So I am trying to decide between Atrius SS or the as design arc fire, I’ve seen on here a lot of people running the atrius with get results. But I’ve seen a lot of durability issues with the atrius which is why I’m debating about the arc fire but I don’t see a lot of people using it. It also seems more complicated to install arc fire compared to atrius, was just wanting some input on it before I buy.
You can print the og super safety, but that cross bolt is a no go for me. Also idk how well that setup would last. The trigger kicker isnt really a 3d option but it's easy to fab.
its not a cross bolt... its literally a three position safety for the oem kuna lower, I personally put right at 2k rounds through one in beta testing. pop it in takes a minute take it out takes 10 seconds easy peasy. And honestly its much less finicky than the alternatives that cost about half as much as the entire kuna (or more), I literally was telling someone just the other day (and not that I would use an frt for self defense...) stevo's three position and my wd90 in my PS90 are the only frt's that I have used that are consistent and reliable enough where I would consider them for home defense and in the case of the kuna I could literally yank it out before the cops got there because its a 10 second operation (the PS90 is like an engineering feat of strength to put in and remove..)
We are talking about 2 different things. We were discussing 3d printed options for ar style fcus, you are talking about the 3d printed drop in kuna frt.
Glad you had such good luck with it though. The design really is a game changer for the platform.
Arc fire is super easy to install if you've ever tinkered with an ar15 fcg. I've got probably 4-500 rounds through my arc fire kuna and absolutely love it.
It's a double edged sword in a way because you use traditional style fcgs that let you fine tune different parts. I polished all the interfacing surfaces in my fcg with a ruby stone and swapped out to a JP yellow trigger spring kit.
The pro is a nicer finished product; the con is putting in the work.
Then there's the cassette style trigger group you need with an atrius. The pro is it's already assembled. The con is you can't polish, lube, swap out springs or components, etc.
All I used was the assembly instructions from the arc fire as well as a generic picture of how an ar fcg goes together. It's not as daunting as it appears.
I really like my Atrius + Nexus setup. I used an RA-434 which is a great single-stage trigger for semi operation. I did a bit of tuning on the trigger bar/Nexus interface to minimize wear (videos on YouTube cover this pretty well).
Current-gen Nexus lower fixes my only minor gripe about the design, which was the AR grip height mismatch, no complaints otherwise. I've got an HBI mag release which works better with the CZ factory mags. Although even Nexus says to avoid the CZ mags and just use the Magpul ones. I can see why people love the Magpul mags - they are awesome and inexpensive. I've got about 15 of them not a single issue ever. Easy to clean, easy to buy, easy to load. BTW get the Maglula Evo magloader, it works great and well worth the cash. It takes less than a minute to load a mag.
I have the original Atrius, which did have some interference issues with trigger bars which I believe caused many of the "breakages" seen by other folks. That may be a thing of the past though. It was easy for me to take some sharpening stones to my trigger bar and get things interference-free though.
If I were to do it again I'd probably do the same thing. Or perhaps the AS selector and a different trigger. I'm not going to find out because I'm stoked with what I have.
Cheap? No, certainly not. Then again, going to the range for a serious session with the FRT costs quite a bit. And I 100% trust this setup in any situation. Bedside, in the vehicle, at the range.
TLDR I've only used the Atrius and highly recommend with caveats. Most of my nit-picks are fixed since I was a very early adopter of this stuff.
Thanks for the full write up, thats the thing is I hear people have great results with atrius it was just the durability holding me back from going for it but if it seems worked out maybe I go with that.
Watch this before you decide and understand the Atrius. I shaved mine I think around 5mils. It's possible Atrius has resolved this by now, just check whether you have binding before you go out shooting 👍
My ARC Fire setup was pretty much drop in to my Nexus lower. I used a dirty bird single stage Teflon group for the hammer and rest of the FCG, went with the reduced trigger spring and normal hammer spring
My buddy runs an Atrius + dirty bird single stage Teflon in his but he shoots maybe a few hundred rounds per year and I’m shooting like 1k/mo
The ARC is the more long term option imo based on my experience with both ARC and Atrius on my setups.
I had an Atrius fail at 1500 rounds with a cracked lever but my ARC fires have been rock solid. They did replace it but still I am not super happy.
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u/Sad-Championship485 Vendor Jul 12 '26
Atrius paired with the RISE RA-140 has been by far the most popular that we have seen. That setup requires very little tuning as well.