Flux Defense and the Raider Family — from a Glock Brace to a P320 Chassis

The Flux Raider is usually described as a product. It is more accurately a lineage: a spring-deployed brace for Glock pistols, then a first chassis for the SIG P320 called the MP17, then a polymer chassis called the Raider, then a revised Raider X, then a Raider X with its optic hood cut off, with a P365 branch and two SIG factory pistols built around the same chassis along the way. The names overlap, the maker reuses them, and third-party pages routinely attach a feature of one generation to another.

This volume sets the lineage out from primary documents only: Flux Defense’s own pages as they stand on 19 September 2026, the same pages as the Internet Archive captured them in earlier years, SIG Sauer’s product pages and the operator’s manual SIG publishes for the Raider X, and the United States Patent and Trademark Office record. Where those documents are silent, the text says so.

The pistol that started this dive, a SIG P320-M17 in a Raider X, is documented part by part in the SIG P320-M17 dive, Volume 4. That dive owns the M17, the fire control unit (FCU) as the legal firearm, and the one existing build. This dive owns the chassis, and the planning of additional builds on it.

1.1 The Company, from Its Own Record

Flux Defense LLC is a Utah company. Its contact page gives “FLUX DEFENSE LLC” at “9091 S Sandy Parkway, Sandy UT, 84070”; the back cover of SIG’s Raider X manual, printed in 2024, gives an earlier address, “2618 S 900 W, South Salt Lake, UT 84119.” The footer on every Flux page reads “Copyright © 2019 - 2026.”¹²

The company’s pages do not name its founders, and no founding date is stated anywhere on them. Two primary documents come closest:

• The 2019 website. The earliest captured home page (23 July 2019) carries the slogan “Fight like an American,” a single product — the Flux Brace — and one contact address, [email protected], with “Flux Defense LLC, Utah, USA” beneath it.³
• The patent. United States Patent 11,156,433, “Brace apparatus for stabilizing a firearm,” names two applicants and inventors: Benjamin Latham Griffith and Arrius Lee Sorbonne, both of Salt Lake City. It claims priority to a provisional application filed on 26 October 2018.⁴

Those two facts are consistent with each other and with a company that began in 2018, but neither document calls anyone a founder, and this series does not. The inventors are named because the patent names them.

One more detail on Flux’s own FAQ is recorded without interpretation: export enquiries are directed to an address at rainierarms.com, the domain of another firearms business. Flux’s pages do not explain the relationship.⁵

Flux describes itself in one sentence: it “specializes in making duty-grade chassis systems that convert your pistol into PDW (personal defense weapon) style platforms.”⁵

1.2 Before the Raider: the Flux Brace for Glock

The first Flux product was not a chassis. It was a brace fitted to a Glock, sold from 2019 at $259.00. The maker’s product page, as captured on 26 August 2019, lists it as compatible with the “Glock G17 19X 22 31 34 35,” “Only compatible with Gen 4-5,” and gives its features verbatim:⁶

• “Auto-deploy”
• “High-strength, impact resistant polymer”
• “Chromoly steel with cerakote finish”
• “Works with Flux Holster”
• “single-pin quick installation”
• “Patent Pending Design. Flux Defense LLC.”

A Gen 3 version followed at the same price, and by 2021 Flux’s FAQ listed four: a G17 version, a G19 version, a FLUX HEAVY for the large-frame G20, 21, 40 and 41, and the Gen 3 version. An accessory called the Flashmag (later the Lightmag) held a weapon light and a spare magazine under the Glock’s dust cover.⁷

The Glock brace matters to this dive for two reasons. First, its patent is the Raider’s patent. US 11,156,433 describes a mounting housing with two lateral sides, two elongated bodies sliding in channels in those sides, a brace on the ends of the bodies, and a spring that drives the brace out when a locking member releases — the arrangement of every Raider since.⁴ Second, it is the source of a recurring confusion: Flux’s current pages still carry a Glock disclaimer and list “Flux Defense Glock Brace” and “Flux Defense Glock Flashmag” among their installation videos, which reads at a glance like a Glock Raider. No Glock Raider exists (see the last section of this volume).

