My first LR hunting rig is a custom 7mm Rem Mag that was purpose built to shoot 180gr bullets fast.
Downside is that with a 24" barrel, and a 9" suppressor...scoped, with a mag and ammo, it came in at a portly 22lbs.
I was a young, strapped, college athlete in his mid-late 30s and had no issue packing it as far as I needed to, especially considering it was shot prone off a bipod 100% of it's life.
Fast forward 15 years, I've had upwards of 10 custom rifles in a MULTITUDE of different sizes, shapes, calibers, lengths etc etc etc.
The one I'll be taking this season is an 18" Carbon Fiber 6.5 PRC in a Q Side Chick chassis that will probably come in around 7-8lbs scoped. ALL of my hunting rifles are 18" and in the future, I'll probably do a couple at 17".
Last year I took my west river mule deer at 550 yds with an 18" 6mm Creed and 108 factory ammo.
With the 18" 6.5 PRC and 150gr ammo, I wouldn't have any issue taking shots at 800 yds...but I shoot competitively and do it quite often.
Your skill set will ultimately determine your lethality. Not your weapon system.
For ME, 4-6" of barrel length has absolutely NO baring on my effective range, regardless of cartridge.