The question of LaRue upper receiver compatibility with DPMS lower receivers is a common one among AR-15 builders and enthusiasts. The short answer is: generally, yes, but with caveats. While both LaRue and DPMS utilize the AR-15 platform, subtle variations in manufacturing tolerances can lead to compatibility issues. Let's delve into the specifics.
Understanding AR-15 Receiver Specifications
The AR-15 platform, while standardized, isn't perfectly uniform across all manufacturers. Slight variations exist in dimensions and tolerances, particularly in the receiver extension (buffer tube) area and the receiver's mating surfaces. These minor differences can sometimes prevent a flawless fit between uppers and lowers from different brands.
LaRue's Approach to Manufacturing
LaRue Tactical is known for its high-quality, precision-manufactured components. They adhere closely to AR-15 specifications, but their rigorous quality control might result in components that are slightly tighter fitting than some others. This precision is generally a positive, leading to improved accuracy and reliability.
DPMS Lower Receivers: A Note on Variations
DPMS lowers, like those from other manufacturers, can exhibit minor variations depending on the specific model and manufacturing run. While generally adhering to Mil-Spec standards, individual units can show small inconsistencies.
Potential Compatibility Problems and Solutions
While most LaRue uppers will mate with DPMS lowers without issue, potential problems include:
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Tight Fit: You might experience a slightly tighter fit than expected when assembling the upper and lower. This isn't necessarily a problem, but it might require a bit more force to securely connect the receivers. Avoid excessive force; if you encounter significant resistance, carefully examine the mating surfaces for any obstructions.
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Headspace Issues: While unlikely with a properly manufactured LaRue upper and DPMS lower, always verify headspace after assembly. Incorrect headspace is dangerous and can lead to catastrophic failure. Use a headspace gauge to ensure it falls within the safe operating parameters.
Tips for Successful Assembly
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Thorough Inspection: Before assembly, carefully inspect both the LaRue upper and DPMS lower for any visible imperfections or burrs. Remove any debris that might interfere with a proper fit.
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Lubrication: Applying a light coat of gun oil to the mating surfaces can help facilitate assembly and reduce friction.
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Gradual Pressure: When connecting the upper and lower, apply firm but gradual pressure. Avoid forcing the parts together, as this can damage the receivers or other components.
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Professional Assistance: If you encounter difficulty during assembly, seek assistance from an experienced gunsmith.
Conclusion: Proceed with Caution, but Expect Compatibility
In most cases, a LaRue upper receiver will function correctly with a DPMS lower receiver. However, always exercise caution during assembly and ensure proper headspace. A thorough inspection, careful assembly, and attention to detail will significantly increase your chances of a successful and safe build. Remember, safety should always be your top priority when working with firearms.
