Critics of the shorter barrels claim that they not only degrade velocity and increase muzzle flash, but negatively affect accuracy as well. However, such claims are patently false. Barrel length has nothing whatsoever to do with accuracy. After all, short or not, the barrel is still rifled and, as such, will stabilize bullets just as well as if it were longer.
Twenty-plus years of TPR experience has repeatedly shown me that if a given cartridge/load/bullet is capable of, say, ¼-MOA from a 24- or 26-inch barrel, it will still produce ¼-MOA from an 18-, 20- or 22-inch barrel. However, its ranging and penetration capabilities will be reduced correspondingly because velocity is the element upon which they’re dependent.
So, what barrel length is best? Well, it depends upon your mission requirements and what cartridge you select. For urban/suburban missions, where the chance of having to maneuver the weapon around in tight places, there’s really no point in choosing a high-performance cartridge, then using it in a TPR with a barrel 18 to 22 inches long. Better to opt for a lower-powered cartridge, such as the .308 or .30-06. For such missions, they represent a far better balance between performance and user-friendliness.