Practicality of Mass Effect's Firearms.

ME's firearms aren't practical at all. The whole complex mass accelerator stuff would be so complicated to maintain, I'd expect. Although they are mass produced so much that it might not be so bad.
And it gets worse when the third game established that swords are more effective than bullets in the ME universe apparently, so all that technology is pointless.

To answer the original post, I am not a gun enthusiast (I don't actually know all that much about guns) but if I had to answer your question, I will have to break it down by game, since the lore changes a bit between them.

Modern guns versus Mass Effect 1 guns:
Modern guns need be reloaded and each gun can require different ammunition. The amount of spare ammunition you can carry is limited.

ME1 guns have practically unlimited ammunition*. They do not need to be reloaded; rather they can overheat, at which point you must wait until they cool down before you can use them again. Certain mods allow you to reduce the heat buildup; it is possible to mod your weapons so they never overheat, allowing you to fire almost indefinitely.

* Note that weapons in the Mass Effect universe do not have unlimited ammunition. Rather, most of the weapons chip off ammunition from an internal block. This block can eventually be exhausted. This lore was probably created to serve the gameplay, but it carried through all three games.

ME1 guns can be jammed by a someone else with an Omni Tool (Sabotage power).


ME1 guns probably come out on top over modern guns. You, or an enemy would need Sabotage to even the odds.


Modern guns versus Mass Effect 2 guns:
Guns in Mass Effect 2 no longer overheat. Rather they use heatsinks. This requires you to 'reload the weapon' by replacing the heatsink. Lore-wise, this was done so that guns can deal more damage, and with good reloading can still improve damage-per-second over the old overheat mechanic. This lore was probably created to serve the new gameplay mechanics, an improvement in my opinion.

ME2 guns essentially use ammo now, but all guns use the same ammo (heatsinks). ME2 guns can still be jammed by someone else using an Omni Tool (Overload rank 3), but only Shepard and his squadmates appear to have this capability.

ME2 guns still come out on top over modern guns, unless no heatsinks are nearby or you have a really good Overload. It is unclear if you can re-use heatsinks if they were to cool down; I do not recall if this was mentioned in the codex.


Modern guns versus Mass Effect 3 guns:
Mass Effect 3 guns are a weird mix of mostly heatsink-based guns with some ME1-style overheat-based guns. The Overheat-based guns break the lore established in ME2 by dealing more damage than some heatsink-based buns. And at least one gun (Reegar) is heatsink-based but does not appear to use an ammo block.

ME3 guns no longer appear to be able to be jammed by another person; no Sabotage or Overload can cause the weapons to overheat.

ME3 guns likely better than modern guns. The Avenger is only deadly in cutscenes.

The reason I ask this is because with the guns in ME, they seem very very complex internally, having all sorts of electronics to shave off bits of a solid metal block and act like mass drivers, with other electronics to help make sure that shooting it on a sunny day isn't different from a rainy day. I like these types of firearms from an engineering standpoint, I'd want to take one apart to see how they work, but from a practical standpoint, an M4A1 or AK-12 seem much more practical, they are simple and reliable. It's kinda like how I feel about the AN-94, it's really cool how the gun achieves it's "Hyperburst" (Wherein the gun shoots two rounds at 1800 rounds per minute), but if I were to clean the gun, I would find it to be a nightmare.

Yeah, trying to figure out how this would actually "work" in real-life would be interesting, but of course it relies on "mass effect", which is based on the fictional Element Zero, which forms the basis of the technology in the Mass Effect universe.



But that being said, consider that history shows improvements in military technology may not be practical from a creation and maintenance standpoint, but its overall effectiveness makes it much more practical:

1. Bronze -- and later iron -- weaponry is harder to make and maintain than wood and stone weaponry, but it ultimately more useful and effective, therefore more practical.
2. Gunpowder and early firearms (muskets, cannons) harder to make and maintain that iron weaponry, but ultimately more useful and effective, therefore practical.
3. Improvements to firearms to the point of assault rifles, bazookas, tanks, battleships, fighter jets, and so on, are again harder to make and maintain than early weaponry but are more effective, therefore more practical.

In the Mass Effect universe, technology progressed to the point that 'Mass Effect weaponry' are probably harder to make and maintain than our more modern weaponry, but are ultimately considered more effective, and are therefore more practical.

Or maybe I am just talking out of my ass here.

I actually did have a small discussion in the ME:A General discussion of BSN. About if you were able to go to another star system, FTL of course, would you go and what would you bring. For me, I'd bring something like the arctic warfare magnum due to it's high stopping power, range & accuracy (It made a former longest sniper kill in history), and it's bolt action would allow for more ammo efficiency, which is useful if you were light years away from a gun store with .338 lapua magnum ammo.
Another option would be a Steyr Scout


The reason behind this would be, again, bolt action=ammo efficiency, but's it's also lightweight, about 6 pounds unloaded, uses a common rifle cartridge (.308 winchester), has an integrated bipod, has an extra magazine in the stock, a low magnification eye relief scope, and is built to be an all purpose rifle.