few word about volume ratio, i dont think is that important, i have a vsr with a 360 mm 6.08 barrel and a aps 2 system vsr abomination with a 455mm and 6.02mm. guess what? both can hit human sized target at 100m, with the aps 2 one i shot at 110m at same target with 0.5g bb. target was a 1/3 steel barrel (was cut on vertical for some reasons)
also i have 1J aug with a 505x6.08mm barrel and could not see any difference when compared with other aeg with much "better" ratio. also it more quite, all i did is installed a cheap ass silent piston head.
from my experience chasing long range, most important thing is BB weight, joule of course, stability of hop up ( can be made of plastic and be great, most important thing is to not have wobbling parts) and of course buckling, r hop, g hop, j hop, decepticon or other r hop like would do it, perfect airseal, tight barrel, for better air efficiency, no need super strong spring, with will help with noise and reliability. and if you can go for the greatest air volume, less strain on component coz you will use a weaker spring and lower noise level. and remember the most important thing in archiving long ranges are weight of the BB, you can have spacecraft level of component without heavy bb they will do nothing for long range.
Here is the thing. The BB is being moved by air from an air pump, there needs to be a certain amount of air, and a certain amount of pressure to adequately have the BB to overcome the first portion of Newtons 1st Law “a body at rest will stay at rest”; too little of either volume or pressure, and the BB will not have the proper energy to convert enough of the potential energy to kinetic.
The primary means to give the proper amount of air volume and pressure is tied to the cylinder to inner barrel ratio in relation to the BB weight. With the proper ratio, the air pump is its most efficient, requiring the least amount of external force (the spring in this case) to give the desired energy output from the BB at the muzzle.
If an air pump is using less than the needed amount of cylinder to inner barrel air, all things considered equal, greater external force is needed to push the air in a manner to meet the kinetic energy output. This is exactly why short stroked or DSG/TSG AEGs need a really high spring rate (M160/M170/etc) to put the same joules out that a full cylinder and full SSG AEG can do with a M115/M120. Conversely, too high of a ratio results in a popping sound, but can be remedied by using a slightly less potent spring.
Using a higher rate spring requires more energy from the motor/battery/gears; or more energy to pull the bolt back; it also has a heavier object (the piston assembly) to be moving at a higher level of kinetic energy, which puts a strain on the air pump at the end of the pistons travel. In both manners (energy to pull the piston assembly back, or the pistons higher kinetic energy impact), the system is being put under stress that will add to wear and tear, as well as sub optimal performance of the cycle time (AEG : trigger response, BASR effort to pull back the bolt and the probability that the motion will move the barrel more from the aim point).
The best means of comparison is having two engines (#1 600cc, #2 1800cc) each propelling one 3,000 pound car that is the same design to a speed of 100 miles per hour in the same amount of time. The 600cc engine will need to rev at a significantly higher RPM in order to do the same work as the 1800cc engine will; the 600cc engine will operate with far less efficiency than the 1800cc, the stress on the engine will be greater in rotational forces, frictional and EGT heat, fludic and combustion air pressures , not to mention vibration of the engine.
If there really wasn't a big advantage of following the cylinder to inner barrel volume ratio for a BB weight, we would all be using AEP gearboxes, yeeting .66g ceramic BB’s 350 feet, with barely any battery drain or stresses on the gearbox.
Physics is a thing.