The Home Built AR-15

By Wilburn Roberts published on in Firearms

The AR-15 is America’s rifle in a very personal and individualist way—and in a manner no rifle has been since the Winchester ’73. The AR-15 may be modified, adapted, and built from scratch to suit the user. The rifle can be surprisingly affordable, or it may be as expensive and extensively modified as the user wishes. The rifle that was built as the subject of this review is in the middle of the road for expense, but at the top of my list for performance and versatility.

Home built AR-15 rifle

After some experimentation and acclimation the rifle is good to go.

The rifle was intended from the inception as a .300 Blackout. The basic criteria were a low recoil and low muzzle blast rifle suitable for recreational use, hunting, and personal defense inside of 100 yards. The rifle had to be reliable above all else. Next, came fast handling in tactical situations. Practical, rather than bench rest accuracy, was stressed in the original design parameter. As it turned out, the rifle is quite accurate well past 100 yards.

The parts were a well-chosen mix of quality components from top makers. The upper and lower receivers are from Aero, a respected maker of AR-15 parts. A .093 gas port compliments a pistol length gas tube. The barrel wears a Gamma 7.62 muzzle brake and the KeyMod floating rail is from Seekins Precision.

Seekins handguard on AR-15 rifle

The Seekins handguard is a great feature that received a lot of thought before deployment.

The primary benefit of the Seekins handguard is that the handguard does not contact the barrel and apply pressure to the barrel at all. Pressure on the handguard from the support hand or rest should not affect the barrel and the point of impact on the target. That is what free floating is all about.

The handguard is mounted with the usual barrel locking nut and eight attachment bolts. The rail mounting system allows attachment of many types of optics, lasers, and a combat light. The rail also allows better cooling during firing. Seekins has done an excellent job with the M LOK slots and vents.

The surfaces are not likely to abrade the hand. The rail slightly overlaps the receiver in a pleasing look. There is nothing choppy about this set up. When firing from a rest the flat bottom handguard allows for excellent stability.

The Caliber Option

Picatinny top rail on an AR-15

We liked the unbroken rail for mounting optics.

The .300 Blackout was chosen for many reasons. Low recoil and muzzle blast are among the criteria. The .300 Blackout has proven reliable and accurate, and no experimentation is needed to keep the rifle running properly. Heavy bullet loads—up to 220 grains—offer excellent accuracy in suppressed firearms. For my use, the standard 110- to 150-grain loads were preferable. The .300 Blackout is roughly comparable to the 7.62 x 39mm cartridge used in the AK-47 rifle but with greater accuracy. The receiver and bolt carrier are the same as the 5.56mm rifle. The rifle was used with the same PMAG magazines as the 5.56mm rifle. Function was perfect with 5.56mm magazines—a design goal of the .300 Blackout.

Once assembled and proofed, the rifle proved accurate using iron sights for initial work at 50 yards. The rifle handles well and the handguard proved a credible option in offhand fire and firing from a rest. Most of the initial work was done with Fiocchi’s clean burning, affordable and accurate loading.

The initial work up proved promising. Afterward, I mounted the TruGlo tactical riflescope with illuminated reticle for accuracy work. I fired the superbly accurate Gorilla Ammunition loads, and found the rifle would group thee shots into one-inch on demand at 50 yards. This was satisfying accuracy. However, the role of the rifle was better complimented with a red dot sight.

TruGlo red dot sight

The best set up for our needs came with the TruGlo red dot sight.

I mounted a 30mm TruGlo red dot and have enjoyed excellent results in speed shooting. Coupled with the SIG Sauer 120-grain load, this would be a great rifle for hunting wild boar at moderate range. Accurate, powerful, and with the capability for an instant second shot, this would be a good combination for field use.

I have been able to test three of Hornady’s .300 Blackout loads at this date. The 110-grain A Max load exhibits 2,350 fps velocity from my rifle and expands rapidly—stopping in about 10 inches of gelatin. This is a credible home defense loading.

Recoil was light. Muzzle blast is much less than the 3,000 fps 5.56mm cartridge. The 125-grain American Gunner, at 2175 fps, is an affordable loading that offers good performance. I found it reliable and accurate—as expected from Hornady. The Hornady Black loading uses a 208-grain A Max bullet at 1050 fps. This loading is particularly inoffensive in muzzle blast. Recoil is low.

Sig Sauer Elite Performance Ammunition .300 Blackout

SIG Sauer’s hollow point load is suitable for many types of game shooting.

At 25 yards, the loading cuts one ragged hole time and again in personal defense practice. I am leaning toward the 110-grain loading for wound potential; however, the low muzzle report of the 208-grain load is desirable for home defense. As you may note, this load mimics the energy of the .45 ACP handgun, but capable of much more accurate delivery.

