Which Namco arcade gun model is it?
How did you melt it by the way with the overvoltage?
You used it too much like that or hold it pulled for too long?
On AliExpress also you might have some luck finding one.
I got a Chinese full Time Crisis 4 enclosure on Ali before, and while the case isn't as good as the real gun, the recoil itself seems to be quite similar as the original.
It's also worth noting that namco isn't officially selling their gun parts to end customers. Meaning anyone selling those parts are either selling Chinese replacement parts and/or aren't certified sellers. So no matter where you get it from, it has big chances of being the same thing, only different prices.