The first thing I want to say is that combat is not meant to be the focus of the game. Characters have a limited number of hit points and die easily, so things that can get you dead are common and to be avoided. That said, combat will probably still happen sometimes, and it's still a very dramatic and exciting part of the game.
Science fiction roleplaying games have a tendency to become weapon fests -- pages and pages of weaponry to choose from. This is because with greater technology comes a wider range of possible weapons. In fact, because the possibilities are so tremendous, I'm just outlining some basic guidelines for weapons. If you are given a weapon, I'll give you the statistics for it. If you want to choose a weapon yourself, talk to me and we'll work something out that fits your taste and my idea of the game universe.
In a space opera type universe, ranged weapons become key. Laser blasters rule (there are the Star Wars lightsabers, but those don't seem to appear in the Hub stories -- not that somebody can't have something of the sort; I'm sure the tech exists). Hand-to-hand combat is simply not as common. That said, there may well be situations where hand-to-hand becomes important -- for example, a psi teleports the guards' guns out of their hands, and the party's hand-to-hand combat expert leaps into action.
For any projectile weapon the important factors are the damage, range, ammunition capacity and type, and rate of fire. Secondary considerations include the weapon's weight and recoil.
In general slug-throwing weapons will do d8 per bullet, charged-needle weapons do d10 per hit, and pure energy weapons do d12 per hit. This may vary with the individual weapon, though. I mean that a slug carbine or rifle may do d10 or even d12 depending on the power of the chemical reaction or other process propelling it.
Ammunition is divided into bullets, needles and energy packs. Of course, there are different calibers of bullets, needles come in the damaging and stunning varieties, and energy packs are not standardized between weapon types (someone with some ranks in Technosavvy might be able to jury-rig an energy pack to work on a different weapon than the one for which it was manufactured).
Range is somewhat problematic, but I would say that a typical slug pistol probably has about a 30-meter range, a slug carbine a 50-meter range and a slug rifle somewhere around 70 meters. An automatic version of anything has a slightly smaller range. Now one would expect needle weapons to have about the same ranges as slug weapons, and energy weapons to have somewhat greater ranges (but not a lot, because part of the range consideration is accuracy rather than a limitation of the projectile).
We're dealing with rate of fire in this game by stating how many rounds of ammunition can be fired off in a single melee round. (These two meanings of the word "round" are going to drive me insane yet.) Many weapons fire only once per round, but some are capable of three-round bursts or more. Some weapons have multiple fire modes; you can fire one shot or a three-round burst. In that case it's your choice.
Thrown, bow-type and chemically-propelled slug weapons aren't likely to be dealt with much, frankly, but we can use the D&D values for the low-tech ones.
I can imagine that there might be weapons made to propel heavy slugs using other than chemical means. If you have an idea for one of these (linear-induction mass-driver rifle?), we can work on it. We can add a bonus to the damage done or switch to the next higher damage die, and probably keep the rate of fire low.
Most of the weapons mentioned in the Schmitz stories seem to fire either energy-charged needles or pure energy bolts. As is the way with "good" science fiction, the emphasis is not on spending pages and pages explaining the technology but rather on moving the story along. That does mean, though, that a lot of this is interpretation.
The advantage of energy-charged needles is that the projectiles take up very little space and therefore a clip can contain a large number of them; the energy packs for these weapons can provide more shots than a purely energy weapon. But the disadvantage is that if you run out of either one the weapon is useless. An important thing to mention about charged-needle weapons is that they can be stunners; a different type of needle is used that does adjustable subdual damage but uses the same energy pack.
Pure energy weapons (it seems from the stories) do only deadly damage and require only energy packs. There are also stun beams, but in the stories they only appear off-camera, and the example I remember best is ship-mounted. If somebody wants a hand-held stun beam I can work something out, though (I'm thinking d12 subdual damage on a hit, but continuous beam fire could be treated like any beam weapon -- see below).
Weapons capable of firing multiple-round bursts and continuous beams are obviously going to do more damage in a round. Since people are basically creating their own weapons, we'll deal with this on a case-by-case basis, but here are some guidelines: I would imagine that a three-round burst weapon would have a +1 attack bonus and 1 extra die of damage, while the maximum 100-round-per-melee-round weapon would have +10 for an attack bonus and 10 extra dice of damage. A continuous-beam energy weapon would probably have bonuses comparable to the 100-round weapon. Note that continuous-beam and super-automatic weapons like these eat ammo like popcorn.
Low- and medium-tech weapons are almost unheard of in most of Hub society, though there are planets where such things are more common. One exception to this general rule is Open Hand, which most military trainees learn in the event that weapons aren't available or run out of ammo. Of course, there are esoteric societies that train with low- and medium-tech weapons as martial arts (I can certainly imagine martial arts based on ancient slug weapons, though they don't show up in the Schmitz stories).
