The human factor (follow through, NPOA, etc.) becomes more important because of the design of the system. The development cycle for the rifle was to create the lightest weight reliable (safe) bullet hose possible with accuracy that is acceptable for infantrymen. What most people on this site are doing, is asking for a lightweight bullet hose to do precision rifle things.
Every adaptation, fancy upper, new barrel mounting system, handguard, etc. has been a series of bandaids to cover up the root problem. The AR system is not rigid where it counts. All forces from barricade resting, bipod loading, etc. result back directly where the barrel is mounted into a thin-walled piece of aluminum tubing. The barrel is clearance-fit into said thin wall aluminum tubing, and how tight/rigid it is held in place is based off of torque on a steel nut over aluminum threads. Insult to injury is the lock time of a large swinging hammer, parts that have to "float" with clearance for semi-auto function, etc. The gas system is a flimsy little tube mounted to a barrel that receives a significant vertical thrust when gas escapes through the gas port... The whole thing is less rigid, more clearanced, and exposed to a series of dramatic forces that a bolt action never sees. There are thermo-fit uppers, thick-wall uppers, adjustable gas blocks, faster lock time hammers, etc. All are bandaids and while they help, they do not completely bridge the gap to bolt-gun land.
Contrast this to a bolt action where you have a thicker receiver, made of a material with 3x the modulus of elasticity, with a barrel threaded directly into the receiver, torqued to a similar or higher value, mounted in a stock/chassis that creates a layer of isolation from the forces applied to the stock/bipod/fore end, and with a striker assembly that has much reduce lock time, trigger pull weight, etc.
My experience a couple years ago (2nd place bullet for the season in PRS gas gun) is that if you do everything almost perfect and test it to death, you can get 3/4-1MOA for 30 shot strings, but there's a laundry list of components, settings, etc.. that each one individually has the capacity to take your raw system dispersion from 3/4-1 MOA and make it 1.5-3 MOA. That's just the system, no shooter error. Now add shooter error, position, follow through, etc.. and it gets much uglier in a hurry than what you'll see with a bolt gun. Things as small as bipod vs. bag for a rest produce .1-.4 mil vertical shifts. Uneven bipod footing produces horizontal shifts proportional to applied loading (as much as .8-1.0 mil).
1. The system is flimsy and more subject to giving larger dispersion by default
2. The system being flimsy and having a longer lock time is MUCH more subject to getting wild with poor fundamentals and "forcing" shots.
Shooting gas gun at a level that I was in the running for top gas gun for the season I'd place 50-80th place in a typical PRS match. When I shoot a bolt gun and keep my shit together I'm a top 25 shooter most of the time, often enough top 10. You can tell me I suck at shooting but I've done enough testing to confidently say gas guns don't have the physical dispersion capacity that bolt guns do. They are not the same from the start, and poor fundamentals will only exacerbate the problem.
