I noticed several messages on .223 deer loadswhen I was last paging through the board. Just a quick note from my experience FWIW...

Several years ago, I bought a Remington 700 in .223 very cheap. A fellow had built up a rifle around a used action, using a 26" medium weight shilen barrel with a relatively cheap stock. He "couldn't get it to shoot straight" and I picked it up for about the price of a decent action. Anyhow, I was fortunate enough to know someone who could properly bed the action and barrel; that, plus a truing-up of the action and a proper barrel break-in, and it was shooting up a storm.

Anyhow, last year I had the chance to do some hunting in Texas with one of my father's friends, and the only rifle I had in useful shape was this one. Problem: 1 in 12" twist. While it shot brilliantly with lighter bullets, the 64 gr PP (which I understand to be quite a good deer round) turned in a sloppy 2.5-3 MOA, which was 5-6 times what the rifle could do. (Not Winchester's fault, of course -- just not stable enough.) A friend suggested Barnes bullets, so I bought 100 of the 53 gr XLC (NOT cheap), and pumped it up as hot as it would go from this barrel. My understanding is that rifles can be quite finicky with the Barnes slugs (especially the coated ones), but this one was right in the groove, averaging just under 0.6 MOA.

I took two deer under my tags and two more under tags of others in the party. While 4 animals certainly doesn't make a statistical data base, I can say without a doubt the bullets performed very well for me.

All kills were one shot to the pericardial volume, with no animal moving more than 25 yds; one fell right over. Ranges were from about 70 to just under 150 yards. I recovered two of the four bullets, with both of them pretty much intact and peeled back in the intended "x-bullet" shape (one petal missing from both). The bullet path was not what I was used to in a lightweight .223: deep penetration, and a consistent ~0.5-1 inch channel just plain chewed out.

Under the circumstances (stand shooting with a solid hold, extremely accurate rifle, good conditions, stationary game, etc.), I suppose you could have done the same with a 22 Magnum. Just the same, the perfromance of the bullet bespoke a potential to do well even under less-than-ideal conditions, if you are stuck using something lighter than what you might otherwise prefer.

(Note -- I'm not related to or otherwise involved in any way with the Barnes people. Their product worked really well for me.)

One of the largest Russian boars I ever killed was with a 22br loaded with  a 52gr.bench bullet.  Not a good combo for a tough hog, but the shot was an easy 100 yds. and I knew the bullet would work in the lung area.  Anywhere else would have resulted in a wounded animal.  The only people I know that I would recommend a 223 for deer are already knowledgable enough to make their own decision. For most deer hunters I would say the 223 needs to be left at home.  just my $.02  

If you still have the recovered bullets, I'd love to see a few photos.

Winchester also has a load that uses a 60gr nosler partition(now that I think about it it might be a grand slam). Don't know if that will work with a 1/12twist though.

How about going and getting a 8mm Muaser, I see them in stores for around $60, great deer gun and cheap too.

Curious, glad to see you had good luck with your .223 on Texas deer. I've had great success with the Winchester 64 grns, but your load with the 53 grn. Barnes sounds pretty darn good. I know alot of people believe the little bullets will explode on impact, but I have found good mushroomed bullets in several of my deer also.
Your ranges of kill are almost exactly the same as mine with similar results. Over the next couple of weeks I will test my rig on a deer out to 200 yds. I expect the same clean kills.
My good friend's daughter killed a big buck in South Texas last weekend with her .223 that scored over 165 B&C.  She is winning several of those big buck contest in the youth division. Most people have no idea how efficient the .223 is on deer.  Good luck...