Low-tech: Open Hand, Blades, Blunts, Bows, Thrown
Medium-tech: Slug-Throwers
High-tech: Charged-Needle Weapons, Energy Weapons
General: Pistols, Target Pistols, Carbines, Rifles, Automatic
Unless a character has had special training, she is probably not proficient in target pistols, carbines, rifles and automatic weapons. However, more or less every citizen of the Federation knows how to use a needle pistol or an energy pistol. They probably have pistol target shooting classes in public schools. See the character classes for what proficiencies come with a class. For the more exotic profiencies you may have to take a Weapon Proficiency feat to get them.
Note the separated nature of proficiencies: in order to be able to use a charged-needle rifle without penalty, you need Charged-Needle Weapons and Rifles. As a more exotic example, if you had some kind of lightsaber-like energy blade, you would need Energy Weapons and Blades to be able to avoid the penalty.
The Automatic proficiency is separate because firing an automatic energy carbine is not the same as firing a non-automatic energy carbine. Definition for the sake of this game: to fire more than a 5-round burst without the -4 non-proficiency penalty to hit, you must have the Automatic proficiency.
As an example I will detail Trigger Argee's famous Denton pistol. The Denton is a charged-needle target pistol with both damaging and stunning needles (meaning there are two clips containing 50 needles each). It fires only single-round shots (d10). It has a variable-stunning ability: when firing a stun needle, the player can declare a cap for the stun damage before rolling and thereby achieve some measure of control over how long the target will stay stunned. The energy pack contains enough power to fire 100 shots. The Denton is a rather small weapon, weighing only about 1 kg and easily concealable. As a target pistol it has a longer range than a typical pistol; I would say 50 meters.
The usual D&D rules apply here -- get damaged to zero hit points and you fall unconscious; below that, -10 means you're dead; in between you lose 1 point per round unless somebody stabilizes you or you make your Constitution check to stabilize on your own. However, since you don't get hit points with increasing experience, you also only heal one hit point of damage per day on your own if you remain active, though if you have a Constitution bonus you can heal that many points per day if you rest and twice that if you take complete bed rest.
However, this is the Federation, and there is advanced medical technology. You can be fixed up pretty quickly by techniques and devices that basically convert regular damage into subdual damage (meaning that you may well be unconscious after the process until you recover). A fully-functional hospital can do this with 10 points of damage per 10 minutes. A medical robot can convert 5 points per 10 minutes. A portable first-aid kit can convert 2 points per 10 minutes, though if another person assists and makes a Heal check, this amount can be increased.
Subdual damage works the way it does in D&D, but if you don't remember here's a refresher: it heals by itself at a rate of 1 point per hour (plus your Constitution modifier, if it's greater than zero), and if your subdual damage is ever greater than your hit points, you are unconscious.
Example: You have a maximum of 8 hit points and take 5 points of damage when you are shot with a needle pistol. Ouch! You are now 3 hit points from unconsciousness. Fortunately you get away and make it to your ship's med bot, which patches you up, turning those 5 points into subdual points in 10 minutes. Now you are fully healed, but have 5 points of subdual damage; being shot again right away would likely send you into unconsciousness, but otherwise you are OK. In an hour the subdual damage will decrease to 4, and so on until you're fully recovered.
Example Two: Somebody hits you with a three-round burst from an energy carbine and you take 12 points of damage, and you go down! But you're in luck; that could easily have killed you outright. You are now at -3 hit points and are now unconscious. A round goes by before another party member gets you to the med bot, meaning that you've gone down to -4 hit points. But the med bot heals 5 points in 10 minutes, bringing you up to 1 hit point, but you now have 5 subdual points, meaning you are still unconscious. In the next 10 minutes the med bot brings you up to 6 hit points and 11 subdual points -- you're still unconscious. In the third 10 minutes you are fully healed at 8 hit points, but you now have 13 subdual points. You will have to rest for 5 hours before you wake up (less if you have a higher Constitution), but you are lucky to have survived a hit like that!
There are only two times I can think of that spacecraft face off each other in the Hub stories ("Legacy" and off-camera in "Glory Day"), so it's difficult to gauge what typical starship combat is like in the Federation. There are force fields, but they don't seem to be used to protect ships from attack (perhaps they're not practical for that). I would guess that energy weapons would be the weapons of choice except at extreme close range. A ship-mounted stun ray appears in one case, but I get the impression that such a tactic doesn't work well except on very small ships. Mostly I'll be dealing with combat between spacecraft as we go.