A Homemade 1.25kJ Coilgun

    This homemade coilgun is very impressive.

    There has been a debate on AR15.com about how powerful this gun is. My guess would be a 800 grain slug traveling at 100 ft/second and generating just under 18 ft/lbs (24 joules) of muzzle energy. This is guesstimate fits in with the inventor’s estimate of 1-3% efficiency (1250kj * 0.03 = 37.5 joules).

    This gun would still have recoil. Newton’s third law of motion cannot be circumvented by the use of magnets. Please correct me if I am wrong (UPDATE: I am!), but I think the recoil would be spread out during the time the projectile passes through the “barrel” (magnetic coils), unlike a firearm where the recoil occurs after the bullet exits the barrel. A marksman would need to counteract the recoil whilst aiming the gun, much like a machine gunner. This would have a horrible effect on accuracy, but the felt recoil would probably be more comfortable.

    [ Many thanks to Ben and jdun1911 for emailing me the link. ]

    Steve Johnson

    I founded TFB in 2007 and over 10 years worked tirelessly, with the help of my team, to build it up into the largest gun blog online. I retired as Editor in Chief in 2017. During my decade at TFB I was fortunate to work with the most amazing talented writers and genuinely good people!