FN P90/PS90 Stock Extension (Gen 4)

Product Description

The Haga Defense Gen 4 Stock Extension for the FN P90/PS90 adds customizable length to the factory stock in 1", 2", 3", or 4" options, allowing shooters to achieve the perfect length of pull for improved comfort and control. Manufactured from durable MJF nylon, these extensions reuse the factory buttpad for familiar non-slip performance. The 3" extension is ideal for Maryland compliance, and the 4" for California, meeting state-specific overall length requirements.

Specifications

• Material: Durable MJF nylon
• Lengths Available: 1", 2", 3", 4"
• Weights: 1" – 3.9 oz; 2" – 6.0 oz; 3" – 8.1 oz; 4" – 10.3 oz
• Included: Stock extension, mounting hardware
• Made in: USA

Compatibility and Installation Notes

• Compatible with all FN P90 and PS90 models
• Reuses factory buttpad
• 3" extension optimized for Maryland OAL compliance
• 4" extension optimized for California OAL compliance
• No permanent modifications required

Installation Instructions

1. Safety First: Before beginning installation, make sure the firearm is completely unloaded, the chamber is empty, and the safety is engaged. Remove the magazine, visually and physically inspect the chamber to confirm it is empty, and point the firearm in a safe direction at all times.
2. If not already done, pull the cocking handle completely rearward and then release it. This operation is necessary because it is only possible to remove the moving parts group and the hammer group when the hammer is at the (lowered) cocked position. From now on, do not pull the trigger : the hammer would again be positioned at its (raised) decocked position.
3. While pushing down on the barrel support lock, release the barrel support and upper rail group by moving it slightly forward and then slide it completely out of the frame.
4. Release the moving parts group by pushing it forward (via the magazine opening) and then carefully slide it completely out of the frame.
5. At the rear, slide the butt plate up and off the frame.
6. Slide the butt plate onto the new extension the same way it fits the factory stock.
7. The extension includes a pre-installed 1/4"-20 internal set screw used to lock the butt plate in place. Use the included 1/8" hex wrench to tighten the set screw until the butt plate can no longer slide upward. Be careful not to over-tighten the set screw as this can damage the extension.
8. With the butt plate secure, slide the extension onto the rifle the same way you would the factory butt plate. If the extension seems too tight going onto the gun you can loosen the screws in the rear of the stock to allow it to slide on easier. Retighten them once in place.
9. Slide the moving parts group back into position. This will lock the extension in place.
10. Re-install the barrel support and upper rail group into the frame. Press the barrel support lock to start sliding the assembly into the frame and continue until it locks into place.
11. After having reassembled the firearm with an empty magazine, point it in a safe direction and then pull the trigger in order to decock the hammer. Before carrying out this step, ensure that the magazine and, of course, the chamber are really empty!