Hey peeps!
I’m a amateur gunsmith, and was curious about integrating an RFID security system into one of my new AR builds. If anyone has experience with this specific application, please get in contact with me.
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Let’s talk 
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FWIW, in the video where Amal indicated he had the antenna wouldn’t (and obviously didn’t) work. You’ll need to use a grip with an extended beaver tail and locate the antenna in it. The proper firing grip has the web of your hand jammed up as high as you can into the beaver tail, which is why the “standard” AR grip is crap. But, the aftermarket grips have a perfect location that would place the antenna directly in contact with a chip located in the web.
The Magpul MOE grip would be a good starting point.
Also maybe consider something along the lines of the Glock trigger safety that would manually lock the relay open after it was initially triggered with the chip. Only allowing the relay to close 1 second after the finger was removed from the trigger. That way it would help avoid the relay locking the gun up in the middle of a string of fire, but still safe it in the event it was taken away from you.
Actually looking into the AR-15 trigger group and grip you could realistically put the entire RFID assembly into the grip and drill a single hole for an actuator rod up behind the grip screw. A slightly extended hammer assembly, with a tab protruding behind the safety “barrel” could then be substituted. The locking bit would engage the trigger assembly just aft of and in a similar manner to the standard safety. No visible modification to the weapon, just a single hole drilled up into it, and completely reversible in 5 minutes by swapping out a nonRFID grip.
Well looks like there are a couple AR pros in the mix here… the ideal solution would involve a mechanical break in the linkage between trigger and hammer… so not something that blocks function, but something that enables function… instead of putting a pin in the way of the trigger or blocking linkage from moving, a pin is placed to complete the link. That way simple brute force can’t possibly overpower a blocking pin and cause the weapon to fire.
It’s been suggested that I create a modified trigger group for the PS90 that contains the reader and everything, then run an antenna up from there. It’s not always that simple, and the best antenna designs are difficult to get good reads of these pesky implants.
The question might want to start with include;
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Which frequency? 125khz puts up with a little more metal interference but antenna sizes are much larger than 13.56mhz.
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There are also NFC rings now which might expand options for users (they are 13.56mhz of course).
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Judicious use of “magnetic absorber sheets” in the antenna design might be a good idea. PDF1 PDF2
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If this is a one-off project, then consider developing a reader antenna to work with the flexNT vs the x-series… better performance. If either of you want to commercialize this, then design for the xNT or xEM since injections are a much easier sell than scalpel work.
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I was thinking some more. Although Amal likes the idea of an “actuate to fire” as opposed to “actuate to unsafe” (if that makes any sense) I can’t figure out how it could be done without a complete redesign of the FCG. There just isn’t any room in front of the sear as it’s all magwell.
My current idea du jour is to, instead of having only the single flat machined on the safety, machine a small 90* notch on the back bottom of the safety barrel and have the locking pin withdraw horizontally. The locking pin would both block the tail of the trigger from moving up, preventing firing, and it would also prevent the safety from being rotated. Doubly preventing firing. Then when the solenoid retracts the pin moving the safety to fire would rotate the remaining bit of the safety barrel into position to block the pin from coming back forward and jamming up the trigger in the midst of a firefight if the RFID read were to fail somehow. Which is my biggest gripe with the whole smartgun concept. What happens when the damn thing fails to read, locking my gun up with 3 bad guys running at me.
Ah… So you’re proposing a system that would lock or unlock the safety itself. I like it. Seems like an awesome balance between security and reliability.
I’d love to talk more about this. I’ll PM you.
@amal Would you be interested in selling or help developing such a system for the AR family of firearms? At the very least in limited numbers at first. (It would very much be in the “lab” territory for sure.)
Possibly, but at the moment I’m totally focused on VivoKey. Let’s chat in a few weeks though. I think I’d be much more willing to partner with someone who was leading that charge vs doing primary development.
Interesting and worthwhile watch. Particularly the bit about jamming the RFID signal.
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Meh… these are not issues with my PS90 project.
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sad I’m not at DefCon this year to talk to this guy… you’re right, it is interesting.
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the magnets work on the Armatix because it uses a solenoid to actuate a pin in the trigger linkage… my PS90 uses a servo… you can’t actuate a servo with magnets stuck to the outside of the gun.
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jamming or boosting the signal does not apply to passive magnetically coupled RFID systems… it only works with E field transceivers.
