A Tale of Two AR's (AR-10 and AR-15 Build Projects)

wjm308

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Here is the final product of my AR-10 and AR-15 projects, if you’d like to know more about how I got here, read on below the pictures and ensuing posts.

LR_AR-6.5_Build_060.jpg

SeekinsNX_Faxon_16_3Gun_043.jpg

A few years ago, I created a thread called “Journey to my lightweight AR-10 build” or something to that effect; unfortunately, this post was on the old Scout site and all the threads have been lost to the internet ether forever. In that thread I walked the reader through the decision-making process and why I chose certain parts over others in my pursuit to build the lightest possible, but highly accurate, long range AR-10. The journey began with 308 Win in mind, because of my love for that cartridge (ever since I pummeled bunkers with the M60 some 30 years ago), but as luck would have it, the rifle transformed into a 6.5 Creedmoor almost overnight and that has been one of my favorite cartridges since. For this build I decided immediately on another 6.5 Creedmoor, besides, I had some parts sitting around for a new large frame AR build and decided to capitalize on some of those, but instead of pursuing the lightest rig this time around I instead focused on a more traditional (heavier) build. At the same time I was getting everything together for the large frame build I was tasked (for a friend) with building a precision AR-15 capable of 3 gun competitions but also for long range accuracy while keeping the weight down, so decided it would be fun to do a two part series about the nuances of building both rifles. Even though both rifles will ultimately be sold, I thought it would be fun to walk you through the process of the builds for each one.

First, we’ll start with the AR-10 6.5 Creedmoor build, or as I like to call them AR-6.5’s. I am calling this one the Custom Aero-BA 18” 6.5 Creedmoor.

Lower and Parts
Every AR build begins with the lower, this is the serial numbered part that must be purchased through an FFL.

LR_AR-6.5_Build_001.jpg

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I chose to go with the Aero Precision M5 .308 forged lower in FDE due to its proven reliability over the years and the use of 7075-T6 aluminum helps this unit be more rigid, the FDE is personal preference but sometimes I get bored with all black rifles. The Aero uses a standard Lower Parts Kit, my preference is the JP LPK’s because they have always worked in multiple platforms for me. With large frame AR builds you will have to replace the takedown pins and bolt release catch, I opted to go with the Guntec USA AR-308 Extended Takedown Pin Set because I often find those pins hard to get out and the extended pins provide a lot more grip area to pull and for the bolt catch I chose the Phase 5 Tactical Extended Bolt Release V2 for two reasons, one, the Aero has had some issues with standard bolt releases not being able to catch the bolt sufficiently and two is I like ambidextrous releases so I can manipulate the magazine and bolt from my grip hand, the Phase 5 unit combines both features into one. I also have pretty big hands but often find the magazine release requires me to alter my grip in order to press that button, so I like the extended magazine releases, I chose the Odin Works XMR in FDE to match the FDE of the lower. One of the cool aspects of AR builds is there are so many little parts and pieces you have almost unlimited options to choose different colors, shapes and sizes to match a particular design you have in mind. Instead of using the rough triggers that come with most LPK’s I chose to use a 2-stage trigger and my favorite is made by Geiselle, for this build I chose the SSA trigger which has a 2.5 lb first stage and 2.0 lb second stage for a combined break of 4.5 lbs, these triggers are really smooth and consistent. Rounding out what’s needed with the lower is the stock, there are so many good options today it might be hard to choose from, but for precision long range I tend to prefer the full stocks vs. the collapsible stocks, for this build I chose the tried and true Magpul PRS Gen 3 Stock – FDE which requires a full A2 buffer tube, spring and full size buffer to handle the kick the 308 size cartridges give.


