Yes unfortunately the dmg calculations for Throw is indeed way off. If you use Fort, the numbers are even more skewed. The actual dmg is about 1/3 of display dmg..in your particular case, 4k is about what you are actually doing..which is nothing to laugh at by any means.
I am not sure what the formula is for throw dmg calculations, but I am hoping someone here does and is willing to pass on the info.
If you can get your hands on a pair of lacerators( eth would be juicy great!), you will find the amp dmg will greatly help your cause. Have fun with it!