Flying through LHR with firearms

[Franco]

I have a leopard hunt booked for June/July of 2025 (hoping to complete the Big 5) in Mozambique. As it appears JNB to Tete is the only viable option, I am looking at options for DFW to JNB. In the past I have flown thru both Doha and Dubai on QATAR and Emirates. There is an American/British Airways option transiting LHR, which as a retired AA offers some benefits. Does anyone have recent experience traveling thru LHR with firearms?

Also, any alternatives to JNB to Tete?

Thank you