S&W uses 7075 T6 Aluminum for the upper and lower receivers and 4140 steel for the 16" barrel. The receivers are produced by an outside source per S&W specifications and hand assembled at the S&W factory. S&W M&Ps have chrome lined the barrel bores, chambers, gas keys, and bolt carriers. This feature is readily appreciated by 15R owners shooting surplus 5.45x39 ammunition for maintenance reasons. Readership is too well versed to spend an inordinate amount of time describing what makes up an AR direct impingement gas-operated rifle. The 15R follows the M16A3/A4 pattern featuring a flattop Picatinny rail on the receiver with M4 front sight post and A2 birdcage flashhider. The M&P 15R weighs 6.5 pounds with the 6-position collapsible stock giving it a length of 35" extended and 32" collapsed. The barrel twist rate is 1:8. The 15R uses a standard dimension AR magazine with a specific follower with feed lips configured to handle the 5.45x39 reliably. Capacity is 30 rounds. Smith&Wesson M&P ARs are gaining a reputation as a quality rifle with many owners reporting no issues even after attending high volume of fire training courses. This is the best double check of quality—using a rifle under stress, getting both the weapon and user hot and dirty. The M&P15R does utilize a heavier hammer spring with the 15R to ensure reliable ignition of the 5.45x39 ammunition, which is mostly of the surplus variant utilizing corrosive primers that are tougher than normal US production primers. The spring is painted orange to distinguish it from the "normal" hammer springs that are employed by S&W in the other M&P rifles. Trigger pull is stiffer with this configuration, but not unmanageable measuring 7.5lbs with RCBS trigger scale.
The S&W M&P15R was tested at the range with various optics installed such as the Trijicon 5.5x ACOG and RX30 Reflex, ATN Ultra Sight holographic, along with Leupold Mk4 CQ/T and Prismatic sights. A detachable carry handle was even mounted at times during the various range visits. All served to illustrate the flexibility and easy adaptability of the AR platform. The 5.5x ACOG was utilized for 100yd accuracy testing and never considered as a full time optic option for the M&P15R due to weight and 5.5x magnification impacting field of view for CQB distances. The M&P15R displayed a higher degree of accuracy comparable to various AK74s tested to date. The Wolf 60gr and 70gr loads were in the 2.5" range at 100yds as was, surprisingly, the surplus Russian 53gr loads. The Dynamit Nobel 59gr loads was slightly better performing in the accuracy department. The Wolf 5.45x39 70gr chronographed slightly over 2,600fps on average with the Russian 53gr surplus, Wolf 60gr, and Dynamit Nobel 59gr all producing 3,000fps in the M&P15R. S&W is using correct barrel dimensions for the 5.45x39 round with .217 (+/-.001) bores and .222 (+/-) groove diameters to ensure accuracy. There have been reports of 5.45 barrels using improper 5.56 dimensions for various other 5.45x39 chambered rifles, which is larger, with the expected adverse effect on accuracy.
Range testing consisted of functionality test consisting of dumping multiple magazines at several targets in rapid fashion once sights were verified. Any fighting rifle, regardless of chambering, must be reliable to be worthy of consideration. Once the M&P15R proved reliable, it was then put through its paces on different rifle courses that were set up for a pending law enforcement competition that was to be held at the range. Magazine changes, shooting from the non-dominant shoulder and unconventional positions helped to put the M&P15R thru its paces. Strings of fire ranged from 15 rounds to 80 rounds with target distances measured in feet out to a couple of hundred yards. The S&W M&P15R handled as expected from an AR carbine combined with perfect reliability. Total rounds fired involving several range visits was over 2,200. The rifle was cleaned between range visits.
While the rifle never exhibited a problem during firing sequences, I did have an issue with the Wolf 70gr loads being difficult to manually extract from the chamber when unloading the rifle. The rifle had to be "mortared" with the buttstock pounded on the ground while extracting the round from the chamber. The upper was sent back to S&W who examined it and reported that a simple hand reaming of the chamber took care of the issue. This was verified once the rifle was returned the range. S&W's service took care of all of this in less than two weeks including the shipping to and fro.
The M&P15R is indistinguishable from other ARs chambered in 5.56/223Rem. S&W stamps 5.45x39 on the barrel and magazines. Shooters need to be cognizant of similar appearance any time shooting the M&P15R in conjunction with "normal" chambered ARs. The M&P15R is not targeted at LE/military but at civilians concerned with maximizing cost/shooting ratio with available ammunition while staying with AR platform versus AK, thus confusion over rifles mix matching magazines/ammunition in an armory or arms locker is minimized. The 5.45x39 is just as a viable a cartridge as the 5.56 and many will no doubt consider switching to it as a fighting rifle chambering. A stockpiling of cartridges is certainly possible with the 5.45x39 with thousands more rounds of 5.45x39 purchased versus 5.56 for the same money. Extra magazines are readily available in the $20-$30 range. S&W is offering M&P15R uppers separately as well, which will allow the ultimate flexibility for AR users to take advantage of the 5.45x39 cartridge without having to buy another rifle.