I started off my journey in .223 reloading with IMR 4198 which many bench rest shooters seem to swear by. However, my experience with it has been less than pleasant. I worked up several loads with 55-60gr bullets over 19.0-21.5gr of powder. Almost no batch, crimped or not, seated at 2.200" or 2.250" ever properly cycled my AR. Even bullets with cannelures loaded over max(most manuals said 20.5max) and well crimped still had issues. Accuracy was always good to excellent but reliability has been poor. In my mini-14 they all fed and fired flawlessly. I have recently acquired some Varget which I expect much better results from. However, I have heard of people having great success with H335, Win748, AA2230 and 2520(for larger bullets) as well as Varget. We'll see how results come in, but if you have an opinion, let it be heard.