Tags: [[firearms]] [[mechanical design]] # Precision Rifle Aiming Rig --- ![[Pasted image 20250724094558.png|500]] ## Problem Statement A rifle barrel manufacturer required a specialized testing fixture to evaluate the accuracy and consistency of their barrels. The system needed to meet three critical criteria: 1. **Precision Aiming:** Capable of minute, repeatable adjustments for windage and elevation. 2. **Robust Stability:** Must withstand recoil and maintain zero between shots. 3. **Rapid Changeover:** Designed to allow quick swapping of test barrels without losing the base setup. ![[shared image (11).jpg|500]] ## Design Solution I developed a custom fixture centered around a heavy-duty inverted-ball head, leveraging its existing locking strength as the primary point of articulation. The design focused on isolating the aiming adjustments from the structural support to ensure precision. ![[shared image (13).jpg|500]] ### Key Mechanisms 1. **Compounded Leadscrew Aiming:** Instead of direct angular adjustment, I implemented a compounded leadscrew mechanism. This system translates linear motion (up/down, left/right) into precise angular changes for windage and elevation. The leadscrews provide a high mechanical advantage, allowing for fine-tuning while preventing back-drive from recoil forces. 2. **Receiver Interface Linkage:** Since the manufacturer exclusively used AR-15 receivers for testing, I designed a rigid linkage bar that interfaces directly with the pistol grip web. This provided a consistent and secure mounting point that aligned with the recoil vector. 3. **Compliant Universal Joint:** A critical challenge was coupling the linear motion of the adjustment mechanism to the angular rotation of the rifle without introducing bind or slop. * **Solution:** I designed a compliant joint (pictured in red) manufactured from TPU (Thermoplastic Polyurethane). * **Function:** The material durometer was carefully selected to be compliant enough to act as a universal joint (flexing to transmit force) but rigid enough to act as a damper, dissipating unwanted high-frequency vibrations or input noise (e.g., trigger pull disturbance). ### Results The final fixture delivered exceptional stability and usability, meeting all client requirements for rapid changeover and precision. **Performance:** The system facilitated consistent **sub-MOA groupings at 200 yards**, proving the effectiveness of the compliant linkage and leadscrew isolation. **Legacy:** The design's success established a foundational architecture for the company's subsequent research into advanced aiming rigs and recoil management systems. ![[shared image (15).jpg|500]] ![[erqag.jpg|500]]