What Uppers Work with DPMS Gen 1 Lowers? A Comprehensive Guide
Finding compatible uppers for your DPMS Gen 1 lower can be a bit tricky, as there are subtle differences between generations and manufacturers that impact compatibility. This guide will clarify which uppers work seamlessly and which might present issues, helping you make an informed decision for your AR-15 build.
Understanding DPMS Pattern Lowers:
DPMS (Defense Procurement Manufacturing Services) was one of the early players in the AR-15 market, establishing their own pattern of lower receivers. While often referred to as "DPMS High" or "DPMS Low," the key difference lies in the positioning of the magazine well and trigger group. Gen 1 DPMS lowers are specifically identified by their unique dimensions and tolerances in these critical areas. This is why simple "DPMS compatible" isn't always sufficient.
Uppers Compatible with DPMS Gen 1 Lowers:
The most reliable uppers for your Gen 1 DPMS lower are those specifically designated as "DPMS Gen 1 compatible." This designation ensures that the upper receiver's dimensions and tolerances match the receiver extension, preventing fitting issues. Searching online retailers with this specific term will yield the best results.
While some manufacturers might market uppers as "DPMS compatible," this doesn't guarantee Gen 1 compatibility. It’s crucial to check the manufacturer's specifications and reviews to confirm their compatibility with your specific lower.
Potential Compatibility Issues and Troubleshooting:
Even with uppers labeled "DPMS compatible," minor fitting issues can sometimes arise. These may include:
- Tight fit: The upper and lower might require significant force to mate. This isn't necessarily a deal-breaker, but excessive force can indicate a potential incompatibility. Lightly lubricating the mating surfaces can often resolve this.
- Misalignment: The upper and lower might not align perfectly, creating a gap or preventing the bolt carrier group from functioning correctly. This usually points to an incompatibility.
- Functioning issues: Even with a seemingly good fit, the weapon might malfunction. This could result from subtle dimensional differences impacting bolt carrier group operation.
If you encounter these issues, consider the following:
- Check Manufacturer Specifications: Carefully review the manufacturer's specifications for both your upper and lower receivers.
- Contact the Manufacturer: Reach out to the manufacturer of your upper or lower for technical support and clarification on compatibility.
- Seek Professional Assistance: Consult a qualified gunsmith for help with fitting and troubleshooting any compatibility issues.
Key Considerations When Choosing an Upper:
Beyond compatibility, consider these factors when selecting an upper:
- Barrel Length: Choose a barrel length that suits your intended purpose (e.g., shorter barrels for close-quarters combat, longer barrels for greater accuracy).
- Gas System: Ensure the gas system (e.g., carbine-length, mid-length) is appropriate for your barrel length.
- Handguard: Select a handguard that meets your needs in terms of length, material, and mounting options.
In Conclusion:
While "DPMS compatible" uppers might work, it's best to prioritize uppers specifically labeled as "DPMS Gen 1 compatible" to avoid potential fitting and functioning problems. Always double-check manufacturer specifications and seek professional assistance if you encounter any issues. Building an AR-15 is a precise process, and ensuring proper compatibility is vital for safety and reliability. Remember to always follow all applicable federal, state, and local laws regarding firearms.
