I'm not sure the Evolve feedneck will fit a Proto, the threading is the same though.
The Proto's feedneck threading is set quite far down into the gun itself, and as such the feed tube has to be longer in order to reach it. If its too short, the feed neck may only be held on by a turn or two, and can strip quite easily. It was a very common problem when the Proto first came out.
The Hybrid Hedlok2 worked perfectly on my Proto! (before I sold it
)