Upper and Parts

LR_AR-6.5_Build_031.jpg

The upper provides the foundation for the bolt and barrel and needs to be built well initially to ensure precision later on, my advice is to not skimp with build technique with the upper because so much relies on everything being put together correctly, more so than small frame AR-15’s which are relatively “easy” to build and get to shoot with tight groups. For the upper I decided to match the Aero lower and purchased the Aero Precision M5 .308 7075-T6 Forged Assembled Upper Receiver, but unfortunately Aero did not have any FDE’s available at the time, so I went with the standard black knowing I would need to Cerakote the handguard anyway. The upper I purchased already came with the dust cover and forward assist installed but needed a charging handle and BCG (Bolt Carrier Group). I prefer to have a little larger latch on my charging handles so opted for the BCM Gunfighter with Mod 3 (Large) Latch made for large frame uppers, for the BCG there are many to choose from but since this build was for a 6.5 Creedmoor there are few who make BCG’s with the smaller diameter firing pin and I chose the Rubber City Armory (RCA) Standard Mass AR-10 HP with QPQ finish, HP stands for High Pressure as many 6.5mm calibers, and smaller, with 308 based cases deliver higher pressures than standard 308 and shooters have noticed they will sometimes get premature pressure signs like blown primers. The smaller diameter firing pin and bolt face firing pin hole help to alleviate these false pressure signs (if you are reloading keep your loads in close check with recommended loading techniques). The only manufacturer’s I know of who make this design for aftermarket builds is JP and RCA. Next up is the barrel and handguard. Since I don’t intend to shoot this rifle much beyond 1000 yards I decided to go with a shorter stiffer barrel and Ballistic Advantage has been getting a good reputation so went with the Premium Series 18" 1:8 6.5 Creedmoor 416R SS Barrel from Ballistic Advantage, this is a thick (stiff) barrel and should provide the foundation for some nice tight groups. Next up was the gas block and tube, BA uses a medium length tube for this barrel and I had the option to go with a regular low profile .875 dia. gas block or an adjustable gas block (AGB), if this were intended to be shot suppressed I would go with an AGB but for this build chose a standard Cross Machine J.A.G. gas block. To finish off the upper I needed to find the right handguard and accessories. I chose the Fortis (Rainier Style) 14" 308 SWITCH Keymod Rail due to its unique design with the angled front end that allows for a bipod rail to be edged out just a bit forward and I like the quick release design and solid lock up of the SWITCH. For a while I thought I might go with a 2-tone design with a black upper and FDE lower, but decided in the end to send the upper and handguard off to my gunsmith to get Cerakoted in the same FDE as the lower. For accessories I put on a Naroh Arms Keymod Barrier Stop and a Seekins Precision KM 5-slot Rail Section for bipods.

Edit: You might be wondering why I went with the basic A2 flash hider, because I did not build these rifles for my personal use and because muzzle devices are one of the easiest to replace I decided not to invest in an expensive one but allow the buyer to choose.

As one of my favorite movie characters once chided "Let's get down to the nitty gritty..." (quote from Nacho Libre)

I’m a camera guy but not much of a video guy, so this thread is going to be picture heavy. They say a picture is worth a thousand words so this is my way of writing 50,000 words without having to write “fifty thousand words” 😉

The build pictures are pretty self explanatory especially with the callout notes but please let me know if I did anything out of order and inquire if your curious as to why I did something a particular way.
 
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wjm308

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Finishing off the lower with the buffer assembly and stock.

LR_AR-6.5_Build_025.jpg

LR_AR-6.5_Build_026.jpg

LR_AR-6.5_Build_027.jpg

LR_AR-6.5_Build_030.jpg

The finished product - lower is completely assembled.

LR_AR-6.5_Build_028.jpg

LR_AR-6.5_Build_029.jpg
 
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wjm308

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The second build is the more traditional AR-15 chambered for 223 Rem or 5.56 NATO. I am calling this one the Custom Seekins NX-Faxon 16” AR-15 223 Wylde Lightweight Build.

Lower and Parts

Every AR build begins with the lower, this is the serial numbered part that must be purchased through an FFL. Ooops, I swapped the grips between the builds because the LUTH-AR Chubby grip would not work with the ambi-safety release as it's too thick on the right side with the finger bump out.

SeekinsNX_Faxon_16_3Gun_001.jpg

While the Large Frame build did not give much consideration to weight, the 3 Gun build definitely had a focus on being light, agile and accurate – with that in mind not much expense was spared. I chose to go with the Seekins Precision NX15 Skeletonized 7075-T6 Billet Ambi Lower due to its lightweight and ambidextrous features. The Seekins lower and upper kit already come with some parts like the takedown pins and bolt catch, my preference is the JP LPK’s but since I only needed a few parts to complete the lower I chose the KNS Precision Turned Lower Parts Kit along with the ERGO lower spring replacement kit along with Strike Industries AR-15 Strike Magazine Catch, I then chose the Seekins Precision Ambidextrous Safety Selector in Red to give a contrast from the black hardware everywhere else. I also like extended magazine releases, so I chose the Odin Works XMR 3 in FDE to match the ERGO Tactical Deluxe Grip which I prefer for precision over the skinnier grips out there. For the trigger I decided to try the new Elftmann AR-15 SE 3.5lb Drop In Trigger, this trigger comes fully assembled and housed in an aluminum body but provides one of the cleanest single stage brakes I’ve felt in an AR trigger. Rounding out what’s needed with the lower is the stock, and for 3 gun precision I decided to go with the Luth-AR MBA-3 Carbine Buttstock Assembly – FDE which mounted up to a Spike's Tactical 6-Position MIL-SPEC Buffer Tube Assembly.

