I have go along with the consensus here and say use what you have.
Being a former LEO, Sheriff's Deputy, we had to qualify with whatever firearm we would use on duty. We were advised and have advised people, that asked how many times should they shoot someone that was attacking them. I heard the Chief deputy tell some civilians training for an armed car company, that if ever in a situation where you're endangered, empty your firearm into them. There was woman who thought that wounding them would be better. She was told," In any shooting there is going to be an investigation, Hearings go quicker when there is no survivors testimony. If you empty your weapon in the bad guy it appears that you were in desperate fear for your or your families life. A wounded bad guy can come after you later, a dead bad guy can't". In my opinion anyone invading my home and threatening my family is committing suicide. Killing a man is a terrible thing but in selfdefense there should be no remorse.
I too would use a 12 gauge if I had one.
I have noticed also how many Seals, snipers, and Special Forces people post in some forums. Kind of like the number of people who throw away any rifle that doesn't shoot 1/2MOA.