First of all let me introduce myself.  I've been shooting firearms since I was a kid and have been wanting to buy/build an AR since my military days.  I have been browsing this site for a while, but haven't seriously stopped until I got into my present project, which is my first AR-15.  I've been browsing all day trying to soak up as much info as I could but I still have some questions.  Please bear with the length of this post.  My goal is to build an AR as close to the military M4 with a few exceptions.  I've ordered my 6 position stock from TAPCO and I'm doing research to figure out what I want to go with for the rest.  Since this is my first build, I'm looking to save money so it IS a factor for me, however I would like to give up as little quality as possible.  Originally, I was going to go with a Bushy lower and upper but after some additional research I believe I'm going to go with RRA.  Unless I'm missing something (and please point this out to me), there isn't that much special to look for in a lower besides ensuring that it's forged, not cast which RRA's are.  This brings me to the upper and where the majority of my questions are.  For example, looking at the different uppers at ADCO firearms, www.adcofirearms.com/rockriver/rrauppers.cfm?page=rra, I'm not sure I understand the differences between what I think I'm looking for.  I want the A4 CAR I thought, but then I saw the M4 Entry variety and that's where I got confused.  Is the difference is the length of the handguards and thus the length of the entire upper?  Now on to the options.  I know that chrome lining is what I need and a float tube will possible help for accuracy.  Is this the same thing as the free float barrel?  With a "pre ban" configuration it will come with a flash hider and bayonet lug, so what is a muzzle brake?  Isn't that the post ban title of the fake FH?  Also, what the hell is a weaver gas block?  One last question before I kill all of you with boredom - is it recommended to go with a stainless bolt/carrier?  Thanks in advance for your help and patience with me, it's been a long time since I've messed with an M4.

1. RRA is a fine choice
2. I believe the A4 car is 16" w/out a muzzle device. The m4 Entry has a 14.5" plus a muzzle device to make it 16" OAL. The handguard lenghts are definitely the same.
3. Float tube/handguards are needed to free floating a barrel.
4. Muzzle brakes reduce recoil and muzzle rise. The 'prebans' come with flash suppressors, and as the name implies reduces flash.
5. A weaver gas block is used instead of the traditional iron front post. It holds the gas tube that operates the rifle and has a weaver mount on it so you can mount a variety of flipup sights.
6. Although the SS bolt carrier is easier to clean, go with the tried and true standard bolt and carrier.

Thanks!  So if I understand correctly, the muzzle brake and the Flash Hider are two different animals and for the free float barrel, I'll need to get different handguards and a float tube, or will getting the float tube take care of that?  

Yes generally speaking it is either a flash suppressor OR a brake and not both at the same time. As for the FF barrel, you can get a variety of tubes.

The standard aluminum ones



or a whole slew of FF tubes with rails on them

Quoted: My goal is to build an AR as close to the military M4 with a few exceptions.

Ok.  That should be easy enough.

I've ordered my 6 position stock from TAPCO

Will be interested to see how that works out.  Those stocks are Leapers/made in China... and the first batch of the CAR stocks were crap.  Maybe they have gotten better.  They could only go one way.

Originally, I was going to go with a Bushy lower and upper but after some additional research I believe I'm going to go with RRA.

Fine.  Nothing wrong there.  You may find some upper fit really tight on RRA lowers, but a little filing and they will go together.  I have two RRA's and they are fine lowers...  the rear shelf sits a little high in the back... so you cannot use an accuwedge if you wanted to... it used to really annoy me for some reason but I have finally been able to let it go.  You might want to check into Stag Arms lowers as well... they are made by the same company that makes RRA lowers, so the quality is going to be the same, and they are even cheaper.  I get mine from here:  Eagle Firearms

This brings me to the upper and where the majority of my questions are.  For example, looking at the different uppers at ADCO firearms, www.adcofirearms.com/rockriver/rrauppers.cfm?page=rra, I'm not sure I understand the differences between what I think I'm looking for.  I want the A4 CAR I thought, but then I saw the M4 Entry variety and that's where I got confused.

Instead of going through all the RRA options, youd be better served by calling up Rock River or ADCO, telling them what you want, and letting them help you decide.

This all depends now on how close you want to be to the real deal.  The M4 is a 1/7 twist, 14.5" barrel.  So you have two things to decide.... what twist rate do you want and how long do you want your M4 barrel.

On twist... if you demand 1/7, then that will limit your vendor options, because not all vendors make a 1/7, many make a 1/9.  In any case, both twist rates are fine for the majority of ammo you will likely shoot.

On length... I recommend getting a 16" barrel.  if you go "milspec" and get a 14.5" you have to permanently attach a flash hider to get the barrel to 16" over all length (OAL).  This will mean a slight loss in velocity of your bullets, and most importantly, if you ever want to add a free float rail... you have to remove the front sight base... which requires removal of the flash hider.... big pain.  Going 16" removes all this.

I know that chrome lining is what I need

Yep.

and a float tube will possible help for accuracy.

Yep... but most get the float tubes on a M4 for the rail capabilities as well.

Is this the same thing as the free float barrel?

Yep.

 With a "pre ban" configuration it will come with a flash hider and bayonet lug, so what is a muzzle brake?

Thats pretty self explanatory.  Screw brakes, unless you compete in 3-gun.

Isn't that the post ban title of the fake FH?

Nope.  Fake FH is a muzzle device that slips over the barrel, and looks like a FH.... but offers no other effect.  MB's actually vent gasses up and back, thereby reducing felt recoil and muzzle climb, but add lots of noise and blast to the shooter and those around him.

I think you can figure out what a weaver gas block is.... and stick with a plain jane bolt/carrier.... RRA makes a good one.

Is the Weaver gas block the way to go or should I stick with the iron front sight post? One more question I thought of: I would like to get a RRA upper that is chambered for 5.56. Are they available and where can I go to get one?

Quoted: Is the Weaver gas block the way to go or should I stick with the iron front sight post?

That depends on what you *want*.  No-one else can make that decision for you, a there is not right way on that.  Standard FSB is good because it's tough, proven, and works.  Gas block is nice because if you run optics, you can use a flip down or removable front sight, to get it out of the way.  Only reason I would ever run a weaver gas block is if I was going to make a rifle with dedicated optics (like a scoped varmint rig) or if I *really* wanted a flip down front sight.  Personally, I stick with the standard FSB.

One more question I thought of: I would like to get a RRA upper that is chambered for 5.56. Are they available and where can I go to get one?

Any number of dealers here carry RRA.  Eagle Firearms, ADCO, LegalTransfers, ad nauseum....  Almost all the RRA uppers are chambered to NATO 5.56 spec.... except the match barrels.

Thanks again!  You've been great!

When attaching the stock assembly to the lower receiver, is this the only tool I'll need?

www.bushmaster.com/shopping/gunsmith/223-telewrench2.asp

Also,  I was reading somewhere about certain carbine uppers will not fit bayonets, can anyone help me out with info on this?

I just found out about LMT uppers.  They look to be the closest to MILSPEC.  What are the pros/cons of mismatching uppers and lowers?  How can I find out if the finish is the same color between the two?