You will not need to run a LA on a SAUM. You will never need to load that long so yes it's a waste of space. If you dropped down to a medium or short action, not only will you have the mag length, but also save weight on your build. Depending on what your original build was a good muzzle break, or suppressor, will make all the difference in the world on higher case capacity cartridges. In most cases bringing overall recoil, and faster follow up shots possible in larger casings. Good luck and enjoy the I have no idea what to build dilemma….
I say that because I never know for myself. It's truly a disease, worse than Alzheimer's, or HIV, like the black hole of space you will never fill the void. Once you start you just pray you can maintain. You start to think maybe I can build a new "better" rifle…. You troll the internet trying to find the new flavor of the month . You think to yourself if I sell the wife, maybe the kids, maybe the house… No one can save you. Then you think maybe rehab! There is no rehab there is no THERE CAN BE ONLY ONE! No matter how many times you watched Highlander. It's all a lie!!!
Then you choose a rifle caliber, action, stock, trigger, brass, powder , primers, color…. And you think you have it. Then you see a guy shooting elephants at 4.1 miles with a creedmoor. And all is lost… truly heartbreaking. Wish you the best of luck, and happy holidays.