the group size performance. It does degrade faster with the 16", but the difference between the 16-20 isn't significant till past 800, and both still start to suck then. the dropoff is pretty rapid, just a little faster with the 16. Lets put it this way, I put a 20" on mine for the same reason, and i'm perpetually thinking about dumping it for a 16, or even a 14.5 with a pinned muzzle brake. I likely will never shoot past 500, and at that you can't tell the difference, in reality due to barrel whip the 20" could be worse than the 16". But that's a long story. Basically though if you take a heavy barrel 16" that weighs the same as a normal profile 20", the 16" is more accurate for at least that first 500 yards, probably still is close to 700.