This year, Heckler & Koch introduced a product long sought by American gun buyers: a pistol that replicates the look of the legendary MP5 submachine gun made by the company that invented it. The SP5 is made at HK’s Oberndorf factory in Germany and, with the exception of being semi-automatic-only and lacking a buttstock, faithfully reincarnates a venerated firearm that has come to define Germany’s Heckler & Koch perhaps like no other.
Like the MP5, the SP5 uses a receiver formed from two steel stampings welded together, but undergoes additional processes to prevent installation of the MP5’s trigger group and bolt carrier (to avoid having anyone inadvertently manufacture a machine gun, which is decidedly illegal for anyone without an SOT FFL, among other requirements). It operates using the roller-delayed blowback system which, though relatively costly to manufacture, is lighter weight and generates less perceived recoil than simple blowback-operated arms with necessarily heavy bolts.
This system relies on a mechanical delay, which keeps the breech closed long enough until the bullet leaves the barrel and gas pressure subsides to a level where the action can open without the risk of a ruptured cartridge case or high-pressure gas venting toward the shooter. The delay that causes the bolt to stay closed is created by the movement of two small rollers mounted in recesses on each side of the bolt at the 3-o’clock and 9-o’clock positions.
When the breech is closed, these rollers are forced outward from the bolt by the recoil spring, which applies pressure to the bolt carrier and in turn to a wedge-shaped device called a locking piece with angled surfaces that press the rollers about halfway outward from the bolt to make contact with corresponding recesses in the barrel extension. Contact between the rollers and the barrel extension keeps the bolt forward.
After a round is fired, the cartridge case presses against the bolt, which exerts rearward pressure against the rollers and forces them back into their recesses, causing the locking piece to move rearward by about 4 mm and allows the action to open. The delay in unlocking results from the rollers retracting inward and the consequent rearward movement of the locking piece.
This mechanism needs to be made to exacting dimensions to function correctly with a variety of ammunition, especially in select-fire guns. HK understands the finer engineering aspects of this system and, for example, places several grams of tungsten inside a cavity in the bolt carrier to give it proper weight, a feature not readily apparent because the cavity is welded over. Such details were lost on several MP5 copycats made in the 1990s and early 2000s, causing more than a few gun owners to be frustrated with their frequently poor and sometimes unsafe operation.
The SP5 does not lock the bolt rearward automatically after the last round is fired, a glaring omission for some shooters, but HK did make MP5s for the FBI with this functionality vis-a-vis a bolt catch mounted on the left side of the receiver. I’ve never seen a semi-automatic example, and was told by a former HK employee that German soldiers inserted a tracer round or two near the end of their mag load to warn them they were about to run dry.
The receiver, cocking tube and barrel are Parkerized, then electrostatically painted in satin black. The barrel’s tri-lug mount and threaded muzzle, however, are intentionally not painted to avoid problems when mounting attachments, something that at least one maker of imitation SP5s failed to do on its initial product run, causing in some cases mis-mounted suppressors and baffle strikes.
Its 8.86-inch barrel uses land-and-groove rifling and the chamber has 16 shallow grooves that enhance extraction by using the combustion gasses to break the expanded case free from the chamber walls before the claw extractor takes over. The barrel is threaded ½x28 tpi at the muzzle and comes with a thread protector.
The trigger group is HK’s most up-to-date design, using a steel trigger/hammer assembly with a roller sear for smoother trigger movement, a one-piece polymer housing and bilateral safety levers having a much-improved shape for easier manipulation than levers used in the past. The specified trigger-pull weight is 6.7 to 10.1 pounds. My trigger broke at 7.5 pounds with 3⁄8 inch of travel and no movement after the break.
The SP5 has a paddle lever just forward of the trigger guard and a right-side button, either of which will release the magazine. Two gently curving, 30-round magazines are included with each pistol. The magazines have witness holes at the rear indicating 10, 20 and 30 rounds, though the holes are not numerically marked.
