It really depends on a few things as far as I am aware:
1. I too am Methodist. As a Methodist, I was sprinkled during baptism. Many Churches will not accept sprinkling and require you to be immersed. If her church does not accept you as a 'sprinkled' Methodist, then they may not honor reciprocity.
2. Does her church have a minimum caliber requirement? A lot of churches will only allow calibers starting with a .4 and above. Make sure you and your girlfriend at least have that minimum requirement.
3. Is this a 'shotgun' wedding? If so, then the presence of a firearm automatically sets precedence and all other attendees may carry. Long guns may be carried openly, but you have to posses a CHL if you choose to conceal. Make sure to determine if the wedding is formal or not so you know if you must Duracoat your gun white before attending.
As an additional note; At the reception, some churches now require you to only perform the send-off 21 gun salute with steel shot. Lead shot is hazardous to the bride and groom in case they want to start a family.
Enjoy the wedding!!
P.S. Ammo boxes make great gift wrapping for shower gifts!!