Yeah, not an issue with xNT or other technologies pertaining to this thread and DT in general. Just thought it was an interesting bit of information relating to smart guns in general.
I need to do more research on solenoids. I have 2 projects now that need to use them and have no idea about their capabilities. Off to Duckduckgo go I. (Because fuck google)
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I’m glad you already had a response to this as I just found the cnet article about the hack. I’m still not sure if I’d ever want to use a smart gun for a primary defensive weapon or not but I will be keeping an eye on this.
@I0TA This is a concept of what I was thinking of specifically when I mentioned the electrical components could be housed in the grip.
I think you could easily design an antenna that would fit in the overmoulded backstrap.
Correct. I don’t see this as having much application for military use, too much chance of failure and having your rifle fall into the wrong hands in a combat zone is a minuscule concern compared to electronics getting FUBARed and rendering you with a crappy club.
Where it has a lot of potential is in a home defense situation where, hopefully, your rifle will sit unused (except for recreational/practice) in an nice clean dry environment and never be used in anger. In that situation the risk of kids or some general idiot getting their hands on it and doing accidental damage is a much larger risk than having it jam up when some bad guy comes knocking.
@anon57259402 I think hat’s the trigger I sent on FB, and yes, a perfect example of the possibilities of electronics in the grip. Antenna in the beavertail where it would contact the chip directly in your hand (or glove for the needle averse), and actuate the solenoid either housed in the lower or house the solenoid in the grip and run an actuator rod through a hole drilled behind the grip screw.
I recently got my hands on the xEM access controller. It seems to be a RFID based car ignition immobilizer that was repurposed. I’m gonna try and reverse engineer the box, but it’d probably be a much more efficient idea to build a system from the ground up. I feel like theres a decent potential in the Arduino family of chips.
Using the safety detent spring hole isn’t a bad idea. The issue I see there is figuring out how to keep the safety from flopping loose when the pin is withdrawn. The detent pin is the only thing keeping the safety from falling out of the lower.
Also, using the M-16 selector is a no-go per the ATF. You’re not legally allowed to use any of the full auto FCG pieces in a civilian rifle. Dumb, and you’ll probably never actually get called on it, but there it is.
For the proto I’d definitely just buy one of the cheap automotive immobilizers off of eBay. I’ve had a similar one in my car for 13 years now with no issues. A cool feature that mine has is that it hooks into the driver door switch and only turns on the unit when the door is opened. It then looks for a tag for 30 seconds before going back to sleep. Hooking the door wire into a grip switch would keep the unit asleep and not drain the batteries when it sat in a corner for months at a time.
@I0TA When I say “MIL-SPEC” I’m referring to most semi auto FCG’s on modern AR models. (Basicly, using existing assemblies instead of redesigning the entire trigger package.)
You’re right when you say that that’s pretty much all it has to keep the selector from falling out. What about some sort of internal snap ring or “collar”?
Or you could just install an ambidextrous safety selector… That solves that problem right there now that I think of it…
Either way, I think it would require some custom manufacturing or at least modification to current selectors.
The only reason that the selector “holds” in the safe or fire position is that detent spring and pin. Perhaps making the hole in the selector for the “safe” position a little deeper so the pin can actually “lock” in place would work.
Or, I should say, instead of having just a straight pin going up into the safety decent, it could be positioned behind a small spring to give it a little “play” but still have tension on the pin.
When the unit “unlocks” it just retracts the pin or pushes it back.
Here are my $0.02 on the matter…
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use the existing safety as a power switch to the RFID lock. That way, the system is not constantly draining batteries sitting idle. When the user wants to use the weapon, they flip the safety to fire position. That powers the RFID reader, which instantly reads the chip and “unlocks” or “enables” (depending on which way you want to go design wise), and then you can fire.
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allow the user to select “fail secure” or “fail safe”. In door lock terminology, fail secure means if the system fails (batteries, malfunction, etc.) the door stays locked, but fail safe means the locks open and every door is passable (safe for people who might otherwise be trapped). With weapons, “fail secure” would mean you can operate the weapon, while “fail safe” means the weapon is disabled in the event of a system failure.
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discussing all this on a public forum will invalidate any patent rights you may want to explore… unless you filed within 11 months of the first mention of a patentable claim… which isn’t likely to happen… so be aware and maybe move this discussion to a private message thread if you want to retain those rights. This forum allows multiple users in a PM thread.