Upper and Parts

SeekinsNX_Faxon_16_3Gun_013.jpg

The Upper Receiver was a no brainer as I bought the Seekins kit which comes with both billet lower and matching NX15 Skeletonized 7075-T6 Billet Upper, Glenn Seekins is one of the best there is with machining AR-15 receivers and this skeletonized set is one of the best I’ve seen. The upper came assembled with the dust cover and forward assist installed but needed a charging handle and BCG (Bolt Carrier Group). I prefer to have a little larger latch on my charging handles and wanted something that would stand out with the safety so decided on the Strike Industries ARCH AR-15 Charging Handle Extended Latch - Red, for the BCG there are a bazillion to choose from but since this build was for a cream of the crop rifle I decided on one of the most innovative BCG’s out with the LANTAC Enhanced AR-15/M16 Bolt Carrier Group (eBCG). Next up is the barrel and handguard. Since the primary purpose of this rifle is mid range accuracy I decided to go with the Faxon Firearms 16" .223 Wylde Mid-Length Flame Fluted 5R Barrel, Faxon barrels have an excellent reputation and the flame fluting reduces weight and looks really cool. Next up was the gas block and tube, Faxon uses a mid-length tube for this barrel so I went with a melonited VDI tube mated to an Odin Works low profile .750 dia. gas block. To finish off the upper I needed to find the right handguard and since this was the lightweight upper/lower from Seekins then why not match it up with Seekins’ own NOXs™ M-Lok Rail System because the upper rail and handguard rail match perfectly. For accessories I put on a Magpul 5-slot Rail Section for bipods.

Edit: You might be wondering why I went with the basic A2 flash hider, because I did not build these rifles for my personal use and because muzzle devices are one of the easiest to replace I decided not to invest in an expensive one but allow the buyer to choose.

So without further adieu, let's get to the build pics

SeekinsNX_Faxon_16_3Gun_002.jpg

SeekinsNX_Faxon_16_3Gun_003.jpg

SeekinsNX_Faxon_16_3Gun_004.jpg

SeekinsNX_Faxon_16_3Gun_005.jpg

SeekinsNX_Faxon_16_3Gun_006.jpg

SeekinsNX_Faxon_16_3Gun_007.jpg
 
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wjm308

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Let me know if you see any issues with my build process, I tried to put the pics in order of assembly because there's been plenty of times where I install the safety and realize the trigger won't drop in and silly things like that. Hopefully this thread inspires some of you to go out and put together your own build. Sure, you can go out and buy an AR from one of the plethora of manufacturer's there are today, but there is a special sense of accomplishment when you build an AR on your own and take it out and shoot it!
 
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Basher

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Dang, Bill! Those came out nice, and you gave me a few ideas for my own build to boot! Well done!
 

wjm308

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Thanks Belisarius.

Thanks Bash, I thought they turned out really nice as well, glad I gave you some ideas, it's just too much fun building these things :)
 

Mwalex

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Great write up. One thing I do differently is I never install the gas tube into the gas block with the block on the barrel. I do that off-gun and have a "tool" that the gas block rest in while driving the pin into the block.
 

wjm308

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Great write up. One thing I do differently is I never install the gas tube into the gas block with the block on the barrel. I do that off-gun and have a "tool" that the gas block rest in while driving the pin into the block.
Is that a tool you created or purchased? Is this so you don't potentially move the gas block out of alignment on the barrel when you tap in the roll pin? I always look at the alignment after I tap in the roll pin to make sure this has not happened, I wish there was a "better" way to align the gas block.
 

Mwalex

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Is that a tool you created or purchased? Is this so you don't potentially move the gas block out of alignment on the barrel when you tap in the roll pin? I always look at the alignment after I tap in the roll pin to make sure this has not happened, I wish there was a "better" way to align the gas block.
Here is a link to what I use:

https://www.precisionreflex.com/Detail.aspx?PROD=186782&CAT=4215

Yep, I install off gun to try to make sure that the gas ports are still aligned. That also varies based on the type of gas block that is being used - clamp or screw.
 
