In all honesty, there isnt much room to improve the actions of modern assault rifles. There are dozens of post-stoner improvements that have bern tried. Millions have been spent on them. They have all been shelved as to complex or cumbersome. The gas-operated rotating bolt is so elegant, so reliable, that fundimental improvements are hard to imagine.
Adding water to the equation? Rust, mud, weight, boiling ... you would need some radical improvements to justify such added complexity.
I suspect there should be a lot of room for improvements, just that we are not able to perceive them without first- or second-world war going on.
I remember reading about importance of a newfangled barrel free-floating construction on carbines, soon after the Afghan war started. The examples used at that time were kludgy top-rail secured things supposedly used by mysterious SEALs guys. Later I saw Crane stock for the pair of chemical lights.
Today, those are slim M-LOK with rail on top and secured to the barrel nut, HEL-STARs, and MOE SL stocks. Oh and Russian Army standard infantry rifles are now cheap AKs with f*’ng buffer tubes, and G36 now has short aluminum mounts to avoid floppy carrying handle issues(“polymer degradation” fiasco).
What caused all those changes were clearly the wars.
Adding water to the equation? Rust, mud, weight, boiling ... you would need some radical improvements to justify such added complexity.