There is an eyelet for HK-style sling clips on the left side behind the tri-lug mount, the left side of the mag well and on the end cap at the rear of the receiver. An elastic and nylon neck sling is included, but because it is single point, is only useful if attached to the end cap. A single locking pin retains this cap; removing it initiates a fairly simple disassembly process.
Iron sights consist of a fully protected front post and a completely adjustable rear. The rear is a circular drum with four square sighting notches of different widths arrayed around the drum’s perimeter. The drum can be rotated by hand to select the desired notch: smaller when finer sight alignment is needed in good lighting conditions or wider for rapid sight alignment or in low light. Elevation is adjusted using a tool included with the pistol that raises or lowers the drum, while windage is drift-adjustable after loosening a setscrew. The receiver has four notches to accept clamp-type mounts for attaching optics or accessory rails.
The SP5 comes with an attractive, high-quality, padded-nylon case with integrated hook-and-loop-backed straps to secure the pistol in place, and it has plenty of pockets for various accessories.
The SP5 was tested for accuracy and ammunition preference at 25 yards using a Caldwell Precision Turret Rest. The smallest/average five-shot groups of .38/.79, .60/.75 and 1.14/1.32 inches for the SIG Sauer, Black Hills and Winchester USA loads, respectively, underscore this pistol’s inherent accuracy partly resultant from its fixed barrel, good sights and 10.1-inch sight radius.
There were no malfunctions in more than 400 rounds fired. The sights needed little adjustment for most of the loads and none for the Winchester. Note: The drop-free steel magazines will not insert into the pistol if fully loaded when the bolt is closed, so download by a round if you plan to perform tactical reloads.
The MP5 has played a starring role in countless action movies, resulting in the popularization of a “Trained By Hollywood” technique to make the weapon ready by slapping the charging handle with the palm of your hand when the handle is held rearward in its retention notch. Though it looks cool, it isn’t the best technique and not likely the one the MP5 was designed for.
The better method is to use your support hand to pull the charging handle rearward knife-hand style with the thumb pointing up, then rotate your palm downward to release it. The charging handle has a curved leading edge seemingly made for this method, which is far more reliable and won’t bruise your hand like the “Tinseltown slap.”
Accessorizing the SP5
The SP5 was purposefully made using authentic features found on the MP5. However, two aftermarket accessories that expand this pistol’s function and ergonomics are an arm brace and a handguard that’s M-Lok enhanced, making it easily accessorized and increasing its utility.
Gear Head Works Tailhook Arm Brace
The Gear Head Works arm brace installs in place of the SP5’s receiver end cap. This brace combines the company’s proven Tailhook device with a Choate Machine and Tool-made side-folding arm. (Choate also makes several sturdy folding stocks for those who wish to obtain ATF approval to convert the SP5 into a short-barrel rifle.) The Tailhook itself is a curved aluminum hook that, when unlatched from its stowed position, reduces gun movement by bracing the handgun against your forearm. It also eliminates strain on your wrist by helping support a very muzzle-heavy pistol. More significantly, this arm brace allows the shooter to aim the SP5 using a natural one- or two-handed hold using the native sights.
There is no need to cant the pistol or install high-profile optical sights to aim it like nearly all of the more common rubber and elastic-strap arm braces mandate. Among its many virtues, the Gear Head Works brace is comfortable and quickly deployable, and the Tailhook can be reversed for left-handed shooters.
Midwest Industries Handguard
An anodized aluminum handguard from Midwest Industries upgrades the SP5 to accept lasers, flashlights and handstops mounted onto any of 15 full and 5 half-length M-Lok slots. This handguard also has two anti-rotation QD sling swivel sockets and comes with a short Picatinny rail. Easy to install, it offers a comfortable grasping surface and mounts solidly without any wobble. Just be careful not to mount a vertical hand grip without prior ATF approval lest you change the legal classification of your SP5 from a pistol to an “Any Other Weapon” and run afoul of the National Firearms Act.
Less-costly imitations of the SP5 have been available for some time now, causing inevitable internet debates comparing the price points and value of these genuine copies to the authentic model. What is not debatable are the performance and quality standards this authentic HK pistol has now set.