There are integrally suppressed AR uppers in 5.56 and 300, for sure. Some stuff in 9mm and 45acp as well. These days, I’m not sure they work any better than a detachable suppressor, due to core/baffle designs coming on. You can save some barrel length, for sure. However, if you’re running subs, you don’t need nearly as much barrel to begin with and your range is cut down, so match accuracy isn’t often a huge concern.