The short barrel is less accurate idea is a bit beat down. I will have to find the article I saw but it was a review of a "suitcase sniper" with a 12" barrel. .49" groups at 100 yards. If the rifle is designed correctly it should be able to shoot accurately even with a short barrel...to a degree. I don't want to see someone try and make a snubnose .308.
The real issue is the ammunition, used in short Barreled Rifles. Unless one handloads specifically for the weapon, Standard Ammo will not have burnt ALL the Powder by the time the projectile leaves the barrel. This causes a significant loss in Muzzle Velocity, and the corresponding Muzzle Energy. It also makes a Heck of a Bright, visual Bloom, at the muzzle.
