Firearms

The Home Built AR-15

Seekins AR-15 handguard

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)

  1. 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.

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

  3. 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.

    1. 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.

  4. 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.

  5. 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..

    1. “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?

    2. 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”

  6. 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.

  7. I recently built my first and second AR’s. AR1 is 5.56 version with a 16″ barrel and is made up of mostly Aero parts except for the barrel and BCG (Bolt Carrier Group). The barrel is an AR Stoner and BCG is a Wilson Combat (full auto version). I researched the barrel and decided to take a chance on it and I am very pleased it and it was much cheaper than most but still Mil Spec. The BCG is awesome and worth money. Everything else is Aero and very pleased with all their parts. No rattles in the rifle and everything fits tight and right. If you sign up with Aero you can get daily deals on parts which will significantly reduce the overall cost of the build. You will be ab;e to get all the parts you need for a complete Aero build on sale if you choose to do so.

    AR2 is a 10.5″ pistol build in .300 Blackout. I love this pistol ( will eventually be a SBR (Short Barrelled Rifle). I am impressed with this round, even though it is a bit pricey. You can build the rounds for it using .223 cases (check out You Tube) and save a fair amount of money reloading your own rounds. This pistol also uses an AR Stoner barrel and an AR Stoner BCG (Mil Spec). For the price, I wan’t to give a try and see how it functions. All good so far. Takes a pistol stock and buffer tube set and the over all length is 29″ and this thing is light weight. Shoots great. Both have adjustable gas blocks from Superlative and they adjust from the front, which I like. I will get a 10.5″ .223 barrel and a 16″ .300 barrel so I can set up either AR the way I want to since they both use the same 5.56 BCG and magazine, a barrel change is all it takes. Love Peggy Sue (AR1) and Betty Lou (AR2)! Good luck with yours!

  8. I’ve heard the AR requires a lot more cleaning etc. than the AK. Also, the AR is more accurate than the AK at longer ranges; 150-300 m. How is the 7.62×39 round in the AR compared to the 300? I’m leaning to the AK round. Help me out here.

    Thanks You, Hav

    1. @ HAV I have two captured 7.62×39 weapons an SKS and AK I have fabricated my own .300 BLC one rifle and one pistol I prefer the .300 over the 7.62×39 because of accuracy of both a weapon is only good if you can hit what you aim at

    2. Well , Hav , I can only speak to the AR built with 7.62×39 ( as I have one STI AR with M-4 contour barrel ).I also have a Galil and I like the ammo commonality . I buy Only brass cased ammo at this point , ( although I used to get the Wolf and WPA and such-as long as they were Non corrosive and had no enamel coating to gum up the action or cause loading problems with the 7.62×39 AR mags all made by ASC ) . I LOVE the idea of the .300 Blackout , but ammo findability to me is a concern . Maybe 10-20 yrs from now it will be FAR more common, /shrugs. I clean my weapon after every outing ( personal pref.) Sighted in 1 inch high at 100 yrds , I can hit 10 inch steel targets at 340 yards using the Scope Mil-Dot range markings out to 340 yards > 3 out of 4 shots , And 8 inch steel round targets every time at 200 or less . That’s good enough for me .

  9. It says he used the Aero upper and lower but I missed which trigger group and bolt carrier groups he used. Were they Aero as well? If not, then he missed very important aspects of the rifle.

  10. I’ve built several ARs, it can be addictive. As mentioned in prior remarks; I have a 16″, 18″ & 20″. The latter two with adjustable gas blocks, all with YHM QD mounts for suppressors. Presently, I’m assembling an A2 lower to swap out the .20″ when the mood strikes.

    I built the 20″ originally for an A2 lower, then replaced the A2 stock with a Magpul PRS. Having a spare lower, since Christmas, I decided to build another A2 lower since I had the stock, stripped lower and parts kit on hand.. So I purchased a second A2 buffer, spring & tube, and bought a two stage trigger from Stag Arms. I do not care for the stock triggers and my hands are too large for the standard AR handgrips.

    I see you’ve built an SBR, reluctant to give BATF the fee for a fourth tax stamp, while I wouldn’t mind having one, or more SBRs, I don’t feel like waiting another 9-12 months for a stamp either.

  11. Interesting article. Yes, because the AR is a modular weapon, anyone with a bit of mechanical ability can build one. I do not care for the .300 blackout round as it is “heavy’ for capability” and was originally designed for suppressed weapons. I much prefer the 6.5 because of its ballistic coefficientcy. My first build was a 6.5 Grendel that i built because I like how the Grendel shoots and wanted a ‘black gun’ to compare with my custom 6.5 Grendel bolt gun that was built with a SS Lothar-Walther barrel mounted on a Savage 16 FSS action with an accu-trigger and accur-stock. I also jhave a .30 carbine AR-15 in the works utilizing a .30 carbine barrel because no one builds a .30 barrel with 1 in 20 twist. That one needs the expertise of a machinist so my current build is a .308 LR-308. I WAS going with 6.5 Creedmore, but the ammo requires too much work: resizing brass, availability of brass, etc. Besides, in addition to my AR-15 6.5 Grendel and my 6.5 Grendel bolt gun, i already have a M96 sniper rifle with a 30 inch barrel in 6.5 x 55. With the .308, I’m utilizing a Madison poly lower with Aero upper and BCG, a free float hand guard from Monstrum Tactical and a fluted 18 inch Ballistic Advantage Chrome moly barrel with a Sop Mode 6 position stock that has tubes on both sides in case I wish to use lead cylinders to reduce recoil. I use 18 inch barrels on my builds and then put Vais muzzle brakes on them to reduce recoil and aid in accuracy. Both 6.5 Grendels have SS barrels from Lothar-Walther in Georgia>excellent barrels if you do not mind the wait. I like the 20 inch overall length as I shot National match for the US Army Reserves for several years and like the accuracy given. For both hunting and target practice, I cannot even contemplate a 16 inch barrel! One caveat that I think should be included here is that if you do not have the experience of mounting your free float hand guard and the gas tube, have a gunsmith do it on your first build and learn from him. This connection is, most likely, the most important part of the entire build and has to be torqued.

  12. Good write-up.. I’ve built 2 (one from a kit, one from scratch) and a lower for 450 BM upper. I am not mechanically inclined, but with the help of online videos and some internet research, plus buying the right tools, it took about 8 hours over two days. I recently field tested my scratch build at an NRA tactical carbine course. It passed with flying colors – after a few shake out adjustments.

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