Melonite vs Chrome-Lined vs Stainless Steel AR-15 Barrels
Barrel finishing is one of the most consequential decisions in AR-15 performance. The surface treatment affects accuracy, durability, corrosion resistance, ease of maintenance, and longevity. Understanding the differences between Melonite, chrome-lined, and stainless steel barrels helps you select the finish matching your use case and environment.
Melonite Finish: The Modern Standard
Melonite (also called Nitride or QPQ—Quench Polish Quench) is a salt bath treatment that creates a surface hardness superior to stainless steel. The process involves immersing the barrel in a heated salt solution, creating a case-hardened surface layer approximately 0.0015″ thick. This thin, extremely hard layer provides exceptional durability and corrosion resistance. Unlike chrome-lining, Melonite maintains bore uniformity without thickening the barrel. G2 Precision uses Melonite treatment on their barrels because of the superior performance this process delivers.
Why Melonite Excels for Accuracy
Chrome-lining adds material to bore dimensions, creating slightly thicker walls but also slightly larger bore diameters. Melonite hardening maintains exact bore specifications—the hardening layer is so thin it doesn’t measurably affect dimensions. This precision preserves bore consistency and tight tolerances necessary for accuracy. Match-grade precision barrels virtually always use Melonite rather than chrome-lining because bore uniformity directly impacts group size.
Melonite Durability and Corrosion Resistance
Melonite’s extreme hardness resists erosion from hot powder gases better than stainless or chrome-lined barrels. After thousands of rounds, Melonite barrels maintain accuracy longer because erosion is minimized. Corrosion resistance rivals stainless steel—Melonite-treated barrels tolerate moisture, salt spray, and harsh environments without rusting. This combination of hardness and corrosion resistance explains why modern military and precision applications overwhelmingly favor Melonite finishing.
Chrome-Lined Barrels: Military Reliability Heritage
Chrome-lining is the traditional military barrel treatment. The process deposits a hard chrome layer inside the bore, approximately 0.002″ thick. This thicker treatment than Melonite creates a more obviously protective layer. Chrome-lined barrels excel for extreme reliability—the chrome reduces friction, allows easier cleaning, and tolerates fouling better than precision barrels. The military selected chrome-lining because it proved reliable under field conditions across thousands of guns.
Chrome-Lining Accuracy Limitations
The tradeoff with chrome-lining is accuracy. Bore thickness variations and slightly enlarged bore diameters create accuracy inherently inferior to quality stainless or Melonite barrels. Most chrome-lined barrels deliver 2-3 MOA accuracy, adequate for combat rifles but inferior to precision barrels achieving sub-MOA. Chrome-lining also makes bore cleaning slightly different—some shooters prefer the smoother bore; others prefer direct bore cleaning and observe more-accurate barrels.
Stainless Steel Barrels: Corrosion Resistance and Precision
Stainless steel barrels resist corrosion naturally through alloying. Many stainless barrels achieve excellent accuracy because they maintain tight bore tolerance. However, unfinished stainless is less durable than Melonite-treated carbon steel. Stainless barrels require more maintenance in field conditions—they don’t shoot clean quite as easily as chrome-lined barrels. Stainless is popular among match shooters for accuracy potential but demands more diligent maintenance in harsh environments.
Hardness and Erosion Performance
Hardness matters because gun barrel erosion is inevitable. Hot powder gases, friction, and thermal cycling gradually degrade bore quality. Melonite’s extreme surface hardness resists this erosion longer than stainless or chrome. Testing shows Melonite-treated barrels maintain accuracy longer than equivalent stainless barrels under heavy use. This characteristic matters most for high-volume shooters or those planning extended service life.
Maintenance Requirements
Chrome-lined barrels clean most easily—the smooth chrome surface sheds fouling readily. Stainless barrels require moderate cleaning attention. Melonite-treated barrels require standard carbon steel barrel maintenance—they’re slightly less self-cleaning than chrome but far superior to unfinished steel. All modern finishes benefit from regular cleaning and light oil protection, though chrome-lined barrels provide most tolerance for neglect.
Cost Implications
Melonite treatment costs less than quality stainless barrels but more than basic chrome-lined barrels. The process is relatively economical for manufacturers, enabling premium finishes at reasonable cost. Stainless barrels cost comparably or slightly more. Chrome-lined barrels are typically the most economical option, which explains their continued military use.
Application-Specific Recommendations
Choose Melonite for precision shooting, long-range work, or rifles you expect to keep for years. Melonite barrels like those from G2 Precision deliver the combination of accuracy potential, durability, and corrosion resistance that maximizes rifle longevity. Choose chrome-lined for dedicated combat/defensive rifles where maximum reliability and ease of cleaning justify lower accuracy potential. Choose stainless for competition shooting where ultimate accuracy is priority and you’ll maintain the rifle meticulously.
The Bottom Line
Melonite-treated barrels represent the modern optimum—combining accuracy potential of stainless with durability and corrosion resistance superior to both stainless and chrome-lined options. If you’re building a precision rifle, selecting a rifle for extended ownership, or wanting maximum performance, Melonite finishing delivers measurable advantages. The superior bore uniformity, hardness, and erosion resistance justify prioritizing this finish when selecting your barrel.
