The Serbu RN 50 is a budget break action .50bmg rifle originally designed by YouTuber Royal Nonesuch. He collaborated with Serbu and they made the RN50. Pictured above is a shorty version. It is not available on their website but one was made for Royal Nonesuch. It has a 16″ barrel and has a folding stock adapter. It looks very tiny. I kinda want one now.