns, but it's power 16 makes it slightly more potent than Narcoject. It's main feature is the death-like hibernation effect. Maybe not especially useful in a ranged weapon where knock-out chemicals would work just as well and faster, but interesting if your objective is fake someone's death, especially if combined with Murder Armor. Using Capsule rounds means you're still firing a real gun with real gun noise/look, something not true of dart guns or a squirt gun. It's also a useful one for faking a medical emergencey. Shoot the target with a slab capsule or two, and a two rounds latter you can be calling in an ambulance to take the target out. Because slab is hard to detect vs actual death, this is a good option for targets with biomonitors you need to trick.
We don't yet have the rage-inducing K10 drug yet, but shooting a target full of drugs already in 5th edition could have interesting options. While in most cases a knock-out toxin will work better for disabling a target, if your objective is to mess a target up before a big meeting/event, then dosing them in a hyperactive stimulant or any of the drugs that would reduce charisma or social limits is an interesting idea. Hell, even a psychedelic would likely mess with a target's ability to carry out a negotiation or press conference. If you time it right, Novacoke's side effects when it wares off (Charisma & Willpower 1) can be useful.
GAMMA-SCOPOLAMINE isn't accessible to players at character creation, but it's paralysis effect and immediate onset makes it's an amazing option for disabling targets quickly. The downside is that it doesn't knock the target out, so they may still observe you. Much like slab, it can work great for faking a medical emergency. Carrying a disabled, but "awake & cooperative" target out on gurney may look better to suspicious guards.
