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Homebrew AR
March 2010
Dan Martinez

Number 2 son Sam, was coming up on his 18th birthday. As a symbol of approaching adulthood, responsibility, and parental trust, Number 1 son Ben got a .30-06 and his own gun safe when he turned 18. The plan was the same for Sam.

However, a month or two before Sam’s birthday, Rifleshooter magazine arrived in the mail. In this issue, David Fortier had an article titled, “The AR Build”. The article basically described the universe of choices facing today’s shooter who may be interested in assembling his own AR-15.

This article was the spark that put the idea into my head of building a rifle from the ground up, rather than buying a complete rifle outright. Sure, I guess I knew that piece-part assembly of AR-15s was something that was becoming more common, but until I read the article, the urge to do so was not there. When I showed the story to Sam, he became similarly enthused.

I tried very hard not to let on that this might be a birthday possibility. Ben got a .30-06 because I so strongly believe that .30-06 is the one caliber that a rifleman ought to own. There is no caliber more versatile, especially when hand-loaded, for hunting anything and everything. I’ve espoused this opinion often enough and strongly enough to my boys, that I’m sure Sam figured that his chances of being the new owner of an aught-six were very near 100%.

But I knew that Sam was really more interested in an AR than an aught-six. So I started researching the vast and fascinating world of the AR-15.

I had not spent a lot of thought and interest in the AR-15 world for many years. Actually, the very first firearm I ever owned was an AR-15. My entry to the world of guns was due to a burglary in my attached garage while my wife and I slept peacefully in our bedroom. We awoke the next day to find our garage door open, and about $2000 worth of stuff missing. Within the week, I was the proud new owner of a Colt 9mm AR-15 carbine.

Well, now I had a gun, but you don’t get to shoot burglars every day, so what else can I do with it? I proceeded to teach myself about hunting, something else that I had never done. A 9mm carbine is enough gun to hunt beginner’s big game such as turkey and javelina. I did take it turkey hunting once when rifles were still legal in the fall hunt. The javelina hunting buddies I hooked up with though were handgun hunters, so next I picked up a Ruger Blackhawk Convertible with .357 and 9mm cylinders. Being a 9mm guy now, I did tag a piggy with the 9mm cylinder – but that’s another story.

Inevitably, I started thinking about deer, but of course my little carbine was not a deer hunting rifle. About that time, Colt brought out an AR-15 in 7.62x39. They say that the little Russian round is approximately equivalent to the .30-30, a legendary deer hunting cartridge. Soon my second AR-15 came home. Now I owned 2 ARs, but neither was chambered for the cartridge normally associated with the platform.

I eventually divested the 9mm from my collection, but I’ve owned that 7.62 since 1992. I haven’t used it much in recent years. It comes out every now and then when we have a three-gun shoot. But I always tell myself that it’s the last gun that I’ll ever get rid of. You know, if we ever reach the point where the shit hits the fan, that’s the gun I want in my hands. Ammo for it is cheap and plentiful.

So yes my history with the AR platform goes back a while, but I have to admit that I have not kept pace with recent developments. So I did a lot of web surfing and virtual shopping to learn something about what’s out there today. One of the best places to get up to speed on the web is AR15.com. It was there that I learned of a very good deal on a lower receiver – the starting point of a ground-up homebrew rifle build.

It seems that in the years that I’ve been sleeping (with regards to the AR platform), the AR has indisputably become America’s most popular rifle. Frankly, I don’t see how it would be politically possible to pass another nationwide “Assault Weapon” ban. Even during the notorious, but now thankfully expired 1994 AWB, the AR-15 was popular enough that it could only be nipped around the fringes. You couldn’t have a bayonet lug. So what? You couldn’t have a flash hider. Naked muzzles are more accurate anyway.

But today, the AR platform is available in a bewildering array of configurations and calibers. The stigma that the banners tried to place on the rifle only fueled its popularity. Today, you can get your AR chambered in .20 Ruger, .22 Long Rifle, .223/5.56 NATO, 5.7x28 FN, 6.5 Grendel, 6.8 SPC, 7.62x39, .30 Remington AR, 9mm, .40 S&W, .458 SOCOM, and .50 Beowulf. I probably missed a few more. In the larger AR-10 platform, how about .243 Win., .260 Rem., .308/7.62 NATO, and .338 Federal?

