What is the threading on the buffer tubes of KJWs? If its real steel threading, than either a real steel or WA stock will work on it.
As far as SR25s go... No sir. In airsoft, there are actual SR25s. I had one. They are gorgeous; definitely not just an M4 body with a big RIS and fixed stock.
Look up pics of the G&P SR25, or the CA25, or G&G GR25. Cool stuff. What you want to make is like a SAM-R, or standard DMR
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