I need a little help!!

[TangoK]

Please forgive my inexperience here, but I could use a little help. I have a Colt AR15 A3 Tactical Carbine with the 16.5" heavy barrel. I would like to change it up a little bit by removing the stock front sight and handguard and adding a quad rail that extends all the way up to the A2 flash hider. My question is this, 1. Is this possible? 2. Can the front sight be removed? 3. What do I do with the gas tube since it ends far short of where I want my rails to end. Once again I apologize for my lack of knowledge but I figure I gotta start somewhere! Thanks!

[Jerry R]

First - welcome to the forum.

Yes, the front sight will come off. Pinned with tapered pins, just use a punch and drive them out. Be sure to tap the smaller side so they will come out. Take off the flash suppressor and slide the assembly off. The gas tube is pinned to the front sight, you will need to remove that pin and take off the gas tube.

Now, purchase a low profile gas block that will fit under your choice of rail. The gas tube length does not change. Your current front sight is also a gas block, the gas hole in your barrel is in a fixed location.

Using a rail that long implies that you will also have to remove the delta ring and springs. The new rail will clamp to the barrel nut.

This is just an overview of what you need to do, and I'm sure the technicians on the forum will correct and enhance the task at hand. Lot of great guys here, and they are always willing to help.

[TangoK]

Any idea what diameter gas block I need with Colts"heavy barrel"? I have found several low profile gas blocks but I am not sure if I need the .936 or .750".

[Jerry R]

Sorry, I'm not sure. I did a quick Google and came up with several sites that say their gas block fits the standard Colt heavy barrel, and then they have .750 diameter in parenthesis.

I went to Colt's site and could not find technical specifications.

Only one way to be sure. Put a micrometer on the barrel. I would suggest right in front of the front sight, then pull the handguards and do it again right behind the front sight assembly. It probably does not swell or shrink under the front sight tower. That should tell you what you need to know.

Wish I could be more help, but I just didn't find much on a quickie search.

[Zombie_Hunter]

Personally and this is just me. I would probably just cut down the front sight base (FSB) and us a fine file to smooth it down. But given your self proclaimed lack of experience I would probably have a good gun smith take on the task of cutting down or replacing your gas block and installing your free float rail. But Point is you could set up something like this

http://i29.photobucket.com/albums/c261/raa0211/DSC07177.jpg

[Cameron]

I had this done to my Colt AR15 A3 Tactical. The barrel is 0.75" under the gas block.

Like Zombie Hunter said I had a gunsmith remove the stock gas block and cut the front sight post off and re-contour it so that it would fit inside a Daniel Defense 12" Lite rail. You could also have the gunsmith install a low profile gas block that will fit inside you chosen rail.

This is the finished product, a Colt AR15 A3 Tactical this only things left that are Colt are the barrel and the upper.

http://farm5.static.flickr.com/4029/4325520550_c366a493d9.jpg


I had the same thing done to an LMT 10.5" in this case a local gunsmith cut off the front sight and contoured the gas block to fit inside a 10" DD rail

http://farm5.static.flickr.com/4020/4325521776_5314744253.jpg