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. . .
https://www.youtube.com/watch?v=Bp-CmwWzvqk
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.
Conclusions
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
Price: $115.00
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.
Would be a pretty cool option to slap on a MDT LSS chassis
For sure. It actually seems kinda rare to find a chassis system that accepts an AR stock and doesn’t already have side folding built into it (?), but chassis rifles are definitely a solid target for the SFU…
Here’s what I don’t get: Everybody that makes a side-folding stock, makes it so that the stock folds to the right and covers the ejection port, making the rifle unusable until the stock is folded back out.
On an AR, it doesn’t matter as much because, unless you’re using a bufferless setup, you can’t use the rifle until it’s folded out, anyway. But on AKs, shotguns, and just about every other semiauto rifle that isn’t a traditional AR design, it doesn’t make sense.
I installed it upside down on purpose (which is mentioned in the review). I wanted it to fold to the right, but the SFU is specifically designed to fold to the left. However, it can be installed to fold in any direction you want, as it’s infinitely adjustable 360* around.
FYI — many fold right but don’t block the ejection port because the stock is designed to leave that area open. The U.S. generally seems to prefer stocks that fold to the right. For me, I installed it this way because if I’m carrying the gun on a sling I want the flat side against my body rather than the folded stock against my body. But I may swap it up so it can be fired folded w/out the stock blocking some of the ejection port.
Right on!
ARAK-21 users could be all over this like flies on roadkill.
I have an ARAK-21 and run this. It’s excellent.
MDT also makes a folding stock adapter. It does not lock or even a detent to hold the stock in the folded position. ACE also makes a couple of versions of folding stock adapters.
Also Sig 556 owners can use them along with Faxon owners.
https://mdttac.com/folding-stock-adapter.html
Oh yeah, there’s no shortage of folding adapters out there. They’re just all big and clunky and/or more expensive in comparison. The SFU is the sleekest, cleanest one I’ve seen and it’s smooth as butter and locks up solid, so I’m definitely digging it.
There is a US company that sales almost the exact same part, has two allen screws on the 1/2 that attaches to the stock that the HERA does not have them. I had to look to make sure the one I have was not a HERA unit, cause I know I have not ordered from their US distributor. HERA also makes a HK SL8 stock adapter. I have non HERA one sitting here I was going to put on my new HS3 but it seems that a Savage 12 F/TR won’t work in that stock. Now have the MDT HS3 for a SA Savage with their Skeleton Rifle Stock but no action for it. Trying to figure out what to put in it.
And that company would be? I wanna buy!
Hey Ed, turns out it’s a white-labeled version of HERA’s part. So it’s made by HERA then the logo of the other company is slapped on (with permission). The design difference was due to it being an older version. The one reviewed here is the new version, and I do believe the only place to find it is LAN World, HERA’s U.S. importer/distributor…
Sent an email to the site’s email address with a link to the other company site. And an offer to take pics of the one I have sitting here.
so this will work just fine with my ARAK21 piston upper 🙂
Yes it will. I have an ARAK-21 upper and have been using it for months with the SFU.
bought a taurus 357 with shiny cylinder. took it to the range and the plating or shiny part of the cylinder mushroomed off after 5th shot and sliced my brothers neck about a inch from his juglar. I refuse to buy any revolver or gun that is shiny but that never stopped me from owning a taurus revolver. I just picked up another one 85 model 38+p love it. will always buy a tuarus.
I definitely don’t want to pay for the stamp to go sbr I just want a swivel arm brace do you think that it would work for just that ?? And do you recommend KAK or a Sig arm brace ??? On my cz scorpion !
Works great on my Kriss Vector
Nice to hear from another Vector owner out there. The safety switches don’t interfere at all, then? I’m THIS close to throwing a Hera SFU into a basket and pulling the trigger, but that clearance issue is the only thing that has been stopping me, as I have the Gen 2.1 version…
Bought it, got it, and installed it on the Vector. Fits and works, perfectly.
This appears to be the same thing as the XLR folding adapter. I can’t find any differences in appearance between the two. However this one seems to have bearings to somewhat lick it in the folded position.
The XLR is easy to buy. But I can’t find anyone who sells this SFU one.