Fairly new from HERA Arms — imported and sold in the U.S. by LAN World — is the SFU, or Side Folding Unit. This stock adapter allows for folding the buttstock to the side and fits any rifle that accepts an AR-15 receiver extension (buffer tube). However, it probably won’t work on your AR-15. . .
The SFU is one sleek, slim, lightweight folding adapter. There are certainly a lot of clunky ones on the market, and this ain’t one of ’em. It looks like this on the top:
…this on the bottom, with a good view of how thick that steel hinge pin is:
…and this on the push-button release side:
As you can see, the SFU is the same diameter as a castle nut, providing a sleek, in-line appearance.
I’ve actually installed mine upside down so the stock folds to the right side, but it’s really designed specifically for folding to the left. When installed correctly, a castle nut isn’t even needed. A set screw inserts in the threaded hole on bottom, indexing with the 6:00 slot in the buffer tube’s receiver threads and ensuring that your stock is perfectly timed vertically with the SFU.
However, obviously it works in alternate orientations and, really, you could lock it to your receiver so it folds in any direction desired. Installation consists of screwing the SFU’s male side into the receiver until the unit is aligned properly…
…then tightening down the two hex bolts, which clamp the SFU’s body solidly to the receiver.
Pretty ingenious, really. It’s as simple as it is solid, while allowing infinite adjustment.
At this point, it’s probably obvious why the SFU won’t work on most AR-15s; it caps off the receiver and blocks the buffer tube. So, HERA’s Side Folding Unit is relegated to rifles and shotguns that accept an AR buffer tube — either from the factory or via an adapter — but lack your standard AR recoil system (bolt carrier passing out the back of the receiver and into the buffer tube). The CZ Scorpion Evo (SBR) here is a perfect example, and there are plenty of AR buttstock adapters for AK-47s, shotguns, and other firearms in addition to AR uppers that don’t require a receiver extension. Still, it’s a niche product for sure.
Lockup is achieved through a claw that’s depressed by the release button.
It very smoothly and easily snaps over a stainless steel pin on the receiver side, holding it firmly in place with no wiggle. Although the pin is solid and both it and the claw are steel, I’m guessing one of these things would be the weak point under extreme stress. Of course, I suppose this would be preferable to a cracked receiver.
Despite the ease with which it clicks into place and releases, the lockup is rock solid. When folded, there’s very little wiggle in the hinge either, but it glides with ball bearing smoothness.
Speaking of ball bearings, there are a couple of those inside the hinge area that act as detents when the stock is folded, although they’re pretty gentle in that role. They aren’t likely to keep most AR stocks folded if held side-down, but they’ll keep it in place while shooting with the stock folded.
On a rifle that doesn’t shoot reciprocating parts into the buffer tube, HERA Arms’ Side Folding Unit is lighter, sleeker, and less expensive than most alternatives and it’s a solid, well-made piece. Fit, finish, and function are aces. I dig it.
Specifications: HERA Arms SFU
Ratings (out of five stars):
Fit & Finish * * * * *
Machining, fit, and finish are basically flawless. I thought the install was pretty straightforward despite the German-language instructions, but LAN World put together a pretty good YouTube tutorial anyway.
Function * * * * *
My Scorp may be caught in 922(r) limbo, but I’ve been using this SFU for a few months in my dreams and it works great.
Overall * * * * *
I realize I’ve already described the SFU as a good deal, which it is compared to some of the larger, clunkier competition, but $115 still seems a tad steep. Then again, for whatever it’s worth it’s made in Germany rather than somewhere in SE Asia. You can’t beat it for sleek form factor and smooth but solid action.