1.3 The MP17 (2019)

The first P320 product was the MP17. Flux’s product pages as captured on 17 September 2019 offer two versions — “MP17 - Pistol Brace Version” from $399.00 and “MP17 - SBR Version (Coming Soon)” at $399.00 — and describe the concept in a phrase that has not changed since: “Drop your Sig™ fire control unit™ into the system.”⁸

What the maker listed for it, verbatim:

Table 1 — What the maker listed for it, verbatim

	MP17 (2019), from Flux’s page
Tagline	”Shoots like a primary, holsters like a pistol. 43 Rounds.”
Compatible	”Sig M17/18, Sig P320™ Full size, X-Five full size, Tacops Full Size”
Short slides	”To use the P320™ carry, compact, and subcompact, you must use a comp, threaded barrel, or suppressor or serious injury could occur.”
Capacity	”Holds up to 43 rounds. Carries an extra mag.”
Brace	”Patent Pending one-handed deployment. (Spring-loaded.)”
Optics	”Optic mount works with most red dot sights - RMR™, Holosun®, Deltapoint™ … It also works with a pic rail”
Holster	”Optional Duty Holster - Level 2 Retention”
Weight	”2.8Lbs (With full size slide - empty)“
Size, collapsed	”Height: 5.75” Length: 10.75” Width: 1.6””

The SBR version’s page carried a line that is still the correct order of operations: “This is the stock version. It will turn a pistol into an SBR. All NFA Regulations apply. You must Form 1 your fire control unit before installing.”⁹

Two things the maker’s MP17 pages do not state are the material of the chassis and how the 43 rounds are made up. The arithmetic of two 21-round P320 magazines plus one in the chamber gives 43, but that breakdown is an inference, not Flux’s statement.

1.4 The Raider, 2020 to 2023

The product that took the Raider name appears on Flux’s site by January 2021 as “FLUX RAIDER (Brace),” at $459.99, and its description introduces it as “the new MP17 Raider.”¹⁰ That phrase is the root of a naming problem that persists on Flux’s own pages: “MP17” is used for the 2019 product, and “MP17 Raider” or “Raider MP17” for the first polymer Raider. Flux’s 2026 accessory listings still use “MP17” to mean the original Raider — the stock kit is sold “FLUSH for MP17” or “FLUSH for X,” and the gas caps come in “MP17” and “X” versions.¹¹

What Flux listed as new on the Raider, verbatim from the 2021 capture:

• “New Injection-molded advanced Polymer developed to replace metal” (a later capture reads “to replace metal engine parts”)
• “Dual Mag Release system for lightning fast reloads (Patent Pending)”
• “Flared magwells.”
• “2X QD sling positions.”
• “More ideal optic mount height (pic rail)”
• “Spare battery compartment.”
• “New closed system for reliability against dust and debris.”
• “Dimensions 11”L X 6”H X 1.7”W”
• “Lighter: 18 oz (Chassis only) 40oz (assembled)”
• “Chrome Moly Steel. Nitride finish for maritime use.”
• “Now accepts larger diameter suppressors.”

Its compatibility list was narrower than today’s: “Sig M17/18, Sig P320™ Full size, X-Five full size … ( Will not work with Tacops or suppressor iron sights.)”¹⁰

Three episodes from the Raider’s life are recorded on Flux’s own pages and bear directly on anyone buying one second-hand or planning around the current model.

Supply. Flux’s 2021 FAQ describes a “polymer shortage,” restocks that sold out “in less than a minute,” and a decision to stop taking pre-orders because “we used to do pre orders and it took us almost a year and a half to get out of that hole.” By July 2022 the price had risen to $489.99, with the note that “Price has jumped up slightly for the first time since the launch of the product due to raw materials prices on our steel and polymer going up.”⁷¹²

The M17 safety. The same 2021 FAQ gave M17 owners a choice that Flux no longer offers: “You can either purchase and install the safety delete pin from Sig, or dremel out the notches on the Raider for the FCU safety levers. We included outlines on the Raider for dremeling. We recommend that you use the safety delete pin as it allows you to use our safety which is in a much more ergonomic location.”⁷ Flux’s current warranty is voided by “Removing safety notches” and its support page by “removing manual safety notches to accommodate the M17/M18 FCU safety levers.”⁵¹³ A second-hand original Raider may therefore have had its notches cut under the maker’s own earlier guidance. Volume 4 takes up what the safety question means for choosing a donor pistol.

The Raider Fix. In 2021 Flux published a notice at fluxdefense.com/raiderfix, captured on 4 September 2021:¹⁴

“WE’VE BEEN MADE AWARE THAT SOME RAIDERS ARE COLLAPSING UNDER RECOIL - ONLY ABOUT 4% - AFTER TESTING, WE FINALLY UNDERSTAND THE PROBLEM. … WE ARE MAKING REPLACEMENT LEVER KITS THAT ARE EASILY INSTALLED BY THE USER IN UNDER A MINUTE. WE WILL BE SENDING THESE OUT FOR FREE TO EVERYONE WHO HAS EVER PURCHASED A RAIDER - INCLUDING THOSE THAT PURCHASED SECONDHAND. … THIS FIX IS ALSO BEING IMPLEMENTED ON ALL UNITS GOING FORWARD. … THIS DOES NOT APPLY TO THE ORIGINAL MP17.”