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wjm308

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Here is a link to what I use:

https://www.precisionreflex.com/Detail.aspx?PROD=186782&CAT=4215

Yep, I install off gun to try to make sure that the gas ports are still aligned. That also varies based on the type of gas block that is being used - clamp or screw.
Nice, I will look into those! I can't tell you how many times I've dropped that darned roll pin and now use a bucket underneath when I'm tapping it in to start, brilliant little tool! Thanks for sharing.
 

Mwalex

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I tend to tap and thread my lowers for the safety spring/detent and the rear take down pin spring/detent. One project I want to spend time on is threading the gas block and using a screw to secure the gas tube rather than a roll pin. I think that will work but I needs to tinker with it some.
 

loveha

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Title should be modified to...
A Tale of Two AR's (AR-10 and AR-15 Build Guides)
And then stickied.
This is an excellent build guide.
Maybe an edit to popular tools like roll pin punches, hammers, reaction rods and magwell vise blocks.
 

wjm308

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I tend to tap and thread my lowers for the safety spring/detent and the rear take down pin spring/detent. One project I want to spend time on is threading the gas block and using a screw to secure the gas tube rather than a roll pin. I think that will work but I needs to tinker with it some.
A lot of manufacturers are starting to offer these features, hopefully more will continue to advance in this area.
 

wjm308

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Title should be modified to...
A Tale of Two AR's (AR-10 and AR-15 Build Guides)
And then stickied.
This is an excellent build guide.
Maybe an edit to popular tools like roll pin punches, hammers, reaction rods and magwell vise blocks.
Well that is a high compliment, thank you, just thought it might be fun to do an "image tutorial". I like your idea of adding a section for popular tools that make the build process easier/more proficient.
 

TonyTheTiger

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Those guns look pretty badass. Very nice walkthrough and pictures also.
Some unusual parts choices though, particularly with regards to the 3 gun rifle. You're missing out on some significant performance benefits.
 

wjm308

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Some unusual parts choices though, particularly with regards to the 3 gun rifle. You're missing out on some significant performance benefits.
The original purpose was for long range precision while saving some weight. But instead of 18 or 20” barrel the 16” could get the job done, but please share your thoughts.
 

TonyTheTiger

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The original purpose was for long range precision while saving some weight. But instead of 18 or 20” barrel the 16” could get the job done, but please share your thoughts.
If precision is the endgame you can disregard most of the following. But if you're building a rifle specifically for 3 gun you'll want the to minimize recoil, listed in order of effectiveness, with:
1. Aggressive muzzle brake
2. Adjustable gas block
3. Low mass bolt carrier
4. Longest gas system possible for barrel length
5. Some tuning/tinkering with buffer/spring weight

Also I would put a low power hosing load in there somewhere, but you need most of those parts to really see the benefits and tune it to work properly.

Extra cool points for ultra low mass carriers, but they come with enough problems to not be worth it for most people...
 
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wjm308

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If precision is the endgame you can disregard most of the following. But if you're building a rifle specifically for 3 gun you'll want the to minimize recoil, listed in order of effectiveness, with:
1. Aggressive muzzle brake
2. Adjustable gas block
3. Low mass bolt carrier
4. Longest gas system possible for barrel length
5. Some tuning/tinkering with buffer/spring weight

Also I would put a low power hosing load in there somewhere, but you need most of those parts to really see the benefits and tune it to work properly.

Extra cool points for ultra low mass carriers, but they come with enough problems to not be worth it for most people...
Those are great points and I see a lot of 3 gun rifles with what you mention. On the muzzle brake, I chose the A2 flash hiders more as a thread protector than anything, since these rifles were built to be resold I decided to just go with A2 and keep the cost down because a lot of shooters are very particular about brakes and if I purchased brand X brake and they really wanted brand Y well there's $100 or so down the tube. I actually meant to write something about that in my description and forgot so thank you for the reminder.

I did consider the AGB, low mass carrier, +2 gas and things like that, but those things can be so finicky to tune and get just right that I decided to go with ol' reliable ;), but excellent point that this is where 3 gun is going (or rather is already at) and my title for my rifle may be a bit misleading because that is the expectation, maybe I should call it the "all purpose" kind of like the flour you buy at the store :LOL:
 
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TonyTheTiger

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Yeah if you're selling them there is no way you'll be able to get all the cool goodies that the new owner happens to want. That makes more sense now...
 

Pilotscrappy

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Excellent write up. As someone who is about to start my first actual build, I'm sure I'll be coming back to this post several times. Thanks again for such great detail.
Should be a sticky!