That sure is what caused the damage. If you cant get a replacement lower from him then send me a message and I can make the lower for you. I just made some barrel band for another forum member and he is very happy with them. Here are some of the custom parts I make.
There is a good chance the O-ring got cut at the port when the valve was installed and is the first thing I would replace if you want to try and reseal the rifle. The damage on the wall is affecting the seal for holding air. Try to include some photos of the valve to show damage from the screws...
I have repaired stuff like this before and with damage on the wall where the valve goes definitely make your options limited. It is possible to repair but it most likely is cost prohibitive and a better option may be to just replace it. What happened when you spoke with the manufacture? can they...
If you are trying to avoid a lot charge to get the part anodized I would recommend some type of Cerakote. Cerakote looks great and it easier to control color and match other colors. I anodize all my custom parts and it can be difficult to match color shades and texture especially if you don't...
3D printed parts works great for a lot of stuff that no one makes or the parts are just to expensive for lower end rifles. It definitely has come a long way in the last few years.
Clearly a manufacturing defect on the frame because the damage is anodized. How can they not warranty it? The M4 was on my short list of possible new air rifles. Looks like my list is getting shorter by one. Thanks for sharing this.
I have a south bend 10" and they can be found for under 3K with lots of tooling. They are great for the home shop and will last forever. With a real professional lathe anything can be made on it including mill work with the proper attachments.