The notice does not describe the cause beyond “the problem,” and no later Flux page was found that does. It is the only field fix of the Raider family located on the maker’s pages, and Volume 5 treats what it means for inspecting a used original Raider.

1.5 The Raider X, 2023 to Date

Flux’s own site data gives the Raider X product listing a creation date of 12 September 2023; the Internet Archive’s first capture of its page is from 27 January 2024.¹⁵ In May 2024 the page showed it sold out at $539.99 to $648.99 depending on configuration. On 19 September 2026 the same page shows $419.99, in stock, with only the three right-hand brace colours selectable by the public.¹⁶¹⁷ When the price fell could not be established.

Flux’s text calls it “a revamped version of the original Raider, with many enhancements, but keeping to the proven design,” and publishes — on the main product page in 2024, and in 2026 on its law-enforcement kit pages and the blemished-chassis page — a sixteen-item list of what changed. It is reproduced here in full because it is the only primary account of the difference between the two generations, and because the P320-M17 dive’s research recorded it as available only on retailer pages.¹⁸

Table 2 — The Raider X, 2023 to Date

#	Change, in Flux’s words	What it addressed
1	”Overtravel stop for magazines – Magazines can no longer be over-inserted.”	reliability
2	”Mold is now single gate instead of dual to decrease chance of knit lines (weak points), making for a stronger frame.”	strength
3	”Changed from pressed-in nut to molded in insert for the ejection spring bolt”	durability
4	”Improved dimensions to increase reliability of the various systems.”	reliability
5	”Stronger primary mag catch spring … clearer division between mag releases on the dual mag release system.”	reliability
6	”Dual mag release now has better fencing.”	reliability
7	”Increased rail-lock spring force for improved reliability.”	reliability
8	”Improved ergos around the top of the grip, improving access to primary mag release and safety levers.”	ergonomics
9	”Front of frame changed to allow for optional extended rails, allowing for increased LOP.”	ergonomics
10	”Improved magwells for easier insertion.”	ergonomics
11	”Improved grip panel texture.”	ergonomics
12	”Improved finish for decreased light reflection.”	ergonomics
13	”Suppressor cutout enlarged and improved for use with shorter barrels.”	compatibility
14	”Added pic slot on bottom picatinny rail for increased compatibility.”	compatibility
15	”Added slot to optic rail, raised it by 1mm and changed the front and rear ends, all to ensure full compatibility with all optics.”	compatibility
16	”Inside of slide channel under optic rail raised by 1mm for compatibility with adjustable iron sights.”	compatibility

Read against the Raider Fix notice, items 2, 3 and 7 are the interesting ones: a stronger moulding, a moulded-in insert where the ejection-spring bolt used to thread into a pressed-in nut, and more force on the rail lock — every one of them in the load path that the 2021 collapses ran through. Flux does not connect the list to the fix, and this series does not claim the connection; it notes only that the parts named are the same parts.

1.6 The Chop Top “El Camino” (2026)

The newest P320 chassis is the Raider X Chop Top “El Camino,” listed on 20 April 2026 at $469.99 and shown sold out on 19 September 2026. Flux’s description is one line: “our P320/M17 Raider X chassis with the non-reciprocating optic mount removed.” The features it claims over the standard Raider X are “Fits into smaller space (easier to conceal),” “Retain your slide mounted optic,” and “Lower optic height over bore.”¹⁹

Two cautions. The Chop Top page reuses the Raider X feature list, so it still says “Built in non reciprocating optic mount” a few lines below saying the mount has been removed — copied text, not a feature. And a Raider X owner who cuts the hood off a standard chassis to make the same thing voids Flux’s warranty, which excludes “Cutting or altering the optic mount.”⁵

1.7 The Factory Versions: SIG’s P320-FLUX Pistols

In June 2024 SIG Sauer began selling the chassis as part of a complete pistol. SIG’s P320-FLUX LEGION (SKU 320FLUX-9-LEGION) is described on SIG’s own page as “an all-inclusive P320-FLUX package … complete with a LEGION gray FLUX chassis, P320 FCU, LEGION skeletonized trigger, and integrated compensated LEGION slide”; a P320-FLUX TACOPS (SKU 320FLUX-9-TACOPS-TB) followed, with a black chassis, a Nitron slide and a 5.5-inch 1/2×28 threaded barrel. SIG lists both at 10.9 inches collapsed, 1.6 inches wide, 6.1 inches high and 49.2 ounces with magazine, at $1,399.99.²⁰²¹

