Yes I was demonstrating shot placement on say elephant by our great African hunters. The 303 had a power around 2500 ft lbs , prior to that it was 8 & 4 bore. There’s a clip on utube shooting an elephant shot with a 4 bore a slow death for the elephant with poor body shots My 450-400 unmentionable double , steel jacketed dangerous game bullets , great for Africa 4125 ft lbs of energy great for elephant head shots and cape buffI don’t know about this…the .303 is early modern smokeless, it’s ballistically a different beast than a .40 calibre muzzleloader. I don’t think it’s realistic to make direct comparisons.
I’m sorry to hear about the state of things in Great Britain…seems that even though they separated from the EU, still couldn’t help going Woke.
With a BP .400 you might just get up to 2000 ft lbs but probably more like 1400 ftlbs To get to 3700 ft lbs you woul need to go up to like a .6 bore like my .623 bore cape rifle made for African farmers
So all in all thinking would I go up against a bear with a muzzle loading .400 many did I guess and many the bear won
Even .5 BP cartridge doubles , I have one, only produce 2800 ft lbs of energy , my ..36 ML double only produces 900 ft lbs So I recon for bear or elk I would go for a .5 plus every time. For my wife a .4 would be great for rabbits squirrels and the odd deer
Just buy what makes You happy. I have 23 guns still not happy. Ha ha ha
It’s interesting rambling along with thoughts on say 1775 hunting still applies today
Great to chat and challenge our thoughts Love from
Me and Joan , London
Ps Joan hated guns. Tough