Get accustomed to punching with the old-school, Okinawan fist. There’s a reason it’s done that way. Speaking from experience, if you actually punch a target like a bag or makiwara with any force, you’ll sprain your index finger(s). Likewise, you should have a slightly “knuckles up” feel to your punch, too, like these guys in the photos or your wrists will fold under hard impact. https://www.google.com/search?q=karate+punch+jka+nishiyama&tbm=isch&ved=2ahUKEwjRn7Th95T1AhUz8VMKHYzpBtYQ2-cCegQIABAC&oq=karate+punch+jka+nishiyama&gs_lcp=ChJtb2JpbGUtZ3dzLXdpei1pbWcQAzoECCEQCjoFCAAQzQI6BQghEKsCUJUcWIRVYJ9yaABwAHgAgAF0iAGUCZIBBDE1LjGYAQCgAQHAAQE&sclient=mobile-gws-wiz-img&ei=I5XSYZGCH7PizwKM05uwDQ&bih=1063&biw=834&prmd=ivsxn&rlz=1C9BKJA_enUS966US970&hl=en-US#imgrc=dytw5FsbE9JOBM https://www.google.com/search?q=karate+punch+jka+enoeda&tbm=isch&ved=2ahUKEwii876T-JT1AhUUMFMKHVeLBBcQ2-cCegQIABAC&oq=karate+punch+jka+enoeda&gs_lcp=ChJtb2JpbGUtZ3dzLXdpei1pbWcQAzIFCAAQzQI6BAghEAo6BQghEKsCUMaODFiO-w1gx4gOaAFwAHgAgAFfiAHVCJIBAjE2mAEAoAEBwAEB&sclient=mobile-gws-wiz-img&ei=jJXSYaL9IJTgzALXlpK4AQ&bih=1063&biw=834&prmd=ivsxn&rlz=1C9BKJA_enUS966US970&hl=en-US#imgrc=U-w3F3KewCjXTM&imgdii=Q19ygL3K9ON59M