SIG publishes the operator’s manual for these pistols under the title “SIG P320® RAIDER X™ OPERATOR’S MANUAL,” part number 1304128-01 REV 02. Its first mechanical section says: “The FLUX™ Raider X™ is a chassis system designed by FLUX Defense to be compatible with the P320® family of pistols to include the M17/M18 pistols.”² It is the only step-by-step installation, maintenance and function-check document published for the chassis by either company, and Volume 5 is built on it.

Flux’s FAQ confirms the relationship from its side — “The Flux Legion Raider uses the same chassis as the Raider X and supports all the same accessories” — with one difference that matters: the Legion’s ported slide “is not compatible with threaded barrels.”⁵

1.8 The P365 Branch

The Raider name also covers two chassis for the smaller SIG P365: the Raider 365 Aluminum ($599.99, listed April 2024) and the Raider 365 Ultralight ($399.99, listed November 2025, with a separate SBR variant), plus a sold-out limited “Raider 365 Sandbox.” They share the name and the brace concept but not the P320 chassis, and they differ from it on the one point this dive keeps returning to: “The P365 Raider models will work with the OEM manual safeties.”⁵ They are outside this dive’s scope beyond that sentence.

1.9 What Does Not Exist

As of 19 September 2026:

• No Glock Raider. Flux’s FAQ: the Raider “is currently available for the Sig Sauer P320 and P365 platforms, with the Glock and Ruger RXM versions on the way,” and, in answer to whether Flux will make chassis for Glock, “We are currently working on a version for Glock as well as a Ruger RXM version. There is no release date for either platform at the moment.”⁵
• No 10 mm version. “We will eventually have a 10mm Glock version. But there is no release date right now.”⁵
• No .45 ACP or P320 XTEN compatibility in the Raider X, which Flux and SIG both exclude.¹⁷²
• No “Raider 2.0.” The name circulates; it appears on no Flux page examined, current or archived.

1.10 The Patents

Flux’s patents page lists two, and they divide the Raider’s signature features between them:²²

Table 3 — The Patents

Patent	Title	Inventor(s)	Filed	Granted	What it covers on the Raider
US 11,156,433 B2	Brace apparatus for stabilizing a firearm	Benjamin Latham Griffith; Arrius Lee Sorbonne	28 Oct 2019 (provisional 26 Oct 2018)	26 Oct 2021	the spring-deployed brace on two sliding rails; Flux’s own patent
US 9,797,687 B2	Integrated optical sight mount	Trent Zimmer	21 Sep 2016 (provisional 22 Sep 2015)	24 Oct 2017	an optic platform rising from the frame on two side walls, with an opening “so that the slide assembly of the handgun is able to pass therethrough without interference” — the Raider’s optic hood

The second is the less obvious finding. Flux’s page describes it as “License Patent Unity Tactical, LLC: U.S. Patent 9,797,687.” The non-reciprocating optic hood, the Raider’s most distinctive feature, is the claimed subject of a patent Flux licenses, not one it owns.²³ The dual magazine release is described by Flux as “patented” and by SIG’s manual as a “Patented Dual Magazine Release system”; Flux’s patents page lists no separate number for it beyond “Additional patents pending,” and none was located.

For a machinist planning copies, the patents set a hard boundary that Volume 2 returns to: a United States patent runs twenty years from its filing date, so on their face these two run to about October 2039 and September 2036 respectively, subject to maintenance fees.

References

Footnotes

1. Flux Defense, “Contact Us.” https://fluxdefense.com/support/contact-us (accessed 2026-09-19). ↩

2. SIG Sauer, SIG P320 Raider X Operator’s Manual: Handling & Safety Instructions, P/N 1304128-01 REV 02 (©2024; PDF dated 25 April 2025), §2.1 and back cover. https://www.sigsauer.com/media/sigsauer/resources/FLUX_RAIDER_BRACE_OPERATORS_MANUAL_1304128-01_REV_02_WEB_UPDATE_1.pdf (downloaded 2026-09-19). ↩ ↩² ↩³

3. Flux Defense home page, Internet Archive capture of 23 July 2019. https://web.archive.org/web/20190723091317/https://www.fluxdefense.com/ ↩

