I used 500 grain Barnes TSX my friend
Ah. I strongly discourage using Barnes X bullets for hunting lions. These monometal bullets need to be pushed to rather high speeds in order to expand rapidly/reliably and they will frequently fail to expand properly on lions (even more so for one that is shot over bait).
My preference is for old fashioned lead cored bullets with a copper/gilding metal jacket which will expand quickly on lions. But the bullets must still be well constructed (with bonded cores being even better), because the bullet must still be able to hold together so that it can penetrate well. The chest muscles of a charging African lion can best be compared to tyre rubber (which you now have personal experience with). My favorite lion bullet of all time is actually the Nosler Partition (but they have become virtually impossible to find now, as Nosler doesn't appear to have manufactured any new consignments in the last 2 years or so). Among currently manufactured bullets on the market, my choice would be for Swift A Frames.
If you decide to purchase another double rifle in the future with the purpose of lion hunting in mind, then I will strongly recommend a .500/416 Nitro Express. It launches 400Gr bullets at 2330fps. Lion you see, have a highly developed central nervous system that is extremely susceptible to hydrostatic shock. A slightly smaller caliber bullet travelling at a higher velocity is a better ticket for lion than a larger caliber bullet travelling at a slower velocity (all other factors being equal).
An interesting field observation of mine regarding the terminal effects of different calibers being used on different big game (which might be of some benefit to you for future hunts) is this:
For body shots on Cape buffalo, a freshly loaded .458 Winchester Magnum (with velocities actually chronographing at the desired 2130 fps or thereabouts with 500Gr bullets) has noticeably more terminal effect than a .375 Holland & Holland Magnum (with velocities actually chronographing at the desired 2530 fps or thereabouts with 300Gr bullets)- Assuming of course, that all other factors are equal.
For body shots on lion, a .375 Holland & Holland Magnum (with velocities actually chronographing at the desired 2530 fps or thereabouts with 300Gr bullets) has noticeably more terminal effect than a freshly loaded .458 Winchester Magnum (with velocities actually chronographing at the desired 2130 fps or thereabouts with 500Gr bullets)- Assuming of course, that all other factors are equal.
But the .458 Lott (with velocities actually chronographing at 2350 fps or thereabouts with 500Gr bullets) is superior to the .375 Holland & Holland Magnum and .458 Winchester Magnum for body shots on both Cape buffalo and lion- Assuming of course, that all other factors are equal (and that the recoil doesn't bother you). Whatever I said about the .458 Lott, also applies to the .450 Rigby Rimless Magnum and the .450 Dakota.
Similarly, for lion hunting... I would personally opt for a .500/416 Nitro Express over a .470 Nitro Express.