1) Having a backpack in a deathbox makes the armor swap 1 slot lower, which puts it slightly above the evo damage indicator. You will likely expect people to have backpacks by mid/late game, so be prepared to swap in that exact position. Very early game when people don’t have backpacks, be prepared to swap in the position without a backpack.
2) Some stretch resolutions such as the one I play (1440 x 1080) change the HUD and appearance of where the armor swap is located. Be prepared to know exactly where the armor swap slot is for your specific stretch res.
3) Turn off the “Taking damage closes deathbox or crafting menu” setting. This can really screw you over if you are trying to get a clutch armor swap while getting shot at.
Good luck, and I hope this helps.