Best Airline for travel with firearms?

Recommendations for domestic airlines that allows firearms?

Will be traveling primarily out of DFW.

i.e. DFW to Phoenix, DFW to Denver, etc.

I’ve flown a few times with firearms and so far United’s been the easiest for me at DFW. I booked through travelbusinessclass.com to get a cheaper upgrade to business, and the extra service made the check-in process way smoother. The agent actually walked me through the whole weapons declaration process without any hassle. Huge fan of how stress-free it was compared to past trips in economy.