STEN Gun GBB Upgrade Guideline

The upgrades of the STEN Gun series are outlined below.
These changes were introduced in different versions over the years, which are noted accordingly.
Upgraded components:
1. Nozzle
2. Hop-up chamber
3. Valve knocker assembly
4. Magazine gas route

#2018_Version, the original design:
Short nozzle tip, tight hop-up chamber, rearward-positioned valve knocker, and a wide gas route.
Models:
STEN Gun GBB, Mk.II, Early
STEN Gun GBB, Mk.II, Late
STEN Gun GBB, Mk.II(S), Skeleton Stock
STEN Gun GBB, Mk.V
STEN Gun GBB, Mk.II, Long Branch, T-Stock
STEN Gun GBB, Mk.II, Chinese Contract (Lend-Lease Program, DNA distributed)
STEN Gun GBB, Mk.VI

#2020_Version, the accuracy-improved design:
Long nozzle tip, improved hop-up chamber, rearward-positioned valve knocker (same as the 2018 version), and a wide gas route (same as the 2018 version).
Models:
STEN Gun GBB, Commando Grip, SOE WelSilencer
STEN Gun GBB, Mk.II, BSA, Skeleton Stock
STEN Gun GBB, Mk.II, BSA, T-Stock

#2024_Version, CO2-ready upgrade:
Long nozzle tip with a wider loading bar, an updated hop-up chamber designed for the wider loading bar, forward-positioned valve knocker assembly, and a shortened gas route.
Models:
STEN Gun GBB, Mk.II, BSA, Skeleton Stock
STEN Gun GBB, Mk.II, BSA, T-Stock

Upgrading a 2018 STEN Gun to the 2020 configuration:
1. Upgrade to the 2020 nozzle (available).
2. Upgrade to the 2020 hop-up chamber (discontinued).

Upgrading a 2018 STEN Gun to the 2024 configuration:
1. Upgrade to the 2024 nozzle (available).
2. Upgrade to the 2024 hop-up chamber (available).

Notes for Existing Owners:
For owners of the 2020 STEN Gun: Nyet! Rifle is fine!
For owners of the 2024 STEN Gun: If your nozzle is damaged, we will provide a free replacement nozzle.

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