A dedicated upper with the correct twist is the best way to go. That said it does require purchase of an additional sighting system if you're not using iron sights. For occasional plinking use the CMMG unit works fine for me. I also use the CMMG unit if I have more than one person shooting. I have and use both.
You'd probably be satisfied with the accuracy. ARs in 223 are available with different twists. If you is 9 to 1 you're probably better off than with 7 to 1.![]()
The CMMG units run $200 or so as I recall and a new upper would be double that or more I think.
I use a dedicated upper from CMMG. It shoots well, but there are a few things I don't like, such as the last shot bolt hold open only works when a magazine is in the gun. When you drop the empty magazine, the bolt goes forward, so you have to pull back on the charging handle when you insert a new magazine. But the operation of the bolt and feeding works really well.