Saturday, January 28, 2012

Bushmaster AR-15 (re)Build

I'm baaaack. I got really lazy with the blog updates. Lazy for two years. That's really, really lazy.
I've been busy, though. Lots of stuff going on. I've been doing a lot of shooting, and my wife has been doing a LOT of running. She even ran a half marathon at the end of last year! She's pretty awesome, really.

Well, I focused on the pistol for the past year. I've sold and purchased many pistols over the past year. I did something I never thought I would do - I bought a Glock. Yep. A G17. I quickly fell in love with it. I stippled the grip on my own, changed the sights, and changed the connector. Then I bought (and sold) three or four different Glocks. I finally settled on a Glock 35. That purchase was quickly followed by the purchase of a Glock 34.

Sadly, I moved on from the Glock line to the Para Ordnance. I still have the Glocks in the safe, but my weapon of choice is easily the Para Ordnance P16.40. I absolutely love it. The last IDPA match I shot in November was the best I've shot to date. I placed first in the match, with top honors in accuracy as well. You can view the scores at should you choose. And you really should consider shooting an IDPA match. Don't be nervous. Just go do it!

Now - on to the AR-15 build.
A week ago, Kelly ran a 5k in Austin. It was called the Austin Gorilla Run. A little over 1100 people gathered in Austin dressed in gorilla costumes and ran through Austin. Check out Kelly's blog post at

While we were in Austin, I met with a high school buddy of mine for dinner at The Salt Lick. Sunday morning, we all met in Bulverde at Cedar Ridge Range for a carbine match. A carbine match is similar to an IDPA match except one shoots a rifle instead of a pistol. We also carried a sidearm in this match, and at times we transitioned to the pistol. It was one fun time.

I learned a lot shooting that match. Among the things I learned was that I needed to do a few things to my AR before I could be competitive shooting a 3 gun match. I thought for the longest time that I wouldn't need to worry about a flash suppressor or a compensator for the AR. I also had an EOTech 512 HWS mounted on my AR. All of these things I thought I wanted, but it turns out that I was wrong. So, I sold a couple of things in order to quickly raise money to change up my AR15.

Fortunately for me (unfortunate for Kelly), there is a shop in Pearland called Primary Arms. You can visit their website at GREAT group of guys there.

Here is what my carbine looked like this before I started (note the lack of flash suppressor/compensator):

After spending two hours at Primary Arms, I was anxious to get started. I spread an old sheet over the dining room table and got ready. I did the normal; checked to make sure the rifle was unloaded, and started taking things apart. I removed the handguards first.

Then it was time to remove the front post sight. This was frustrating at best. I am not sure what Bushmaster does when they install these, but I worked on removing it for at least an hour. I got out the Dremel tool and tried grinding the pins down. I was able to remove the sling mount, but gave up removing the pins holding the sight to the barrel. I removed quite a bit from the front sight before giving up.

So, the only way for me to remove the barrel and use the same upper receiver was to cut the gas tube in the middle and remove one half from the reciever side. Easy enough. I called Primary Arms to make sure they had one in stock, and Mr. Loomis placed one aside for me. When I arrived to pick it up, we pulled an assembly diagram to make sure I didn't need any additional extraneous parts.

Gas tube and barrel removed, I could now start assembly. I purchased a Yankee Hill Machine barrel with a 1:7 twist. Barrel twist selection is one of those topics that is discussed ad naseum on many forums and everyone has their favorite. I chose 1:7 so that I would be able to shoot a variety of available bullet weights reliably.

Barrel installation was a snap. I used a cheesy 3" clamp on bench vise (I will be purchasing a much larger bench vise for future AR builds). Among my purchased items was an 11" Troy free float hand guard. It was supplied with a replacement barrel nut and the tool with which to install said barrel nut.

Next was the gas block installation. The gas block sits over a small hole in the barrel and routes gas from the burning powder back to operate the bolt. In order to keep the gas block where it needed to be, I used a liberal amount of loctite red on the barrel and on the hex keys. I also drilled small recesses into the barrel so the hex keys would have something to keep them put.

With gas block in place, there was little left to do. I slipped on the Troy free float hand guard. I chose this one (the TRX Extreme battle rail) because it is a bit thinner than most. It's also not covered in rails. I like to attach gadgets to my rifle as much as the next guy, but in reality I am not going to use 44" of rail. The troy came with additional rail pieces that will allow me to attach a few things such as lights or lasers, and placed the two shorter ones on either side of the rail close to the muzzle. There I can hang a light on one side, and a swivel sling attachment on the other.

Also purchased were Troy flip up BUIS (back up iron sights). I chose the HK style front sight, and the Di-Optic rear. The Di-Optic rear because it's different. It's not the standard circular aperture. This one is diamond shaped and has markings at the corners. I feel it help line up the front post more quickly. For longer range, a variation of pistol sight is used for the rear. It looks like this:

With the sights installed, I moved the C-More sight a little farther forward than it sat previously. I had an EOTech 512 for the longest time because that is what everyone else used. After shooting a match with it, I found it difficult to concentrate on the holographic image. My eyes wanted to focus on the scope itself. The C-More is smaller in size than the EOTech and the dot is brighter. It's also easier to activate and increase the brightness of the dot. Of course, these are just my opinions. Your mileage may vary. I also installed a polymer Magpul MOE trigger guard. This guard is just a little larger than the standard "straight" trigger guard. And I installed a Troy Medieval comensator on the business end of the barrel. The hardest part of this entire build was crushing the provided washer that came with the compensator.

The finished product:
It was a fun build. I learned quite a bit in the process, namely that it's not difficult to do this. However, should you not feel comfortable with something like this, there is probably a qualified gunsmith in your area. Just look them up and they will be happy to assist in your build. They will even help you decide on various configurations and so forth.
Next up will be the range report from this build.