Recently finished a 7" dedicated .22 build and want to add a ~5" 9mm and 10.5" 5.56 upper as options. I've never run a build in either length so I don't have any experience with what type of buffer to use. Basically just looking for if there is buffer will give me the best of both worlds or if i will need to swap with each caliber. Doing some reading it sounds like 9mm buffer will allow the use of both but I'm looking for some input from people with builds around these lengths. I realize a dedicated 9mm lower setup would be the best option and that will probably come down the road, but don't mind swapping around some parts for now.