Please keep in mind, that despite the weight drop to 80 grains, the minimum muzzle energy for large deer is still relatively high.
View attachment 335725
Someone has kocked up here, as to get an 80 grain bullet to surpass the minimum muzzle energy, you'll need the bullets to be going along at a fair clip.
Shame this was not looked over properly, as testing was done by Precision Rifle Services to highlight the issue:
https://www.nature.scot/doc/natures...bullet-weight-lawful-culling-all-deer-species
(Note, the rifle used in testing had a 21 and 3/4" barrel)
A longer barrel (24"+) may help, but I'd be surprised if many/any shops are going to remind people that some factory ammo will fail to reach this requirement with the average barrel being around 20" or so.
Your best best is still going with a heavier (90-100 grain bullet), which will probably require a faster than average twist rate, especially if copper is going to be used.
Some figures:
Hornady 243 80grain CX (copper bullet), factory loaded as 'Outfitter':
View attachment 335728
80 grain bullet will need to be around the 3,150 fps muzzle velocity mark to make the minimum muzzle energy:
View attachment 335729
100 grain bullet will still need to be doing 2,800 fps+ to be legal:
View attachment 335730
Something to keep in mind...