This doesn’t even touch on the various stock options, upper receiver choices, barrel length and weight options, fore-end configurations, sighting choices. Whew! And when you start from the ground up, this vast sea of choices lies fully open before you.

The real strength of the AR platform lies in it’s modularity. Literally dozens and dozens of manufacturers make all the various parts and the tools necessary to put together a finished rifle. Today, in the era of the internet, it’s become very difficult for makers to put out substandard quality parts. The word quickly flashes across the ‘net if your product is a POS, and you’d better fix it, or you go out of business. That’s not to say that you shouldn’t do your homework. If you come across something that looks like a very good deal, it just takes a few keywords punched in to Google or Bing to find out the scoop on it.

That’s what I did when I saw the posting on AR15.com about a lower receiver from a company called Aero Precision, assembled with a DPMS fire control group, plus A2 grip, for $130. Word on the net was that this was indeed a high quality receiver, made by an aerospace company whose primary business is making forged aluminum aircraft parts for Boeing. Aero Precision is located in Tacoma Washington.

This sounded like such a good deal that I ordered two! (I’m holding the second one in reserve for some future project …) The stripped lower receiver is the “firearm”. It is the only part that needs to be purchased through a Federal Firearms Licensee. All the rest of the gun is just parts!

For our first build, I really didn’t want to tackle some of the trickier assembly procedures like installing the fire control group into the lower receiver, or installing and headspacing the barrel into the upper receiver. That’s another beauty of putting together your own AR. You can either buy all the raw parts, or you can purchase some of the major parts preassembled, for not much more dough.

I had a bit of a dilemma. Sam’s birthday was on a Monday – the day after the weekend of the big gunshow at the fairgrounds. What better place to shop for AR parts than at the gunshow, where you can touch, feel, and smell a wide variety of parts! So I packed up and wrapped the receiver in a small box and presented it to him on Friday.

What Sam found in the gift wrapped box

To say he was surprised was a bit of an understatement. How could he ever guess that in this small box was a rifle! He was even more delighted when I mentioned that the gift came with a $500 allowance toward the purchase of an upper. I told him that what he ended up with was totally up to him, but I made it clear that beyond the receiver and the allowance for the upper, that the rest of the components to finish the rifle would have to come out of his own resources.

The barreled upper receiver assembly was the single most expensive component. The parts you get preassembled when buying an upper are typically:

  • The upper receiver
  • Bolt forward assist and ejection port cover
  • Barrel
  • Gas tube and front site or gas block
  • Handguard
  • Bolt and bolt carrier assembly
  • Charging handle

You normally want to buy the upper with the bolt, because when the bolt and barrel come preassembled together, they have usually been headspaced together.

$500 is just barely enough to buy the most basic but popular upper assembly. That would be an M4 clone top end. This upper has a 16” barrel with the M203 step down profile (in case you want to add a grenade launcher at some time in the future – yeah, right!). It is a flattop receiver (no carry handle), has the short, but larger oval diameter M4 hand guards. It also has a fixed front sight post.

Knowing that Sam would most likely be using some type of optical sight, I tried to steer him away from any flattop upper with a fixed sight post.

We took two rifles with us to the gun show to hopefully help fund the day’s shopping expedition. I had a spare K-31 Swiss rifle, and Sam had agreed to take his .30-30 Marlin that he really didn’t shoot much. As luck would have it, shortly after walking in to the second building, a guy walked up to me and met my price for the Swiss rifle. And as we were completing the transaction, the guy at the table that we had stopped in front of, asked to see Sam’s Marlin. He offered a fair price, and just like that, we were a whole lot lighter of weight and flush with funds. High five!

We ended up walking past every table at the gun show. About three-quarters of the way through I asked him which way was he leaning. At different times he had talked about an M4 clone, a CMP legal match rifle, and a heavy barrel varminter. The caliber was never in question though. Early on the decision had been made to go for .223.

