The long for weight Barnes 62 and 70 grain TSX and TTSX .224" bullets work very well in .223/5.56 for whitetail deer. They are solid copper, expand rapidly, but retain virtually all their weight. Break bone when encountering it, and still leave an exit wound. With proper shot placement it is usually dead right there. If they do run, it won't be far and the exit wound leaves a blood trail.
You need a 1:8 twist barrel to shoot the 70 grain, but can shoot the 62 from 1:9. As with any small case capacity hunting round, keep use to 150 yards, max, as retained energy drops fast after that.
So sad about Remington bailing on the very promising 30 AR. I have 6mm Rem. and .280 Rem rifles in my collection. I still hunt with them. The 6mm is superior to .243 Win, and the .280 is superior to .270 Win or 7mm-'08, but Remington screwed up the marketing on those too. Each has lingered but are virtually unknown for new rifles, now. Fortunately, for us handloaders, cases are available, bullet options plentiful, and we can take advantage of their better performance.
Try those Barnes bullets in your .223/5.56. Barnes even has "hot" 5.56 pressure load data for them. H-4895 works well with either and accuracy is superb, approaching match grade from a good barrel with appropriate twist.