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Jason Schaller
Let’s assemble an AR-15 lower! An AR-15 lower receiver assembly might sound intimidating, but it’s easier than it looks. This guide breaks down every step to build your AR-15 lower from scratch—no guesswork, no stripped threads, and no flying springs. Whether it’s your first build or your tenth, this walkthrough helps you get it done right the first time. Let’s assemble an AR-15 lower
Step-by-step AR-15 lower receiver assembly guide
Works for AR-15 and AR-10 lowers (bolt catch differs)
Clear video timestamps for every part
Covers buffer tube, stock, trigger group, pins, and safety
Great for first-time builders or rebuilders
Bench block or vise
Armorer’s wrench
1/16” and 3/32” roll pin punches
Small hammer
Flathead screwdriver
Allen wrenches (for A2 grip)
Optional:
Video Timestamp: 0:34
Start with the bolt catch. Align the parts and gently drive the roll pin through. Use a bench block to avoid scratches.
Video Timestamp: 2:57
Line up the guard with the receiver ears. Support it fully before tapping the roll pin in place—these tabs crack easily.
Video Timestamp: 4:08
Insert the detent and spring in the receiver’s rear channel. Push in the takedown pin from the left side until it locks.
Video Timestamp: 5:35
Slide in the latch spring and locking pin. Compress the latch and push the stock onto the buffer tube until it locks.
Video Timestamp: 7:08
Thread the buffer tube in, capture the detent and spring, and tighten the castle nut. Ensure the end plate locks in.
Video Timestamp: 10:13
Slide the A2 stock over the receiver extension. Align the buffer retainer and secure with the long bolt.
Video Timestamp: 12:18
Insert the detent and spring. Push in the takedown pin while compressing the spring. A pivot pin tool helps here.
Video Timestamp: 13:45
Insert the catch and spring. Thread in the mag release button and spin the catch until it sits flush with the receiver.
Video Timestamps: 15:15 + 16:21
Place the trigger spring over the trigger. Install it and the disconnector into the receiver and pin them down.
Video Timestamp: 18:05
Drop the selector into the receiver. Insert the detent and spring into the grip. Attach and tighten the grip.
Video Timestamps: 20:03 + 20:29
Install the spring onto the hammer with the legs properly oriented. Push the hammer down and insert the pin.
Video Timestamp: 22:11
Insert the retainer spring and detent. Thread in the buffer tube just enough to hold the retainer. Install the buffer and spring.
Video Timestamp: 22:56
Ensure the trigger and safety work correctly. Hammer should release on “fire,” not on “safe,” and reset after cycling.
Confirm selector blocks trigger
Check hammer and trigger movement
Test mag release
Verify takedown pins move freely
Ensure buffer tube and stock are solid
The bolt catch always gave me the most grief when I was learning. If you scratch the finish here, it’s because you didn’t stabilize it right.
— Jason Schaller
You’ll need a small hammer, roll pin punches, needle-nose pliers, an armorer’s wrench (optional), and a bench block. A vice and lower receiver vise block help but aren’t required.
Yes, but it’s harder. You can use improvised tools like a flathead screwdriver and punch alternatives, but a proper roll pin punch set and bench block make the job safer and cleaner.
The bolt catch roll pin is often the trickiest due to its tight space and risk of scratching the lower. A starter punch or tool like the Real Avid punch set makes it easier.
Yes. The buffer tube must be installed first, as the stock locks into it. The detent and spring under the tube must also be seated correctly during install.
Most steps are the same, but the AR-10 uses a threaded bolt catch instead of a roll pin, and some internal dimensions may vary depending on the manufacturer.
Assembling an AR-15 lower might seem daunting, but it’s one of the most satisfying parts of building a rifle. Each pin, spring, and detent has its place—and once it’s all together, you’ll know your firearm inside and out. Whether you’re doing a custom build or replacing parts, this guide takes the guesswork out and gets you across the finish line with confidence.
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Original Content by The Rogue Banshee / My Rogue Solutions LLC.
Credit: Jason Schaller
Email: [email protected]
About the Author: Jason Schaller is a former FFL holder and founder of Eagle Eye Shooters Supply in Helena, MT, where he provided professional gunsmithing services and guided customers on all aspects of firearms ownership. Today, he teaches DIY gunsmithing at The Rogue Banshee and serves as a Chief Instructor at Freedom Crew University. With over a decade of hands-on professional experience with firearms and nearly 30 years in IT, Jason also holds top cybersecurity certifications including CISSP, CISA, and CRISC. When he’s not geeking out, he’s helping others build self-reliance, critical thinking, and firearms proficiency through real-world content.
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The videos, articles, and images shared by The Rogue Banshee feature gear, tools, and products for informational and entertainment purposes only. All activities follow local, state, and federal laws where they were conducted in. All activities are conducted safely under professional supervision in approved locations.
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