HK MR556 A4 | 2 Uppers Tested, Warranty Experience & Accuracy Results

This review of the HK MR556 A4 highlights its performance as a civilian-accessible variant of the HK 416. The rifle is praised for its smooth shooting, minimal gas in the face, and impressive accuracy, achieving sub-MOA at 100 yards. Key differences from the 416 include a non-chrome-lined barrel and the absence of a full-auto bolt carrier. Downsides noted are its weight, price, and the stock, though the gas system offers extensive adjustability.

This video details the baseline phase of a 10,000-round endurance test for the Heckler & Koch MR556 A4 rifle. Experts analyze the rifle's performance, focusing on accuracy with various ammunition types and conducting a bore scope examination after 3,102 rounds. The test aims to empirically evaluate the non-chrome-lined, proprietary alloy barrel's durability and performance compared to standard options.

This comprehensive review details the top three 5.56 rifles of 2026, selected by experienced reviewers Alyssa Seymour and Tanner after a year of rigorous testing. The evaluation methodology includes a 1,000-round baseline and accuracy assessments. Key insights cover the performance of models like the B&T SPC223, HK MR556 A4, and S5 Tactical SG-36, with discussions on ergonomics, reliability, and value, highlighting the diminishing returns on high-priced firearms.

This video reviews the Bear Creek Arsenal 20" stainless 350 Legend AR-15 upper. The reviewer details common feeding issues with 350 Legend in AR platforms, primarily attributing them to ammunition bullet nose shape and magazine compatibility. Testing reveals the BCA upper is capable of sub-MOA accuracy with certain ammunition, particularly 180-grain loads, while 145-grain FMJ rounds experienced feeding hiccups and less consistent accuracy.

Preston Moore provides an expert evaluation of the Centurion Arms Midweight CHF/CL Barrel, utilizing advanced tools like a borescope for internal inspection and a 30-shot group methodology for statistically significant accuracy data. The analysis includes detailed comparisons of barrel performance with various ammunition types, offering valuable insights for AR-15 builders and enthusiasts seeking high-quality components.

This video details a "moondust" (fine sand/dirt) test on the HK MR556 A4, a short-stroke gas piston AR-15. The rifle initially performed well with the port cover closed, firing 15 rounds without issue. However, after intentionally contaminating the bolt carrier group with moondust, the rifle began to short-stroke, failing to chamber new rounds. Despite a quick field cleaning, the failures persisted, leading the presenter to express surprise and disappointment.

Preston Moore, demonstrating high expertise, provides an analytical assessment of a Criterion CORE series barrel after 15,000 rounds. He details significant internal wear, including throat erosion and fire cracking, using specialized tools like borescopes and erosion gauges. Despite the degradation, the barrel still produced surprisingly acceptable groups with specific ammunition, highlighting its durability and the importance of testing worn components.

This video provides an in-depth review and accuracy test of a Ballistic Advantage AR-15 barrel. The presenter, Preston Moore, details the barrel's specifications, including its Hensley profile, 16-inch length, mid-length gas system, and 1:7 twist rate. He conducts extensive live-fire testing with four different ammunition types at 100 yards, meticulously recording group sizes, velocities, and rifle stability scores using advanced equipment. The results are compared against Ballistic Advantage's sub-MOA guarantee, offering practical insights into the barrel's real-world performance.

This video provides an in-depth accuracy test of the Sons of Liberty Gunworks 16-inch SPR barrel, featuring unique polygonal rifling and a 5/8x24 thread pitch. The instructor conducts 30-shot groups with various ammunition types, meticulously recording data on velocity, rifle stability, and group size using advanced metrics like the A-ZED score. The results demonstrate exceptional accuracy, positioning the barrel favorably against competitors.

This video provides a detailed comparison of two BCM ELW (Extreme Lightweight) barrels, examining their manufacturing consistency and on-range performance. The presenter conducts thorough bench inspections, including gauging, weighing, and borescope analysis, highlighting potential manufacturing variations. Live-fire testing involves 30-shot groups at 100 yards with various ammunition types to assess accuracy, velocity, and consistency, offering insights into the practical performance of these lightweight barrels.