Keyframe swapping question

[area34]

I'm sure this is an easy question to answer but damned if I can figure it out. Last night for for no reason at all i was trying to get a melee animation to be a ranged animation with with nifskope. I eventually through trial and error got an animation to swap but somehow the a ranged attack became a melee instead of vice vesrsa. I've tried off an on today to recreate what I did but in a different order so they would be swapped correctly but every time I run the character in ffx or cctool it crashes the program out so I don't know if what specifically I'm doing differently this time is whats killing the keyframe or if what i'm doing is just not allowed.
So after all that.. my question is, does someone have a workable method for  to swap/copy melee animations to ranged animations?
thanks in advance to any one who can help.