{"product_id":"9x39mm-278gr-subsonic-plated-lead-ammunition-20rd-box","title":"9x39mm 278gr Subsonic Plated Lead Ammunition - 20rd Box","description":"\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003eNew production \u003cb\u003e9x39mm 278-grain subsonic ammunition\u003c\/b\u003e loaded with high-quality \u003cb\u003eStarline 9x39 brass cases\u003c\/b\u003e and \u003cb\u003eplated lead bullets\u003c\/b\u003e. This round faithfully recreates the original hard-hitting yet quiet characteristics of the specialized 9x39 cartridge. Designed for \u003cb\u003eoptimal use with suppressors\u003c\/b\u003e, this ammunition delivers excellent reliability and performance in AR-platform firearms.\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eCaliber:\u003c\/b\u003e 9x39mm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eBullet Weight:\u003c\/b\u003e 278 Grains\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eBullet Type:\u003c\/b\u003e Copper Plated Lead\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eVelocity:\u003c\/b\u003e Subsonic\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eCase:\u003c\/b\u003e New Starline Brass\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eBullet Diameter:\u003c\/b\u003e .364\" \/ 9.245mm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eRounds Per Box:\u003c\/b\u003e 20\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eStandard:\u003c\/b\u003e 9x39US\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003e9x39 Ammunition \u0026amp; Barrel Compatibility Guide\u003c\/b\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003eThere are \u003cb\u003emultiple standards for 9x39 ammunition\u003c\/b\u003e, even within brands like Wolf and Tula, which use different projectile diameters and headspace specifications. Testing has revealed inconsistent loading pressures between Wolf production lots. Tula ammunition has shown similar issues — demo ammunition with lighter loads than standard production has caused functional failures in test weapons.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eChamber Variability:\u003c\/b\u003e Chamber dimensions vary significantly between 9x39 Wolf, 9x39 Russian, 9x39 CIP, and several 9.3x39 variants. Key differences include shoulder angle and length, measured between \u003cb\u003e10° and 17°\u003c\/b\u003e across manufacturers. These discrepancies can cause excessive brass stretching and neck failures upon firing. Some tooling has been found mislabeled by manufacturers.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eProjectile Size:\u003c\/b\u003e Inconsistencies in projectile dimensions have been identified across manufacturers. Wolf and Tula ammunition shows a size range of \u003cb\u003e.358\" to .364\" (9.09mm to 9.245mm)\u003c\/b\u003e. Original 2017-era barrels were designed with a bore diameter of .354\" (9mm), a groove diameter of .364\" (9.25mm), and a rifling depth of .005\" (.125mm). This variation in projectile size significantly impacts performance — some lots cycle better than others, and gas port locations have had to be adjusted between ammunition lots to ensure proper cycling in non-suppressed AR platforms.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eDifferent and Inconsistent Loads:\u003c\/b\u003e Pressure differences due to changes in powder loads have been observed and documented across imported 9x39 ammunition.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eThe 9x39US Standard:\u003c\/b\u003e To address these compatibility issues, this ammunition is manufactured to the \u003cb\u003e9x39US standard\u003c\/b\u003e — featuring a \u003cb\u003e.364\" \/ 9.245mm bullet diameter\u003c\/b\u003e with a \u003cb\u003e278-grain weight\u003c\/b\u003e, using Starline brass and precision-manufactured barrels and projectiles designed to function seamlessly together. Custom reloading dies are also available for this standard.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eBarrel Compatibility\u003c\/b\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003eThis ammunition is compatible with \u003cb\u003eKAK barrels\u003c\/b\u003e and barrels sold by \u003cb\u003eWolf, Tactical Kinetics, Krebs Customs,\u003c\/b\u003e and \u003cb\u003ePiedmont Cartridge\u003c\/b\u003e. Some case separations have been observed during high-volume full-auto firing — over 1,000 rounds in a few hours on a hot day — which was resolved by adjusting headspace. For optimal performance, consult a qualified gunsmith and use proper 9x39US gauges to confirm correct headspace.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cspan style=\"background-color: #ffff00;\"\u003e\u003cb\u003eIf you are using a different combination of ammunition and barrels, please consult a qualified gunsmith to ensure safety.\u003c\/b\u003e\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eFrequently Asked Questions\u003c\/b\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eCan I use 9.3mm projectiles in 9x39US barrels?\u003c\/b\u003e\u003cbr\u003eNo. The correct diameter is \u003cb\u003e.364\" \/ 9.245mm\u003c\/b\u003e. Any other diameter should not be used with 9x39US-spec barrels or cases.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eCan I load these projectiles supersonic?\u003c\/b\u003e\u003cbr\u003eNo. These are \u003cb\u003ecopper-plated lead projectiles\u003c\/b\u003e and are not suited for high speeds or pressures.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eCan I use my existing Go\/No-Go gauges?\u003c\/b\u003e\u003cbr\u003eNot necessarily. Gauges labeled for 9x39 Wolf, 9x39 Russian, or 9x39 CIP may not be compatible, even if similarly labeled. Always use gauges specifically labeled \u003cb\u003e9x39US\u003c\/b\u003e with 9x39US-spec barrels to ensure proper fit and functionality.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eCan I reload 9x39?\u003c\/b\u003e\u003cbr\u003eYes, reloading is possible if you have the necessary skills and tools. Verify headspace and case length carefully. If you have an existing setup that works, use your existing cases and tools with the correct .364\" projectiles.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cb\u003eDo KAK\/Wolf dies work?\u003c\/b\u003e\u003cbr\u003eYes, as long as they match your chamber dimensions.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-size: 14pt;\"\u003e\u003cspan style=\"background-color: #ffff00;\"\u003e\u003cb\u003eIMPORTANT:\u003c\/b\u003e\u003c\/span\u003e Always consult a qualified gunsmith to confirm barrel and ammunition compatibility before firing. We are not responsible for accidents resulting from negligence or unsafe practices.\u003c\/span\u003e\u003c\/p\u003e","brand":"Centerfire Systems","offers":[{"title":"Default Title","offer_id":52669038362946,"sku":"AM1053_B","price":16.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0997\/7921\/5682\/files\/IMG_6790__44832__71235.1773326577.1280.1280.jpg?v=1774274786","url":"https:\/\/centerfiresystems.com\/products\/9x39mm-278gr-subsonic-plated-lead-ammunition-20rd-box","provider":"Centerfire Systems","version":"1.0","type":"link"}