At the end of it, we ended up going back to the first building we had walked through. A vendor there had a good selection of Rock River Arms stuff – complete rifles as well as various parts including upper assemblies. The good thing about this table was that though Sam was in the market for just an upper, he was able to heft and shoulder complete rifles installed with the uppers that he was looking at.

We spent some good time there the first time through, and we also spent a while there the second time back. Sam finally decided on an 18” heavy Varmint upper with a 1-in-8” twist. I liked his choice.

In overall length it is about the same as a 16” carbine because it lacks a flash hider, but has the extra two inches of barrel length for a touch more velocity. It’s short enough on the other hand, that the heavy Varmint contour barrel doesn’t really feel that heavy or unwieldy.

The hand guard is mid-length and free floated. The receiver is flattop and the gas block is sightless, but features a picatinny rail. So the option of adding iron sights (for my Military Rifle Shoot for example) is a possibility. It’s a very versatile choice with the potential for excellent accuracy.

It’s a good thing that he sold his Marlin, as the upper came in a tad over $600. He also picked up a couple of magazines and some ammo.

Well now we’re getting somewhere. We still needed a buttstock and a few miscellaneous pins and springs though. These we ordered from Midway. A standard A2 buttstock from Midway with buffer tube, buffer, and buffer spring was $55. Then we needed the buffer retainer pin and spring, plus the takedown pin, spring, and detent.

There are many resources for building your AR-15 on the internet. There are videos describing assembly steps. More traditionally, there are step by step illustrated instructions. But one of the most important may be exploded parts diagrams, so that you can identify those little miscellaneous pins, springs, and detents, know what they are called, and where they go. You can find resources such as these on the Midway website, the Brownell’s site, and again, on AR15.com.

So finally, about a week after placing our order with Midway, Sam had every part he needed to assemble a functional rifle. At first, I jumped in to start assembling, but quickly caught myself. “This is Sam’s build,” I had to remind myself. Sorry, I couldn’t help it. It didn’t take long at all for Sam to put everything together.

I had a leftover set of high Weaver style scope rings in my stash box of miscellanous gun parts, so Sam didn’t have to buy rings on his own. For the first scope to try, he had the Weaver K6 that he pulled off his Browning Micro Hunter when he replaced it with a 3-9 power variable.

When we first took it out to shoot, we got a horrible sinking feeling in the pits of our stomach. We loaded up the 10 round mag he picked up at the gun show with some of the “remanufactured” rounds we also picked up there. The rounds would not strip from the mag and feed. When we tried simply throwing a round in the chamber and dropping the bolt, the bolt would not fully close. But then the gun was jammed. The round was stuck in the chamber and we could not pull the charging handle back to extract the round. We ended up banging the buttstock on the tailgate of the truck while pulling back the handle which finally pulled the round out of the chamber. We tried this with two or three rounds with the same result. After all the anticipation of the build, we thought that we had ended up building a turkey.

Luckily the evening before, I had picked up another 50-pack of remanufactured ammo from a different maker at Sportsman’s Warehouse. We loaded some of those in one of the 30 round mags that he bought, and we got good function. Whew! No more problems after that. We set aside the gun show ammo and the 10 round mag and had no other malfunctions for the rest of the day.

The 6-power scope was not enough magnification to really wring the gun out to see what kind of accuracy it may be capable of. Plus, we were shooting cheapy commercial reloads, and the barrel was not broken in. It looked like we were seeing vertical stringing, something that should not happen with a free float barrel.

We ended up putting the AR away before finishing a box of fifty. We forgot to bring out the cleaning kit so that we could do a proper break-in procedure. We decided to cut the session short, and that we would come out again with the gun cleaning kit and some of the finest handloads we could assemble. The scope could be mounted a little higher for best comfort, and it will probably be at least a 12-power the next time out.

So adding it all up, we came in a bit below $900 total including the magazines, but not including scope and rings. A complete Rock River Varmint retails at about $1060, so we did end up saving a few bucks. The big plus though, is the fun and satisfaction of building it ourselves!

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