Need help finding a part

Hello! I recently got a hold of an AR15 7.62 upper. I started to piece the whole firearm together but I am in need of a replacement charging handle. I haven't been able to find one so far, including on the manufacturer's site (Palmetto), even though it appears to be a simple screw-in piece. Does anyone know where I can order the right part?
Maybe I'm using the wrong search parameters?

Thanks!