Not a custom body, but I have a slug body you can have machined into what you want.
Sounds more like a body o-ring (#31 in the pic below). Even if it's new, sometimes it just doesn't fit right, especially with aftermarket regulators.
Yes, you could hear it, but if the problem is happening with both on/off assemblies, then you're right. It's probably something else like the sear sticking,