Are shorter barrels more accurate?

[bwaites]

sorry, said I wouldn't post, so will leave it at this, I believe everyones thoughts on this are different, probably has to be the most asked question, most debated, greatest range of answers and opinions, yet it is so hard to prove since mostly the accuracy is purely in the upper, but I think Clint McKee from Fulton Armory answers it the best:

"
There have been a number of questions lately about looseness of AR-15 upper/lower receiver fit, Accuwedge, etc. Here's my response:

First of all, does looseness or tightness of fit make a difference in accuracy? Maybe, maybe not (how's that for sage advice!). Some say yes, some say it does not matter. In some rifles, it may make a difference, in others, we do know they still shoot well, even though the receivers "flop around."

Personally, I find a rattle trap very annoying, whether it be a rifle, pistol, car, etc. So, at least we do know that the Accuwedge does not hurt accuracy, and eliminates the rattle trap syndrome!

Second, it seems to me that since the sights are on the upper receiver, and you hold the rifle primarily by the lower receiver (pistol grip), that if the upper moves relative to the lower, then the sight picture can move, relative to the hold!

I think this statement is critical. If the sight picture is moving, then all other bets are off. IF the sight picture is the same, I would believe that there is no other issue with sloppy fit.

Thirdly, all the engineers & physicists on this group know that when things can move freely, they will, when subjected to a force. If the upper & lower receivers are dancing all over town each & every time the recoil energy is transferred, then is it not unreasonable to assume that the upper & lower receiver take down pin holes are getting an unreasonable amount of wear from being shocked up & down, back & forth, left & right? The pins are steel & the receivers are aluminum. Guess who loses the battle over time?
"

Free movement isn't always bad. Some shooters have found that free recoil is the most accurate and consistent way to shoot some rifles. Yes, the pin holes will wear out, but that takes a LONG time in most cases. I've seen uppers and lowers with 20,000 rounds on them, and they still functioned properly. JP talks about some rifles that he has built that have 40,000 plus rounds through them, with the same barrels that still shoot sub MOA!

All that said, I don't like rattles!