It is no secret that the AR is the best selling civilian rifle in the US with many manufacturers jumping on the bandwagon in recent years by offering their version and introducing chamberings other than 5.56/.223. As with most good ideas, often the simplest are the best. The Smith&Wesson M&P15R offers a subtle yet distinct nuance to the AR platform by chambering it in the Russian 5.45x39 cartridge. With the ever rising cost of ammunition, the 5.45x39 is one of the most available and affordable surplus cartridges found on the market. Smith&Wesson offers a full line of AR platform rifles in their M&P line ranging from basic A2/M4 variants, varmint models, tactical rifles featuring adjustable stocks and quad rail fore-ends, and custom tuned offerings by their Performance Center. By chambering the M&P15R in the Soviet/Russian 5.45x39, S&W not only further legitimizes the round in many eyes, but also seeks to attract AK users already familiar with the 5.45x39 cartridge that may be tempted to succumb to the AR lure of ready adaptability via a huge aftermarket accessory sector, increased accuracy, ergonomics, and ease of mounting optics. Please understand that there has always been a strident and ever growing throng of shooters that feel the AK system in either 7.62x39 or 5.45x39 is superior as is. Yes, AKs chambered in 5.56/.223 have been around for sometime. This is more than justified in a foreign rifle design in the land of the 5.56/223 striving for sales.
S&W reaction to rising ammunition costs by chambering an AR in the 5.45x39 will have more widespread cause/effect than anticipated. Hornady's announcement of creating VMAX loads for the 7.62x39 and 5.45x39 is a tacit admission that the Russian rounds are here to say. Many forums and discussion boards have long touted the potency and cost effectiveness of turning to the Russian rounds for training and even primary use in a fighting rifle. 5.45x39 ammunition is available via Wolf and other manufacturers along with many different importers bringing in surplus ammunition such as Century International Arms. Corrosive and non-corrosive labels need to be scrutinized so that proper care can be given to a firearm that uses corrosive ammunition. SAR did an article on the best procedures to follow several issues ago. Corrosive ammunition should not be avoided like the plague, especially once proper methods are learned and practiced in cleaning a rifle utilizing corrosive ammunition. Cleaning methods are straightforward once understood and not the alchemy some portray.
For testing, Wolf Ammunition was used in both the 60gr and 70gr FMJ variety. Some surplus 53gr 5.45x39 ammunition was used as well. This is loaded with the original 7N6 "poison" bullet that first gained notoriety in the Soviet-Afghan War. Basically, the Russian designers constructed the 53gr. FMJ with an air cavity behind the tip of the bullet. The bullet was designed with soft targets such as human flesh in mind. This more readily allows the bullet nose to deform when penetrating a target creating more effective wound tracts and terminal ballistics. One downside to the surplus ammunition is that it does utilize corrosive primers. Something the Russians and other ex-Soviet bloc states insist on using due to concerns with cold weather ignition and long-term storage capabilities offered by corrosive primers. However, stocking up on it can not be resisted considering that it can be still found at 15cents a round or lower! Another load tested was the Dynamit Nobel FMJ HP 59gr imported by Century International, which was non-corrosive.
The 5.45x39 cartridge features a shorter tapered case (39mm) compared to the 5.56's longer (45mm) and straighter design. The 5.45x39's tapering aids in more reliable extraction and feeding, especially when considering the steel case’s metallurgical properties employed with the 5.45x39 compared to brass which predominates in the 5.56/.223 loadings. The more elongated bullet used in the 5.45 gives a similar OAL to the 5.56.