If I'm thinking about taking a deer with one of them, it no doubt would be with the Mini-30. I know, a lot of people think it's okay to shoot deer with a .223 and I am aware many have fallen to this round but I wouldn't want to shoot one with it.
Count me in as one who thinks "it's okay to shoot deer with a .223."
I started using the round in concert with a stainless Ruger Mini-14 Ranch Rifle the same year that Winchester introduced their 64 grain Power Point load in the caliber. Over the 20 plus years that have passed since then, most of the deer, mouflon sheep, and feral goats that I've killed have been felled with the .223 Remington. All so far have been one-shot drops and most have been DRT (dead right there). Those that haven't been DRT didn't trot more than 25 paces or so before piling up. I can't fathom how any other cartridge would have killed these animals any deader with the same shot placement. Even with the Power Points, most hits resulted in complete pass-through penetration. On a 100 yard double-lung hit, the result is usually a caliber sized entrance wound, frothy pink goo where lung tissue used to be, and a two-times caliber hole going out. My .30-30 would kill the same size game just as dead at the same distance, but it makes a fist sized or larger exit wound.
I was convinced that the .223 was enough cartridge for the deer hunting that I do under the conditions that I do it a long time ago and for me, the argument of whether or not the .223 is a "deer cartridge" was decided in the round's favor two decades ago. The caveat is that most of the deer I kill are small blacktails and similarly sized whitetails and the common feature of the terrain I hunt upon is that none of it lends itself to long range shooting. Virtually all of my shot opportunities come at ranges under 200 yards and most come at less than half of that distance. On small deer at fairly close range, the .223 with proper bullets put in the proper place kills deer just as dead as anything else does.
While I was sold on the cartridge early on, I was not as enthusiastic about the suitability of the Mini-14 in that caliber as a "deer rifle." I believe that the maxium range potential of the cartridge is greater than that of the rifle. The .223 can deliver spectacular kills on smaller varieties of light, thin-skinned game, but it can only do so if the bullets are placed where they need to go in order to get those stellar results. My Mini-14 was only precise enough to insure instant death as a foregone conclusion out to about 100 or 125 yards.
In my hunting, I found the .223 to be entirely adequate but I cannot say the same for the Mini-14. I retired it within a few years of initial deer hunting service and replaced it with a T/C Contender Carbine with a custom 1:9 barrel in .223 as my backpacking blacktail rifle. The .223 Contender Carbine is what I used to kill the majority of the deer (small sub 120 pound blacktails and whitetails) that I've taken.
I tried the Mini-14 as a deer rifle and found it lacking, but the limitations were all in the rifle and not the cartridge it was chambered to.
-JP