The last deer I successfully tagged was a 120# Florida doe shot at approximately 60 yards. The gun was a Ruger Mini-14 Ranch Rifle. The bullet was a handloaded Hornady 55 gr. Spire Point w/cannelure. At the time I recall reading all sorts of 'horror stories' regarding the high velocity .223 rounds 'blowing up' on the surface and not reaching the vitals of a deer. I took great pains to select a 'toughly constructed' bullet. At the time the only 'real' choices were the selected Hornady and the new Barnes 64 gr. SP. Unfortunately, the Barnes bullet and my Mini-14 weren't compatable.
The bullet entered the right shouldered shattering it, penetrated the heart and both lungs, penetrated the left shoulder and lodged perfectly mushroomed under the hide. The doe ran 30 feet and dropped.
Fast forward a few years. The rifle is now a Bushmaster E15A2 HBAR with a 1/9 twist, but I am not presently set up to handload. A lot of work has been done on .223 bullets since 1986, as well as R&D work on the .223 Remington round itself. I know Winchester loads a 64 gr. SP designed specifically for the smaller Texas deer. However, I haven't read any 'success stories' written about it.
I also haven't read anything about the Hornady 75 gr. bullets or the solid copper bullets from Barnes. On deer UNDER 200#, how are these working?