Heckler & Koch SL8-1 .223 Rem.
Heckler & Koch is marketing a variant of its G36 assault rifle as a heavy-barrel accuracy rifle for the U.S. market. What struck us as unusual was the marrying of a heavy barrel or other heavy componentry to what was originally a lightweight field rifle configuration. The SL8-1 is a grey polymer-stocked unit that sells for $1,249.
Our ammo selections included a range of bullet styles and weights. Bullets for these divergent uses can range all over the .223 weight spectrum. However, the SL8-1 doesn’t carry a “varmint” description, and HK’s literature doesn’t cite a specific use for its rifle. So we tended toward the upper end of the .223 weights to ensure we got a mixture of bullets that would likely serve in many conditions.
For the accuracy section, we shot five five-shot groups of the PMC 223B 55-grain Pointed Soft Points, Winchester USA full-metal-jacket 62-grain rounds, and 69-grain boattail hollowpoints from Federal, the Gold Medal Sierra MatchKing loading. We fired on a hot, muggy, overcast day that, thankfully, had light 6 o’clock tailwinds, which made reading the wind easy and swept away mirage.
The HK buttstock was too deep for the Protecktor bunny bag, so we used a pair of sandbags to keep the buttstock from wiggling. For the chronograph data, we used an Oehler 35P unit attached to a printer. We scoped the gun with a IOR Valdada 2.5-10X42mm riflescope carrying Weaver-style clamp-on rings.
We noticed some speed oddities. The HK gun showed lower velocity readings across the board, as much as 278 fps slower.
During NATO’s ground deployment in Kosovo, the year of 1999 marked the first time since World War II that German soldiers were in combat, and they were using the newly developed Heckler & Koch G36 5.56mm rifle. The G36 is a modular weapon system in caliber 5.56x45mm NATO. The barrel of the G36 can be exchanged by unit armorers to create a Rifle, Carbine, or a light support Variant using the same common receiver. Tested and currently fielded with special units of the German Armed Forces (including the new NATO Rapid Reaction Force), the G36 is now available to U.S. law enforcement.
The HK SL8-1 .223 was introduced into the commercial market in 1999. The SL8-1 is a child of HK’s G36 assault rifle, though they are cosmetically very different. Unlike earlier HKs, the G36 uses a gas system similar to the Armalite AR-18. The G36 makes heavy use of synthetic materials, including the receiver. The bolt assembly and barrel account for most of the metal in the G36 rifle, making it, and its civilian counterpart the SL8-1, lightweight and very corrosion resistant.
The HK SL8-1, which we’ve seen selling for a dealer price of $1,200 from SOG, (800) 944-4867, is mostly constructed of a carbon-fiber reinforced polymer. It uses a short-stroke, piston-actuated gas operating system with a rotary locking bolt. It houses a Stoner-style rotating bolt, cam piece, firing pin and firing pin retaining pin. The chrome-plated bolt is machined with six locking lugs.
The gun, chambered only for .223 Remington, employs a single-stack polymer magazine that accepts 10 rounds. The barrel rifling is a right-hand 1-in-7 twist. The barrel is hard-chrome plated and cold-forged with the chamber.
Overall, the gun measured 38.6 inches in length and was 2.4 inches thick. The barrel was 20.8 inches long, with a sight radius of 19.7 inches. It was 9.8 inches tall. The gun we tested weighed 8.6 pounds with an empty magazine.
The SL8-1 diverges from the G36 in a number of ways, of course, starting with the thumbhole stock. It’s a light gray color with a contrasting black adjustable cheekpiece and buttstock. The stock lines are very unusual, with an angular, cut-forward forend showing only 6.75 inches of barrel. The grip drops to a point 3 inches below the trigger guard, and the blocky buttstock is adjustable for LOP. An adjustment tool—HK’s rifle equivalent of a Swiss Army knife—is included.
The barrel on the SL8-1 is a heavy contour 1-in-7-twist tube, tapering from 0.84 inches at the chamber to 0.79 inches at the muzzle. The 1-in-7 twist ratio implies that heavier bullets such as Sierra’s 69-grain HPBT would shoot best in the gun, which is what we found. The barrel extension is molded into the receiver, and the barrel is secured to it with a cylindrical nut that is slotted at 90-degree angles. Also, the barrel is free-floated away from the polymer forend.
The SL8-1’s single-stack translucent plastic magazine is unique to the gun. It accepts up to 10 rounds of .223 Rem. (5.56mm NATO) ammunition. The magazine is a little hard to load until the shooter learns to push the round down and back properly. To our knowledge, no high-cap magazines are available for the SL8-1, and G36 magazines will not work. Reason: HK was forced to modify the G36’s existing magazine system for sale in the U.S. so that the SL8 couldn’t accept its forebear’s magazines. SL8s sold outside this country employ a 10-round, staggered, cropped G36 magazine.
