Springfield Armory Kuna .40 S&W – Strike Industries FSA, Black (KN90640B-FSA)
The Kuna in .40 S&W with the factory Strike Industries FSA folding brace is Springfield’s roller-delayed PDW built for control in a short package. Monolithic aluminum upper, integral M-Lok handguard, hybrid flip-up sights, multi-port muzzle brake, and two 30-round magazines. Springfield part KN90640B-FSA, UPC 706397988975. This listing is for the .40 S&W Strike Industries FSA configuration only.
Roller-Delayed .40
Springfield’s roller-delayed system locks the bolt briefly before unlocking, cutting reciprocating mass versus a heavy blowback bolt. On a .40 S&W PDW that matters for follow-up shots and muzzle control.
Strike Industries FSA Brace
This SKU includes the Strike Industries FSA single-side folder on the Picatinny receiver end plate — fold it for storage, deploy it when you want a more stable shooting position. Overall length spans 15.5" to 24.5" depending on brace position.
Barrel, Brake, and Controls
- 6" cold radial hammer-forged Melonite barrel, 1:16 twist, 9/16x24 muzzle threads under the multi-port brake
- Flat aluminum trigger; AR-pattern grip with adaptive texture
- Reversible, non-reciprocating charging handle; ambidextrous safety
- Hybrid flip-up metal sights on a full-length Picatinny top rail
Springfield Armory Kuna Specifications
| Manufacturer | Springfield Armory |
| Model | Kuna Pistol, Strike Industries FSA |
| Part Number | KN90640B-FSA |
| UPC | 706397988975 |
| Caliber | .40 S&W |
| Color | Black |
| Barrel | 6" Cold Radial Hammer Forged, Melonite, 1:16, 9/16x24 |
| Operating System | Roller-Delayed |
| Upper Receiver | Monolithic Aluminum, Type III Hardcoat Anodized |
| Lower Receiver | Injection Molded Glass-Filled Polymer |
| Handguard | Integral, M-Lok |
| Pistol Brace | Strike Industries FSA |
| Trigger | Flat Aluminum |
| Muzzle Device | Multi-Port Muzzle Brake |
| Receiver End Plate | Picatinny |
| Charging Handle | Reversible, Non-Reciprocating |
| Safety Switch | Ambidextrous |
| Sights | Hybrid Flip-Up |
| Grip | AR-Pattern w/ Adaptive Grip Texture |
| Magazines | (2) 30-Round |
| Weight | approximately 85 ounces (5 lbs 5 oz) |
| Length | 15.5" – 24.5" |
Frequently Asked Questions
Is this the 9mm Kuna?
No. This listing is the .40 S&W Kuna with Strike Industries FSA — KN90640B-FSA only.
Does it include the folding brace?
Yes. Springfield lists the Strike Industries FSA on this SKU.
How many magazines ship with it?
Springfield publishes (2) 30-round magazines for this configuration.
What barrel length does Springfield list?
Springfield’s product page lists a 6" cold radial hammer-forged Melonite barrel for KN90640B-FSA.
Internal Reference:
KN90640B-FSA
Barcode:
706397988975
| Brand: Springfield Armory |
| Model: Kuna |
| Caliber: .40 S&W |
| Capacity: 30 |
| Color: Black |
| Barrel Length: 6" |
Check Shipping Availability
This product may have shipping restrictions in some states.