I've always shot a 20 gauge hunting deer in my state land shotgun state of CT.
I started out shooting 2.75 inchRotweil Brenneke Magnum rifled slugsout ofa smoothbore, andthey do make larger wound channels and exit wounds than the saboted slugs do that I shoot out ofa rifled barrel now.
Since I stockedup on thesesabotslugs, I haven't switched to any "premium" ammo. So Ijust shoot standard 2.75 inch WinchesterBRIsaboted lead slugsthathavethe original BRIhour glass shape. They start out at .40 caliber and the only one thatI ever recovered from a deerexpanded to about .64 caliber. It had traveleddiagonally throughmost of the length of alargedeerfrom a frontal quartering shot, and I recovered it fromunder the far hide. The deer ran between 100 - 150 yardsafter being shot from pretty close range basicallybecause there wasn't an exit wound and it was the largest deer that I've shot withthe BRI sabot. So it ran twice as far as normal.But there was still enough of a blood trail to lead me towhere it was foundalreadydead.
I've neverlost a deer, but they do run a little ways if they aren't hit in theheart orbackbone.But I have the utmost confidence in using a 20 gauge.IMO the 20 ga. sabots arenotthe sameas using a 12 gauge, but thena 12 gauge is not as comfortable for meto shoot becauseit has noticiably more recoil and muzzle blast. The 20gaugeworks fineformostevery deer hunting situation, and I'msatisfiedwith theperformance of the standard Winchester BRI sabots.The last deer that Ishotwent rightdown on the spotdue tohitting the heart. So being able to hit where you're aiming is what's most important.