I plan on buying an AR-15 at some point, at the moment I am just doing research trying to figgure out what the best configuration would be.  I am wondering about barrel length.  I know there are 14.5" barrels, which have permanently attached compensators that bring them up to 16".  That idea seems rather pointless to me, why not just get the 16" barrel?  Then there are also 24" and 26" barrels, but that just seems so long and unwieldly.  

Basically my decision boils down to 16" vs 20" and I would like to know if one is considered more of an appropriate barrel than the other, as far as accuracy and velocity.  Is the 16" significantly less accurate than the 20"?  Does the higher velocity achieved by the longer barrel significantly affect performance?

Thanks

As I understand it not until the bullet
is 500yds. or more out and it is insignifigant
before that.

I shoot better with a 20". Don't forget that once you have an AR lower, you can acquire additional uppers in different configurations without the hassle of going through a dealer. So you can have both a 20" and a 16" rifle. Or even add a 24" at some point.

All things being equal a shorter barrel does not neccessariy mean less accuracy.  They (you know, who ever "they" is) say that you gain around 50'/sec. for every inch of barrel.  This will mean roughly 200' per sec. more with the 20" tube.  This will translate into a flatter trajectory and result in more hits at longer ranges with less sight adjustments.

I have everything from a 14.5 shorty AK to a 24".  I like the 14.5/16 carbine size the best.  Easiest to handle and the most fun to shoot.

Remember, length = velocity = greater effective range.  It's not really a matter of accuracy, it's about effective range.

[img]http://www.bushmaster.com/images/faqchart.gif[/img]

Thanks for the info.  It looks like 16" is a good place to start.  Now can anyone explain the difference between the Bushmaster 16" "free floating" barrel on their V Match Rifle, and 16" barrel on their A2/A3 rifle?

Free Floating is exactly what the name implies - the barrel is floating free of pressure from the handguard.  This is done to relief pressure from the barrel and is most effect when shooting with a tight sling, which can pull the barrel off target.

Bushmaster offers 2 ways to achieve this - their DCM/CMP model and the Vmatch rifles.

DMC/CMP - these are 20" barreled upper with a specially modified handguard that looks milspec on the outside, but is modified so it is suspended from the barrel nut and doesn't touch the barrel.  Legal for CMP/DCM competition.

Vmatch - the Vmatch is functionally similar, but uses an aluminum tube that replaces the standard barrel nut and handguards.  This tube floats the barrel.  [i]It is important to remove the sling swivel that is mounted to the front sight and get a Harris #5 kit to mount the sling to the float tube, else you negate the value of the floating tube if you use a sling[/i]

So would that mean adding anything that attaches to the barrel of the free-floating barrel rifle would have an adverse effect on the accuracy?  If you add one of these [url]http://www.bushmaster.com/shopping/scopes/yhm-9370.htm[/url] with a light and flip-up front sight attached, would that "drag down" the barrel?