I am getting ready for my first build. In searching this forum, and looking for info elsewhere, I see conflicting reports about the optimum barrel length. I will mostly be punching holes in paper, at the range. Perhaps some hunting, too. So what do you think, and why?  20" or 16"? Hbar or some other configuration? Muzzle brake or not?

Thanks for the insights!

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Flash hider...no.

Pros 16"
-Handier
-Less weight
Cons 16"
-Less velocity
-Shorter sight radius (less practical accuracy)

Pros 20"
-More velocity
-Longer sight radius (better practical accuracy)
Cons 20"
-Longer, more cumbersome?
-Heavier

Sight radius becomes a moot point if you scope mount, so keep that in mind. Barrel length has nothing to do with "intrinsic accuracy" (read: mechanical accuracy), in fact some argue that a shorter, stiffer barrel is probably more accurate--though this has been debated for years. I do know that I read an article in Guns and Ammo magazine where they took a 10" Super Blackhawk and cut 1" increments from the barrel and tested its accuracy from a ransom rest---best groups were with 2" of barrel length--so draw your own conclusions.

Build 1 lower, get 1 16" upper and 1 20" upper...decide which you like better and sell the other one to one of us real cheap.

Really...it's up to you.  Makes no difference IMHO unless you will be competing (rules might dictate your configuration).

--Otter

None of my 16" ARs are as accurate as my 20"...but the load I shoot was worked up for the 20" rifle, and I havent' really tried tweaking it for the shorter barrel.  I'm sure that with a slight adjustment, they could go sub moa; as it is, they all shoot right around an inch with that load, so it's not like they're terrible.  

As far as handling, I like the 16" better; it's a little easier moving around in tight spaces (if you have a tactical situation), and you can go with a shorter stock and not have the rifle go comletely out of balance.  

My advice is to get the 16" to start with, and get it without a brake.  You can always put a brake on later...but you'll have a lot more options in terms of what kind of handguards you can install w/out a brake.  

I've run into a lot of trouble lately because I needed to get the brake off my Armalite to put a float tube on, and I had to go with the FOBUS handguards on my M4 since I couldn't afford the SIR.  (Everything else needed to go on from the muzzle end, requiring that pesky brake to be removed.)

If you are absolutely certain you won't want to change the handguards to a RAS style--or you have the $$ to get the SIR--once you get it, then go ahead and get a brake ..I do think they make a difference on how the rifle feels when you shoot it, just make sure you DON'T get the dreaded Mini Y-comp hehehe.  

Well, that's just my .02, you might find you prefer the longer barrel...shoot as many different styles as you can, then decide.  Have fun, you'll love whatever you end up with.  

I don't think the 5.56 *needs* a brake.  And I have to agree that if you really want one you can put it on later.

On barrel length, get what you want.  Unless you have a specific desire to make a target rifle, you aren't giving up much with the shorter barrel.  I know few people who got 16 and later went to 20, but plenty who got a 20 and later wanted a 16.

What are you planning on hunting?

For competition shooting or the range 20" barrels are easier on the ears, esp. if you have a brake.