OSA AR-15 Assembly & Function Service
Building an AR-15 has never been easier—but building one that is reliable, accurate, and properly tuned takes experience.
At OSA, we don't simply install parts and hand the rifle back. Every build is assembled with the same attention to detail you'd expect from a premium factory rifle while maintaining the flexibility that makes the AR-15 platform so popular. Every component is inspected, properly fitted, and evaluated as part of the complete system—not just as individual parts.
Whether you're building a duty rifle, home defense carbine, competition gun, or your dream custom AR, our goal is simple: make it run, and make it run right.
What's Included
Every AR-15 Assembly & Function Service includes:
- Complete rifle assembly
- Professional inspection of all customer-supplied components
- Upper receiver lapping for improved barrel alignment
- Gas block alignment and installation
- Barrel nut torque and proper assembly procedures
- Buffer system inspection and alignment
- Complete lubrication and grease application where required
- Test firing for function and reliability
- Comprehensive build report with pass/fail evaluation of each major component
- Recommendations for upgrades or improvements based on your intended use
- Minor corrective work included (barrel dimpling, thread cleanup, small fitting work, etc.)
More Than Just Assembly
There are hundreds of companies manufacturing AR-15 components today.
Unfortunately, not all of them follow the same tolerances or quality standards.
While the AR platform has earned a reputation for being "adult Legos," the reality is that mixing components from different manufacturers often requires fitting, inspection, and occasionally correction to achieve optimal reliability.
Our assembly service focuses on the rifle as a complete operating system, ensuring every component works together the way it should.
Every Rifle Is Test Fired
Every rifle we assemble is test fired before it leaves our shop.
We're not interested in handing you a rifle that "should work."
We want to know that it does work.
If we discover any issues during assembly or testing, we'll contact you before performing any work outside the scope of the original service. You'll receive honest recommendations based on our experience repairing and building hundreds of rifles—not on marketing hype or brand names.
The final decision is always yours.
Comprehensive Inspection
During assembly we evaluate critical areas including:
- Overall function and reliability
- Gas system alignment
- Barrel installation
- Upper receiver alignment
- Bolt carrier group operation
- Buffer system function
- Receiver fitment
- Chamber condition
- Bore straightness
- General parts compatibility
Every rifle also receives a complete lubrication before final function testing.
Built Around Your Needs
No two rifles are built for the same purpose.
A duty rifle shouldn't be assembled the same way as a lightweight competition gun, and a suppressor host may require different recommendations than a general-purpose range rifle.
If you're still selecting components, we're happy to help before your build begins. We can provide guidance on:
- Barrel selection
- Bolt carrier groups
- Buffer systems
- Gas system configuration
- Compatible components
- Overall rifle setup
Getting these decisions right before ordering parts can save significant time, money, and frustration.
Turnaround
- Current Estimated Lead Time: Approximately 4 Weeks
- Lead time may vary depending on build complexity and requested modifications.
Compatibility
This service is currently available for:
- Direct Impingement AR-15s
- .223 Remington / 5.56 NATO
If you're unsure whether your project qualifies, please contact us before placing your order.
Our Philosophy
Anyone can assemble an AR-15.
Our goal is to build one that you can trust.
We approach every rifle as if it were our own—checking tolerances, correcting small issues before they become large ones, and ensuring the finished product functions as a complete system rather than simply a collection of parts.
If you're investing in quality components, they deserve to be assembled with the same level of care. That's exactly what the OSA AR-15 Assembly & Function Service delivers.