The magazine release is a wide, flat tab located in front of the trigger guard. Pushing it forward allows the magazine to drop out, and its location allowed us to make single-handed magazine changes. When the last shot in a magazine is fired or when the SL8’s cocking handle is pulled back with an empty magazine in place, the follower engages a bolt catch integral with the fire-control housing. Without a magazine in the gun, the shooter can also hold the action open by retracting the cocking handle and pressing a button in front and above the trigger. The bolt can then be released by lightly pulling back the cocking handle and allowing it to push forward. In our view, getting to the ambidextrous cocking handle was blocked in part by the low sight rail.
The standard sight rail extends across the topmost length of the gun, and the polymer rail will accept virtually any type of optics. However, it’s contradictory, we think, that the gun ships with the standard open sights. The fixed front blade is too coarse for precision use, in our view, but it is shielded. The rear sight, an unshielded L-type, allows the shooter to flip between 100 and 300 meter aperatures. To make adjustments, the owner must turn 2mm allen-head screws (wrench provided), but to our eyes, the process isn’t easy. Still, the sight rail readily accepts optics like the scope we used, and there were enough crosscut slots to get acceptable eye relief.
Shooting the gun, we found the unconventionally designed stock to be both easy and not easy to handle. The forend is squarish, but the corners are beleved off. This allows the gun to sit comfortably in the hand, especially in the area just in front of the magazine well, or on the bench without rolling. To attach a sling, the shooter can fasten a swivel or hook into a hole in the molded stock.
Unlike the two ARs tested elsewhere, the HK’s rear stock is adjustable. The buttplate slides in and out of the hollow stock. Two allen head screws lock the stock down. There is 1.6 inches of length adjustment, which is made with the tool set’s 5mm allen wrench. (HK sells extra stock spacers for $6.) A hard-rubber buttpad and a polymer sling attachment are molded into this sliding assembly. The cheekpiece, mounted to two flush-fitting, threaded steel inserts, allowed us to get exactly the cheek pressure we wanted. The cheekpiece and one spacer are supplied with the rifle. Extra spacers are available.
Though we liked the variability of the butt and cheek portions of the stock, the thumbhole offers a weird handfit. Built to accommodate lefties and righties, the big hole in the stock is cut so far forward that even people with short fingers tended to overrun the trigger, forcing the first joint rather than the finger pad to make the gun fire. Also, the front portion of the thumbhole needed to be relieved and thinned on the opposite side of the stock, we think. We weren’t able to find a completely comfortable way to hold the trigger-finger hand on the gun; but we recognize there’s a variety of hand sizes and builds which would contradict our experience. The ambidextrous cocking lever was a nice addition so that right- and left-handed shooters could operate the gun.
Some observers have complained about the SL8-1 being very front heavy—and it would seem this point could be easily resolved yea or nay. We found the balance point to be right in front of the mag well, and shooting the gun standing, with the elbow on the rib cage, was very comfortable. However, because of the thumbhole grip, we liked to cant the gun heavily toward the face. In kneeling and prone, the forend fit the front hand well.
We found the trigger was better than we expected, though it didn’t have the qualities we normally like. We prefer two-stage triggers on most rifles, where between half and three-quarters of the total trigger take-up weight is pulled up in a clean, smooth stage. That leaves a minimal amount of force needed to break the trigger in the second stage. The SL8’s trigger broke at 5 pounds, which isn’t as bad as many rifles we’ve seen. But the front end of the pull was soft, leading to an indistinct “area” of break, rather than a point of break. However, we found that pulling up the slack, then firmly pulling through the release point, gave us good control.
As we’ve noted, the gun ships with tools, including 2mm, 2.5mm, 3mm, 4mm, 5mm, and 8mm hex wrenches as well as phillips and flathead scewdrivers. The 2mm hex wrench adjusts the fixed sights. The 2.5mm hex wrench adjusts carry handle optics. The 5mm hex wrench adjusts or removes the stock. The phillips head screwdriver removes the sights, sight rail or carry handle. We appreciate them providing it as a package rather than charging extra for it.
After finishing our range work, we broke the gun down to see about cleaning it. We saw that the bolt and chamber area of the rifle showed little signs of fouling. In our view, the gas system does not allow many contaminants into the action, eliminating much of the fouling common to the M16/AR-15 clones.
Accessories include the SL8-1 Buttstock Spacer, $6; SL8-1 Cheek Piece Spacer, $7; G36C/SL8-1 Picatinny Rail Short, Polymer, $30; G36/SL8-1 Front & Rear Tritium Sight Set (green front dot with two-dot green rear sight), $170; Eye Bolt, Sling/Bipod, for G36 Forearm or Knight’s RAS System, $20; and many others.