They don’t really translate from conventional firearms at all. Blasters in Star Wars are effectively plasma weapons. They fire ionized gas into the victim. In theory this should result in localized burns on the victim, destroying pretty much anything organic they hit, and melt most inorganic material on impact.
In the films, blasters are pretty inconsistent. They’ll sometimes burn through hull plating and kill in a single shot. Other times they’ll fail to damage delicate cybernetics beyond burning off the prosthetic skin or simply injure someone.
Here’s the thing, this isn’t a world building consideration, it’s a writing problem with the films. Like the guns in many works of fiction, Star Wars’ Blasters run on the power of plot.
It’s also part of why Imperial Stormtroopers can go from being incredible marksmen off screen, to sort of spraying in the general direction when the cameras are actually rolling. At least, without having to assume Obi-Wan is just being incurably sarcastic. (To be fair, Obi-Wan is always incurably sarcastic.)
Generally speaking, as a writer, you want coherent rules driving your setting. This helps you nail your setting together, and present a consistent world for your audience.
While it might seem like writing out the rules for your world is restrictive, it actually offers a lot more leeway to you. When characters in a setting with poorly articulated, or inconsistent, rules exploits an idiosyncrasy it’s a plot hole. The most infamous example is probably the increasing “technobabble” in later Star Trek series. When characters in a setting with concise rules the reader understands exploit an idiosyncrasy, it’s being clever.
One of the unique challenges for fan fiction writers is you’re forced to extrapolate the rules for the setting from the available material. Star Wars is an easier example, because the setting has been very heavily detailed over the years, and you’re left with more of a question over which parts of the canon you’re willing to include and work with.
This is less of a problem when you’re writing official tie-in work. In cases like that you should be provided with a style guide and a setting bible. Ideally, these will tell you how the material should be presented, and what the rules for the setting you’re working on are “supposed” to be. In practice, this doesn’t always happen, and the results when the writer is kept in the dark can range from amusing, to fan rage inducing.
In theory, blasters should have a specific way they work, but in practice (from a writing perspective) they’re a clumsy and random element of Star Wars.
They should cause severe burns on impact, burning through the victim. It wouldn’t be necessarily lethal, this could potentially only incapacitate, but it would kill more often than not.
Blaster bolts should burn through most inorganic matter on impact. It makes sense that hand weapons wouldn’t be able to burn through hull plating rated for reentry. So, carbon scoring isn’t that strange, in context. Though it does create a bit of weirdness with astromechs. These are actually expected to be exposed to reentry friction, so it makes sense that they’d be able to survive a direct shot from a blaster, or they wouldn’t be able to survive reentry in any fighter with an exposed astomech socket.
Imperial E11 Blaster Rifles have a stun setting… because that makes sense somehow. Star Wars does have stun weapons (several, actually, including Neural Inhibitors and sonic weapons), but they’re distinct from Blasters, and by necessity would need an entirely separate firing mechanism, so it’s a little strange that this is bolted on there for one scene and then never used again, except because the power of plot compels them.
Incidentally, the E11s in A New Hope were actually firing blank 9mm rounds. The props were functional Sterling Mk IV submachine guns with random bits bolted on to make them look more impressive. I can’t remember if the shell casings were digitally removed for the Special Edition remastering, but they were visible in the pre-90s versions of the film.
In theory, magnetic shielding makes sense. One way to keep plasma where you want it is through the use of magnetic shields, so it would follow that the blaster bolts themselves are carried by a magnetic envelope of some sort. This might also explain why capital ships are dependent on turbolasers, because any magnetic shielding would, by necessity, make it impossible to use blasters offensively. This might be part of why personal shielding is such an oddity in Star Wars. But, this is another case where the terminology is a little strange.
It’s also worth remembering that there are other varieties of firearms in Star Wars. Off hand, there are disruptors (beam weapons that disintegrate the victim at a molecular level), and slugthrowers which are conventional ballistic firearms. There are also exotic variants like the Wookie Bowcasters, or Concussion Rifles.
If you’ve never read them, I strongly recommend reading the Thrawn trilogy by Timothy Zhan. Zhan did a lot of work knitting the original films together into a coherent setting, and laid groundwork for the larger Star Wars setting that’s still filtering into the new films. Some of the material has been ejected, both by the prequels and by the new Disney, but if you’re wanting to work with Star Wars, this still is the place to start. It also features, probably, the single best villain from Star Wars as a whole. The books aren’t perfect, but they are seriously, worth reading.