It's a sci fi weapon. This is super-tame compared to plasma guns, laser rifles, and micro-missile launching smart guns. You might check with a gun smith, who'll tell you they can't make it now. Otherwise, the rest is invention and engineering. Is the ejector on it for clearing jams? It is caseless, so no brass. Hard science seems like overkill.

@DWKraus: Yes, the ejector is their for clearing jams.

The text on the pic is too low-res to read, is it important?

I'd drop the hard science, leave reality check. I think you have your 3r burst and full auto rates switched.

@DWKraus: That I do! My bad

@Draft 85: Not for this discussion, but if you want I can type it out

And yeah, I guess theh could have solved the problems and put horisontal mag in there, in that 2210, heya guys what have been u doing all those 2 centuries, eh?

@MolbOrg: soldiers wearing this has exoskeleton armor. Recoil isn’t a concern to them

Then rework the gun system fully, feed it from exo, and then u can solve caseless problem, by just basicaly feeding gun powder pelets and bullets a modern version of muzzle loader, but this will be rear automatic loader. But then the rifle composition has to be reworked completly in part of feeding. Stock also seems of a little use, if it isn't part of that new feeding mechanism. As for u q - they may or may not come with better compoinds for caseless, but there is no way to tell, as we didn't comeup with good stuff, and reworking loading system may change situation, as it gives more room for

As long as we're decoupling powder and projectile, why not be really futuristic and use a light-gas-gun? Handwave a few engineering issues, and exploding gas cartridges are more myth than reality. en.wikipedia.org/wiki/Combustion_light-gas_gun

Worth noting the army gave up on three round burst when they found out it did nothing, It is only helpful if you have large numbers of untrained wielders. Otherwise it just wastes ammunition.

180 billion infantry rifles makes no sense, unless they are intended to be discardable single-use items.

Some issues I see: the magazine well design is wrong. Try to fast change a magazine with such an angle and you will be forced in an awkward movement. It should be either straight or slightly inclined forward. The cheek rest does not seem to be able to slide back but you may need more distance from the eye to the lens of a scope if you mount one. Elaborate on the "6.8x31mm caseless cartridge". You ask about it but without providing details on how the system would work. Also show the ammo as it affect the magazine design. 180 billions units seems a tad too much :) (maybe you meant millions?).

@Duncan Drake: This weapon is used by a interstellar nation with a population numbering in the low trillions.

@DTCooper how can there be a human population of trillions in less than 200 years from now? Unless a large part of that population is alien of course. But then it's hardly likely their anatomy would happen to adapt to the weapon comfortably.

@Duncan Drake: What do you mean how? The same way populations have always grown, dude

@DTCooper can't do the math right now but from 7B to 'trillions' (at least 2000B) in 200 years seems impossible. Anyway it's your story -.- Ah, please refrain from calling random people online "dude". Some perceive it as confrontational.

Skip the trigger. That's a primitive device - it slows down the use, adds jerk, and is mechanically imprecise (can fire at various micro positions). Touch pad, neural link, eye blink, any number of alternatives would be better by then

Optionally, skip the sight. Why would you require a user to hold their eye in a specific place, and be mostly blinded to external vision in a fight. You'd have a computer stabilised display instead, with zoom crossbars for accuracy. If its closer quarters you can hold the weapon lower and glance down at the sight, or have the sight superimposed on a heads-up display, along with normal vision.