I had pretty much settled on a 14.5" barrel, with a pinned & welded comp to make it 16".  And I had pretty much settled on a free-floating forearm.  So I was playing around on Brownells, using their AR builder, trying this-and-that.  Then I watched a video tutorial on how to install a 1-piece free-floating forearm.  You have to remove the brake, front sight, gas block, gas tube and barrel nut.  Now, if the brake is pinned and welded, that means such dis-assembly is no longer possible, right?  So, once I get the barrel assembled, there's no going back, making changes, or even making repair to those parts without paying a gunsmith to cut the brake free.  Right?

So now I'm thinking that a more intelligent route is to get a 16" barrel.  I believe that it is legal to put a comp/brake/flash hider on that with red Loktite.  It will be a bit of a hassle to get it off if I ever decide to or need to, but I can at least do it by myself.  And, really, will I ever notice that extra 1.5"? 

The only reason I was thinking of a comp was to make the barrel legal, so I could go 16" with nothing attached and have the same overall length.  I've been an outspoken mocker of people who put brakes or comps on small-caliber guns, maybe I should put my build where my mouth is? 

Yes on a pin and weld there is NO mistakes, not easy to remove after. Normally we cut the brake in half to get it off.

NO RED LOCTITE!

use a crush washer or timing washers.

Some people like the shorter barrel look with a 14.7" or less barrel......then add flash hider/comp for legal 16"

I had pretty much settled on a 14.5" barrel, with a pinned & welded comp to make it 16".  And I had pretty much settled on a free-floating forearm.  So I was playing around on Brownells, using their AR builder, trying this-and-that.  Then I watched a video tutorial on how to install a 1-piece free-floating forearm.  You have to remove the brake, front sight, gas block, gas tube and barrel nut.  Now, if the brake is pinned and welded, that means such dis-assembly is no longer possible, right?  So, once I get the barrel assembled, there's no going back, making changes, or even making repair to those parts without paying a gunsmith to cut the brake free.  Right?

So now I'm thinking that a more intelligent route is to get a 16" barrel.  I believe that it is legal to put a comp/brake/flash hider on that with red Loktite.  It will be a bit of a hassle to get it off if I ever decide to or need to, but I can at least do it by myself.  And, really, will I ever notice that extra 1.5"? 

The only reason I was thinking of a comp was to make the barrel legal, so I could go 16" with nothing attached and have the same overall length.  I've been an outspoken mocker of people who put brakes or comps on small-caliber guns, maybe I should put my build where my mouth is?

My personal opinion of a project gun is make it as easy to play with as you can.  Installing anything permanently just interferes with your enjoyment.

I bought a complete 16" barreled upper and a stripped lower from Palmetto State Armory.  I picked the blemished (read: discounted) upper and lower so I wouldn't beat myself up if I did something to damage the finish!  For the life of me, I have yet to find any blemishes at all.

The upper came with a standard A2 front sight post with a carbine length gas system, It also had the beautiful [sarc] carbine length black A2 hand guard!  The muzzle device is the normal A2 birdcage flash hider that just twists on/off.  I'm waiting on a new AAC Blackout Flash Hider to replace the Birdcage.

There  was no Loktite on the flash hider when I took it off, so I didn't apply any when reinstalled.  The crush washer is curved (not flat) and applies plenty of pressure, like a steel spring.

I removed the A2 front sight and the A2 hand guard.  I installed a Troy low profile gas block and the Troy/Alpha VTAC 13" free floated hand guard and rail.

http://www.amazon.com/exec/obidos/ASIN/B009B5AP2S/?tag=2ahawaii-20

The Troy Alpha mounts to the existing barrel nut.  No special wrench needed like with some other rails.  I like the fact it has an end-to-end top rail and 4 rail "pieces" you install anywhere you want to attach something to the hand guard.  The round design and light aluminum construction give the gun a nice feel.  The 13" length puts the front sight further forward which seems to help my aim.  That length hides the gas block plus a couple of extra inches of barrel.  Troy makes a 9" and 11" length among other sizes.  Make sure whatever you get is going to at least cover the gas block.  I'm very happy I went with this one.

I have an aluminum vise block for the upper and plastic vise block for the lower.  Keeps the half you're working on immobile and protected from accidental damage:

http://www.amazon.com/exec/obidos/ASIN/B0061PWBLY/?tag=2ahawaii-20

You still need a barrel nut wrench, but those are sold everywhere and easy to borrow if need be.

