Springfield Kuna Scorpion-Mag Lower Upgrade: Nexus Firearms Fixes the Biggest Problem
Welcome back to Major Pandemic’s Bunker Bar, the cold-world underground hideout where the wine list is deep, the liquor never ends, and the gear talk gets brutally practical. This episode is all about one of the most exciting upgrades to the Springfield Kuna platform: a billet lower receiver from Nexus Firearms that lets the Kuna run CZ Scorpion magazines and AR-15 fire control components.
The Kuna’s “three big gripes” out of the gate
The Kuna showed up looking like a premium PCC: roller-delayed, high-quality billet upper, and a price point that made people pay attention. But three complaints surfaced immediately:
Proprietary magazines
The Kuna mags are affordable and reliable—but they’ve been consistently hard to find. When owners can’t buy extra mags, the platform’s long-term appeal takes a hit fast.Proprietary trigger system
The factory trigger is described as good for a PCC, but the bigger issue is being locked into a proprietary trigger format instead of the massive, proven AR trigger ecosystem.Polymer lower on an otherwise premium-looking gun
Even if the polymer lower is durable and lightweight, a billet upper paired with a polymer lower creates a mismatch for buyers who want a truly “premium” feel.
Nexus Firearms delivers what people wanted
Nexus didn’t just offer one solution—they offered two lower receiver options:
AR-style controls with a push-button mag release
Scorpion-style paddle mag release for those who prefer the classic Scorpion manual of arms
The big win: both versions take CZ Scorpion magazines, which instantly solves availability, capacity, and ecosystem headaches—especially for anyone already sitting on a pile of Scorpion mags.
Why Scorpion mags are the practical upgrade
Switching to Scorpion mags isn’t just about preference—it’s about logistics. The episode highlights:
Better magazine availability
More capacity options (including 35-round patterns)
Similar pricing to Kuna mags, but without the “always out of stock” issue
It also recommends Magpul Scorpion mags as a dependable, consistent option versus some OEM variability.
AR triggers change everything
By moving to an AR-spec fire control group, the platform becomes dramatically more flexible. Instead of being locked into a proprietary Kuna trigger, you can now choose from the enormous universe of AR triggers—whether that’s a crisp duty trigger, a competition unit, or simply swapping setups over time without special proprietary parts.
This is a major “future-proofing” move: triggers evolve, tastes change, and the AR ecosystem is the most supported trigger ecosystem in the country.
Looks, feel, and performance: “This makes it look like a $2,500 gun”
One of the strongest takeaways is how much the billet lower changes the Kuna’s presentation. With billet on billet, the gun reportedly looks and feels like it belongs in the same “premium PCC” visual tier as platforms like the MPX or higher-end European options.
Reliability feedback is also clear: several hundred rounds—including low-grade range ammo—ran with zero malfunctions. The ergonomics were praised, and the overall system stayed “flawless” after the swap.
Minor downside and a quick fix
Two small notes:
You lose the left-side ambi mag release found on the original setup.
The AR-style paddle mag release spring tension was considered too light on the early sample.
The spring issue was solved quickly by adding additional spring tension, and the expectation is that production refinements will address it cleanly.
The value argument: “This is worth the price of 10 mags”
With the lower priced in the mid-$300s range (depending on mag release style), the episode frames the upgrade as a smarter investment than chasing hard-to-find proprietary mags. If you already own Scorpion mags—or want the security of widely available mags—this upgrade is positioned as the obvious path.
Bottom line
If you love the Springfield Kuna but hate proprietary limitations, this Nexus Firearms lower is the upgrade that turns the Kuna into what many shooters wanted from day one: Scorpion mag compatibility, AR trigger flexibility, and a truly premium billet look—without sacrificing reliability.