4. US Patent 11,156,433 B2, “Brace apparatus for stabilizing a firearm,” Griffith et al., Appl. No. 16/666,240, filed 28 October 2019, granted 26 October 2021; provisional 62/751,117 filed 26 October 2018. Full image read from the USPTO: https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/11156433 (downloaded 2026-09-19). ↩ ↩²

5. Flux Defense, “Frequently Asked Questions,” items 1, 2, 11, 15, 24, 54, 58 and 60 quoted. https://fluxdefense.com/frequently-asked-questions (accessed 2026-09-19). Flux has renumbered this page since the P320-M17 dive cited it. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

6. Flux Defense, “FLUX Brace - 17, 19x, 34 ORDER NOW,” Internet Archive capture of 26 August 2019. https://web.archive.org/web/20190826001115/https://www.fluxdefense.com/shop/flux-brace ↩

7. Flux Defense, “FAQ,” Internet Archive capture of 2021. https://web.archive.org/web/2021/https://www.fluxdefense.com/faq ↩ ↩² ↩³

8. Flux Defense, “MP17 - Pistol Brace Version,” Internet Archive capture of 17 September 2019. https://web.archive.org/web/20190917001351/https://www.fluxdefense.com/shop/mp17-pistol-brace-version ↩

9. Flux Defense, “MP17 - SBR Version (Coming Soon),” Internet Archive capture of 17 September 2019. https://web.archive.org/web/20190917004302/https://www.fluxdefense.com/shop/mp17 ↩

10. Flux Defense, “FLUX RAIDER (Brace),” Internet Archive capture of 16 January 2021. https://web.archive.org/web/20210116202620/https://www.fluxdefense.com/shop/mp17-raider ↩ ↩²

11. Flux Defense product database (WooCommerce Store API, the maker’s own catalogue data), read 2026-09-19: SBR Stock Kit – Raider X P320; Gas Cap; Extra Parts Kit. https://fluxdefense.com/wp-json/wc/store/v1/products ↩

12. Flux Defense, “Flux Raider (Brace) – Sig P320,” Internet Archive capture of 8 July 2022. https://web.archive.org/web/20220708054241/https://fluxdefense.com/product/raider ↩

13. Flux Defense, “Support,” items 1, 4 and 8. https://fluxdefense.com/support (accessed 2026-09-19). ↩

14. Flux Defense, “Raider Fix Info,” Internet Archive capture of 4 September 2021. https://web.archive.org/web/20210904214915/https://www.fluxdefense.com/raiderfix ↩

15. Flux Defense site data, product 10722 (“Raider X P320”), field date = 2023-09-12T07:44:23, read 2026-09-19 from https://fluxdefense.com/wp-json/wp/v2/product/10722 ; first Internet Archive capture https://web.archive.org/web/20240127030931/https://fluxdefense.com/product/raider-x ↩

16. Flux Defense, “Raider X P320,” Internet Archive capture of 24 May 2024. https://web.archive.org/web/20240524102229/https://fluxdefense.com/shop/raider-x ↩

17. Flux Defense, “Raider X P320,” SKU X-RAIDER, $419.99. https://fluxdefense.com/shop/raider-x (accessed 2026-09-19). ↩ ↩²

18. Flux Defense, “RAIDER X FDE KIT – M17/P320” (SKU 161-00024) and “Raider X BLEM – P320,” improvement list quoted. https://fluxdefense.com/shop/raider-x-kit-m17-p320 and https://fluxdefense.com/shop/raider-x-blem-p320 (accessed 2026-09-19). ↩

19. Flux Defense, “Raider X Chop Top ‘El Camino’,” $469.99; listing date 2026-04-20 from the maker’s site data. https://fluxdefense.com/shop/raider-x-chop-top-el-camino (accessed 2026-09-19). ↩

20. SIG Sauer, “P320-FLUX LEGION,” Internet Archive capture of 27 July 2026 (sigsauer.com refuses automated requests). https://web.archive.org/web/20260727211102/https://www.sigsauer.com/p320-flux-legion.html ; first capture 25 June 2024. ↩

21. SIG Sauer, “P320-FLUX TACOPS,” Internet Archive capture of 19 July 2026. https://web.archive.org/web/20260719121746/https://www.sigsauer.com/p320-flux-tacops.html ; first capture 1 October 2025. ↩

22. Flux Defense, “Patents.” https://fluxdefense.com/pat (accessed 2026-09-19). ↩

23. US Patent 9,797,687 B2, “Integrated optical sight mount,” Zimmer, Appl. No. 15/272,372, filed 21 September 2016, granted 24 October 2017; abstract quoted. https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/9797687 (downloaded 2026-09-19). ↩