Hopefully I can explain this in some sort of sense
They have minimum calibre laws for hunting. Here in VIC 130gr .270 diameter bullet or larger for Sambar. I've put some numbers into the JBM ballistics calculator and get this which is where I start to wonder.
Picking the lightest .270 load with a 130gr bullet from the ADI website I get this.
Muzzle velocity 2,720.
Energy at 100m 1,730 ft-lbs.
Energy at 200m 1,330 ft-lbs.
If I put in the details for a max .243 load with a 105gr pill I get this.
Muzzle velocity 3,000
Energy at 100m 1,830 ft-lbs.
Energy at 200m 1,600 ft-lbs.
(I've rounded a few numbers to make it neater but that's about right, only 5-6 here or there.)
The Gov says the top load is fine, but the bottom load is illegal for hunting Sambar.
On paper though it looks better? I could have a .243 and do everything going by that.
So why couldn't I use a .243 after looking at those numbers?
Does that not come across in practice? Does a lighter bullet not do the right job even if it hits with more energy?
Help a noob understand