I have an RRA A2 upper with a 20" HBAR. What I would like to do is use this barrel on a RRA A4 upper. Also, I would like to replace the front sight with an RRA gas block. What tools will I need to do this?

I think I've read enough of the other posts to know that for the barrel I will need a torque wrench, barrel wrench, and receiver block. Anything else?

I wont need to check the headspace, will I? I'm a little confused on that part. Will a standard 5.56 headspace gauge work with the RRA .223 Wylde chamber?

Now, what will I need in order to remove the front sight tower and install the gas block?

Thanks!

Before you take off your barrel you might want to look at the prices for a flat top upper in Equipment Exchange. They run around $450-600 and if you dont already own the tools you need to take off the barrel they are going to cost around $300-400 (my tourque wrench which I had to buy for machinist training cost $250 by itself).

But if you are hell bent on doing it yourself:

You will need those tools and you will need headspace gauges and yes they will work. You will also nees a set of drift punches (not center) and a hammer.

You should also get a copy of the Army TM on M16A2s, it has al the step by step instructions for replacing barrels.

Good luck.

Thanks for the quick responce. I already have the torque wrench, hammer, and punches. I have a manual that I picked up when I bought my lower and parts kit, but I seem to have misplaced it. I guess I'll try to look for that and see what I'm in for. Here's the list of parts and what I think that they cost. Please tell me if everything looks right:

RRA upper receiver: $115
RRA Gas block:       $45
Barrel wrench:       $15
Receiver block:      $30
Headspace gauges:    $30
-------------------------
Total:              $235

Thanks again!

Just so you know Ive only done this [b]once[/b] with help, so Im not exactly an expert. [:)]

I missed one thing though, your gonna need some Lithium Molybdenum Disulfide grease, which you can get from Bushmaster or Brownells.

The relavent section of the Army TM manual is 3-10. Biggerhammer has a online copy of it here [url]http://www.biggerhammer.net/manuals/tm9-1005-319-23.pdf[/url]

I dont know mch about replacing the gas block though. Never done it before, sorry.

The standard front sight is held in place with taper pins.  If you compare the two sides you will see they must be driven from the left to the right.  They require a good solid punch of the correct size and the sight must be supported with something solid.  Just laying it on a wood floor won't work.  I use the flat spot on a good size bench vise.  They require a good solid whack.

Get a good barrel wrench.  The $10 GI tool only has 3 pegs to engage the barrel nut and is prone to striping the teeth.  This is one of the common problems discussed here.  A good wrench has a star pattern that engages all of the teeth.

You will be surprised at how easy it is after the first one.

One thing that I'm concerned about: How do you get the front sight back on? Doesn't it have to be REALLY tight to prevent gas leakage?

When the taper pins seat, the sight base and the gas port will be in alignment. The gas port doesn't seal, there will always be a little leakage, until enough carbon builds up.