Not sure but it seems that the NRA agreed to the legislation with minor changes that really have no effect on the law as written. Why go from 100% against it to 99% for it with a 1% change in wording that is almost meaningless?
http://rt.com/usa/154116-nra-huffpost-domestic-abuse/
http://rt.com/usa/154116-nra-huffpost-domestic-abuse/