You need some good punches for the gas block pins.  Be sure to only push these pins in the right direction.  One side has smaller holes than the other, so you can only extract them through the larger ones.

Free floating the barrel and adding a Troy Folding Front Battle Sight to match the rear Troy sight made a big difference zeroing the rifle.  With the A2 front sight before, I had to adjust the rear sight about 4-5 marks to the left of mechanical zero.  After the upgrades, it was perfect on the center mark.  Adjusted the front sight for elevation, but the rear sight is right on.

This is my first project AR-15.  I figured buying a complete upper would eliminate head spacing and other important concerns.  By disassembling and changing components, I'm more confident I can buy individual parts and assemble the upper with no problem.  I'm already buying parts as I find them on sale!

The lower is a piece of cake.  I used a quality Lower Parts Kit and added a couple of upgraded parts (MAGPUL MIAD pistol grip, B.A.D.D. lever and BADASS ambi safety selector).  I bought the buffer tube/stock assembly separately from the parts kit, but you can find them together on many sites.

Have fun!  I learned almost everything I needed from YouTube, forums, and , of course, having owned an AR-15 that was factory built!

As SpeedTek mentions going with a 14.5 pinned and welded is not for someone who is still "working out" what their preferences might be.  Too many go this route and then want to change the muzzle device, forend, gas block set up and now it takes some effort to remove the device, which the majority of the time means that the device is ruined, by either splitting it or milling it off.  There are some set ups where you can slip the rail forward and remove the barrel from the receiver.  Realistically you only add about an extra 1.5 inches with a 16" barrel.  It is very nominal length increase and you still maintain the ease of modularity.  As for the red locktite, there is none needed anywhere on this platform.  Blue will be optimal where needed.  As for compensators, etc...Well lets just say that caliber be darned, the reality is that 99% of recreational shooters are not skilled enough, or do not have the ability due to restrictions, or the desire to run the weapon to its ragged edge of performance where the shooter will see the benefit of a device.  If I am shooting one round per second from a bench, the need is not there.  If I am attempting to get fast hits in a small target area's with say multiple targets, multiple hit zones, perhaps as distances increase, well then a very skilled shooter will see a good advantage with a device.

I do A LOT of rifles from mild to wild.  Any questions and feel free to ask.  I might also suggest m4carbine.net for a lot of good reading information.  Some of the most knowledgeable on this weapon system as a whole, but they can be a tough nut to crack for those with certain personalities.  I have the same username at m4carbine.net and can be found posting there from time to time also.  ar15.com also has a lot of good information but you have to sift through a ton of crap and waaay more idiots than people who know their stuff.  There are other sites that specialize on this platform but the traffic can be much slower.   

Yeah, go with 16" barrel so that you'll have the option to change things around.  1.5" extra length shouldn't make that much of a difference, just put on a longer free float handguard (12") to get the shorter look....unless weight is so important to you.

You may want to consider what your upper receiver group (URG) will be when completed.

The barrel and rail is a good start, but what about the type of gas system as a whole.

All the main parts have some variations or another, but not all will work together.

You may want to start with a complete picture and then break down the individual components.

If you do it the other way around, there is a good chance that you may miss something, or make a boo-boo.

Ask me, I know.

Thanks, guys!  Glad to know I dodged a misstep there!

And nice news that the crush washer is all I need!  That makes life simpler in the event of changes.

Lordy, there's a TON of info out there, and most of it is bad.  Glad I've got this place to bounce my quetsions around! 

I'm enjoying these threads.  Thank you!

I found this thread helpful too.

Officer.com: So you want to Build an AR-15, huh?
http://forums.officer.com/t81462/

I'm enjoying these threads.  Thank you!

I found this thread helpful too.

Officer.com: So you want to Build an AR-15, huh?
http://forums.officer.com/t81462/

A lot of info in that thread, however much of it is dated so keep that in mind.  I contributed quite a bit to that thread over a couple three years or so but haven't kept up with it in quite some time. 

https://www.primaryarms.com/Daniel-Defense-14-5-inch-5-56mm-LW-Carbine-CH-p/dd-10192.htm

In stock. They also have 16"