AS Designs Super Safety MP5 Lower: Making Haste

I hit the range with AS Designs’ ARC-Fire Super Safety MP5 lower to see just how fast a semi-auto can go.

If you haven’t heard of the Super Safety by now, you’ve been living under a rock. The clever little gadget is capable of massively increasing a gun’s fire rate while still meeting the legal definition of semi-automatic, i.e., one round fired per pull of the trigger. More on that later.

All you need to know is that they’re federally legal at the time of writing and, if you own an MP5, there’s not a single better upgrade you could get for it than AS Designs’ Super Safety MP5 lower.

AS Designs Super Safety MP5 Lower

You may be asking yourself, why do you need a whole new MP5 lower? Aren’t Super Safeties just triggers? They are triggers, but they’re AR-pattern triggers, meaning to run in an MP5 you’ll need a redesigned lower to accommodate one.

While this is an added expense, the upside is that it also massively improves the ergonomics and trigger feel of the MP5.

I only got on board the MP5 train relatively recently, but I absolutely love the platform now. My AP5SD quickly became my favorite gun to shoot. Right off the bat, though, I felt it was lacking in certain departments. AS Designs’ MP5 lower fixes all of them.

Firstly, it’s compatible with standard AR grips and therefore provides familiar AR ergonomics. Secondly, because it now uses an AR trigger, even if you were only using it in standard semi-auto mode, it would still be a major improvement over the original notoriously long and mushy MP5 trigger. AS Designs’ MP5 lower can even accept a ton of great aftermarket trigger options, but I found the mil-spec trigger in mine to be more than adequate.

Finally, the MP5 was simply born to go fast, and like most PCCs, it feels absolutely neutered when limited to standard semi-auto fire. Thankfully, the increased fire rate of the Super Safety semi-auto mode remedies that.

To reiterate how Super Safeties work, each shot fired requires its own independent trigger press. The trigger is just being forcefully reset at such a high speed that you don’t consciously notice that it’s happening when firing. Slow-motion camera footage reveals the truth, but when you’re behind the gun, it feels like the real deal.

ARC-Fire

I’ve been referring to the AS Designs trigger in my AP5SD as a Super Safety, but technically, the version I’ve been testing is the company’s ARC-Fire model. The difference? Instead of a 3-position push-button safety, it uses a standard 3-position AR selector. Not only is that an improvement over the original Super Safety design, but also a big upgrade over the MP5’s original stiff and hard-to-reach selector. 

Buying the ARC-Fire version of the MP5 lower is $100 more than the standard Super Safety version, but I think it’s well worth it.

Is This Legal?

Yes, at the time of writing, Super Safeties and other similar fire rate-enhancing products that forcefully reset the trigger between each shot are legal. I can’t spell it out as clearly as AS Designs does, so here’s the company’s answer to the question straight from their website:

• Are the Super Safety and ARC-Fire legal?

• According to current legislation and federal court, yes. This requires a single action of the trigger for each shot fired, then the BCG forces it into safety which resets the trigger moving it forward, then the BCG moves it back out of safety as it chambers the next round, then the trigger may be activated again. A key step in this process is that the disconnector engages the hammer during the cycle, it does not defeat the disconnector, prevent it from engaging, or replace it. The recent federal court settlement between the ATF and RBT has defined that forced reset triggers are NOT machineguns (National Association for Gun Rights, Inc. v. Garland (4:23-cv-00830)).

• However, if you live in a state with laws against forced reset triggers or “rapid trigger activators”, you can’t possess the Super Safety or ARC-Fire (look up your own laws please, but it should be CA, CO, CT, DE, FL, HI, IL, MA, MD, MN, NJ, NV, NY, OR, and RI that have laws against them). Also, please respect any ranges that you visit that may have rules against these.

Installing The Super Safety MP5 Lower

Thankfully, getting your MP5 set up with AS Designs’ Super Safety or ARC-Fire system is even simpler than doing so with an AR-15. The AR install isn’t too hard either; it’s basically just a trigger and selector swap, but it is more time-consuming than this.

Since the Super Safety MP5 lower comes fully assembled, all you have to do is remove your standard lower and replace it with AS Designs’. Since the upper is the serialized portion of an MP5, this poses no legal issues and the new lower can ship straight to your door.

The only other part of the process is installing a component called the Slip Trip on the rear of your bolt carrier group. Once on, the carrier is reinstalled into the upper and the lower can be reattached while ensuring the reset lever is between the back of the carrier and the Slip Trip. It’s a bit hard to convey through words and photos, but there are videos online you can easily find that will show you exactly what to do. All in all, it’s a very quick, easy and completely reversible process that requires no permanent modifications to your gun.

It’s also worth noting that the lower is available for what I think is every 9mm MP5 clone available on the U.S. market, but you’ll need to make sure to order the right variant for your model. I was testing the AP5 version on an AP5SD, and they mated up perfectly.

At The Range Knee-Deep In Brass

Boy oh boy, this baby is fun. Words can’t do it justice.

The three-position ARC-Fire selector works as fast and smoothly as it does on an AR, the trigger in standard semi-auto is just as nice as an AR’s, and as for Super Safety/ARC-Fire mode? Let’s just say that everyone that I’ve brought to the range to try it was grinning ear to ear after emptying their first mag. A full 30-round mag dump only takes a couple of seconds, by the way, but sometimes that’s all it takes to leave someone satisfied.

As for handling? That’s more up to the MP5 design itself, but it was built for this kind of fire rate and is legendary for its low recoil and excellent controllability, so no surprise the AP5SD felt the same when switched to ARC-Fire mode.

Its reliability was impeccable as well. In nearly 1,500 rounds of shooting in ARC-Fire, I only had two stoppages caused by the trigger failing to reset. That’s a damn good track record. The vast majority of that shooting was done with HSL 147-grain subsonics, but some various supersonic loads were thrown in the mix as well.

The only bug I ran into was at around the 1,000-round mark when I noticed the ambi selector switch had started to work itself loose. AS Designs almost certainly uses thread locker to install these parts at the factory, but after a lot of rattling, mine still started to back itself out. Thankfully, I caught it before it got lost and was able to simply reinstall it using more thread locker and elbow grease, and it stayed put just fine for the next 500 or so rounds since. That said, this is definitely something you’ll want to periodically check after shooting.

I keep emphasizing how much fun the ARC-Fire MP5 is, and while that’s true, I have to point out its practical benefits as well.

We all know that guns chambered for intermediate cartridges like AR-15s are really more useful 90 percent of the time in true semi-auto mode, and that’s how militaries train soldiers to use their rifles in most situations. That said, if there’s any class of gun that can practically benefit from an increased fire rate, it’s pistol-caliber carbines. This setup proved that with how easy it was to put controlled bursts of relatively tight groups on target.

If you’re thinking about getting your first Super Safety, I’d recommend doing it for a PCC before something like an AR-15. That said, MP5 clones aren’t your only option, as AS Designs has models that fit AR-9s, MPXs, Kunas and more.

Parting Shot

AS Designs’ MP5 Super Safety lower took my favorite gun and instantly made it about 10 times cooler. Not a lot of accessories on the market can do that. We’re living in a pretty amazing time when these are currently legal, now we just have to hope it stays that way. While these devices in no way meet the NFA’s definition of a machine gun, and a federal court ruling agrees with that, you never know what constitutional infringements the future may hold.

There’s a bunch of different options on the market, but AS Designs’ MP5 solution has left me incredibly impressed. If you buy one, just get ready to buy a shitload more ammo. You’re gonna need it.

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