Re: Small base sizing 223 die question.
Reloading section would be better for this.
Small base is only neccesary if you need them, its more about feeding and reliability than accuracy.
My AR and two others I shoot with (Model 1, Bushmaster, and RRA) have functioned 100% reliably with just a regular FL sizing, with Redding and/or Hornady dies.
The downside to small base is if your chamber is not tight, you work the brass more than neccesary, effort required is greater, and you're chances of sticking brass may be increased.