That outlandish "theory" has about the same validity as man-made global warming and other religions based upon junk science. It is a shame that otherwise reasonable people accept such nonsense.
Maybe and maybe not. My old Mini-14 was pretty accurate right out of the box. When I put on an aftermarket flash hider, it shot like crap. When I removed it, it shot well again.
The only explanation I have is that the flash hider changed the barrel resonance. Maybe you have a better one.
Try using a good tone wood.
Works for guitars *shrugs*