Each barrel, bolt, and lock block, are fitted as a set to function reliably and safely. We inspect each set to ensure it passes a headspace check that is a must do for safety.
Selling a stand-alone barrel could cause malfunctions with your Mongoose.
To ensure continued reliability of the gun, we suggest taking your Mongoose to a reputable local gunsmith and have the barrel threaded. ½-28 is a suggested thread standard.
We will sell the Mongoose flat-end cap separately and hope to have it available early Q1 - 2025.