After talking with the NATO Commander last night, I decided that I am going to attempt to build us a Heavy AT for Fulda

I was hoping for some help from everyone on here with the design and building of one.
I'm thinking of basing it off of my AT4 by extending the front tube with PVC, and then changing out the 150 psi relief valve for something around 300 psi to fill the chamber up more, thus giving it some more distance. If anyone has any suggestions on how to just build a homemade launcher I will go that route so that the AT 4 can still be used as a LAW.
As for the mounting. I'm thinking of picking up a set of 8 inch wheels from the local hardware store that come with a mounting bracket, and mounting them to a lazy susan from home depot so that the launcher will be on a swivel for the user. I would also like to mount a plastic plate of some sort on the front it so whoever is using it has protection from being hit, but I will have to look into how to do that. If anyone has any ideas please feel free to chime im here. I am thinking something like the six pounder in terms of protection of the user.
Advice, help would be amazing
