I have been loading 223 rounds for my contender pistol in a small base die for nearly twenty years.
You may lose a little brass life but I dont think that this has happened to me.
There are two schools of thought about sizing for accuracy. The well known one is to size as little as possible. The other is to use small base dies to obtain absolute uniformity. If you lose any accuracy is should be such a small amount that you wouldnt notice it. Enjoy your new barrel!
Elwood