I have a new breech available. It is a direct replacement for the stock plastic breech. It uses all the stock parts. You just unbolt your stock plastic breech and install this new alum one. There is no need to unscrew the bolt from the cocking knob. They are machined out of alum and anodized black. They have a 3/8 dovetail and a set screw to secure the barrell. The breech will be $35 + $3 shipping. email me for ordering info. email@example.com
Here is a short video of how the bolt is installed.
My other project: