The NRA supported the FOPA which included the Hughes amendment.
The NRA did not want the Hughes amendment.
They stated that it was "railroaded through in the closing minutes", called it a "bad amendment", stated that they did not compromise or sell out on that amendment to ensure passage of the entire FOPA. In other words, there was no deal made to allow the amendment or support it after it was made.
It's fair and accurate to state that the NRA didn't outright try to kill FOPA once the Hughes amendment was added, but it's inaccurate to make it sound like the NRA wanted or supported the Hughes amendment in any way, shape or form.
They were under the impression, at the time, that they could get the amendment repealed after passing FOPA and worked toward that goal for some time (funding some court cases and lobbying) before determining that they could not garner any support in Congress to make it happen.