The rifle is a great all-around shooter, and shows how careful integration of well made parts result in a rifle that offers real utility. I respect the budget but did not cut corners, and the rifle is put together properly. The Aero parts are credible workhorse receivers. I could have spent less on the handguard, but the handguard is in many ways the stand out feature of the rifle—and the single improvement that sets it apart from standard rifles.

TruGlo optics are a great choice for personal defense. I am still experimenting with loads for each chore, and that is a luxury. We have several outstanding loads to choose from. The project has been interesting, and the rifle is proving to be a much-used firearm.

Have you ever built an AR-15 from parts? What did you choose? What are your thoughts on the .300 Blackout cartridge? Share your answers in the comment section.

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Comments (22)

  • Mike

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    Palmetto State Armory lower. “Swat” upper. JP SS barrel in 223 Wylde with JP muzzle break, JP bolt and fore end with a Geiselle trigger. Shoots well under 1/2 moa with hand loads.

    Reply

  • John

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    It might be “America’s rifle”
    But they are making it illegal for American’s in Kalifornia today,
    In the rest of America tomorrow

    Reply

  • Flyingdaddy

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    Think I,was the only guy in the county without an AR. Bought a $50 stripped lower at a gun show…and the project began, piece by piece: Lower parts kit, then trigger, then buttstock, then stripped upper and bcg. Finally barrel, rail and scope. This beauty in 6.5 Grendel in a true half-MOA tool. 2.2 inches (5 shots) at 400 yards. Bottom line? Get a good barrel with matching bolt and a good trigger. Load good components carefully. It’s not rocket science.

    Reply

    • Timothy Allen Fontenot

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      I’m with the Grendel ( I bought everything on sale piece by piece)
      I use an aero Percision upper and lower and I went with the oden works handgard and their 18 inch barrel chambed in 6.5 Grendel it came with adjustable gas block and tube a matching BCG I found a POF 3.5 trigger and Magpul furniture
      Ammo is cheap thanks to Wolf and now I see that Academy has Hornaday 6.5 Grendel on their shelves.
      I thought about the 300 blackout heavily but when I found out it would only go about 300yards I decided not too I wanted a rifle that was more versatile so I did my research and Grendel won.

      Reply

  • George Dean

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    IMO: While a .300 is a nice rifle, with similar performance to a 7.63X30, unless you are a reloader or money is no object, I prefer the Ak. The ammunition for practice is much cheaper and the hunting rounds are up to the task for any mid size game.

    Reply

  • Shannon

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    You need to stake the castle nut.

    Reply

  • Lance Miller

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    I can’t believe he didn’t say a word about the most important parts related to accuracy – Why no mention of the barrel, its manufacture, it’s length (which looks like 16″), the gas block or how it shot subsonic.. I’d like to build a 300 but there’s been a lot of reports about the gun not cycling well when using subsonic bullets on a non-suppressor 16″ barrel..

    Reply

    • George Dean

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      “I’d like to build a 300 but there’s been a lot of reports about the gun not cycling well when using subsonic bullets on a non-suppressor 16″ barrel..”

      I imagine that is because firing subsonic rounds without the suppressor doesn’t provide a proper gas pulse to cycle the rifle reliably. But why shoot expensive subsonic ammo without a suppressor anyway?

      Reply

    • Mike

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      With proper gassing any 300 BLK will cycle subsonic without a supressor. This generally requires a pistol length gas system with the proper gas port size. For any current barrel available it should nowadays (didn’t always before) come that way. This is particularly critical on a pistol build. But if you research 300 BLK Subsonic Cycling it always comes to GAS for 1st, 2nd, 3rd.

      My recent PSA build eats everything. My friends didn’t. Turned out PSA left out the gas rings on his bolt. Gas.

      I somewhat concurr on the “why BLK” vs x39 but the whole point is it’s a tiny variation on the AR-15, designed to “just work”. For Ammo, sure x39 is cheap, so if that’s it go for it. but it’s hard to get in the lighter weights and 115-125 in BLK is devastating – even out of an 8.5″ pistol build. Add in the subs – and I concurr – get a Form 1 or Form 4 in the works – you’re at what the BLK was really designed for.

      So 30 cal suppressed, out of a pistol build otherwise unmodified AR15 including mags, and that’s The concept. Toss in darn good performance with supers and you’ve got a great all-around gun.

      Sub prices are also coming down and I think when stocking gets wider and deeper it’ll also be far more affordable. And the customary “start reloading”

      Reply

  • John

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    If you want the best all around rifle, build a Grendel. They shoot flatter, carry out further, and still buck wind well. Other than that, the 5.56 is an easy build, and offers the most custom options.

    Reply

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