My second Thompson Coilgun Model is allmost twice as efficient as the first, and all I did was made the Coil Legnth shorter by 1/2 of modedl1. This would put the same amount of magnetic flux on a smaller area, intensifying the force on the steel rod and projectile. Also I had madee the wire legnth slightly longer by 6ft, my purpose here was to try and increase the pulse legnth slightly effecting the projectile for a longer duration.