So far from what I have seen powder supply is not what is hard to come by. Even in the last shortage powder was easy to come by. Primers are another story altogether. I also advise practice with the same load you compete with.
H-335 is a good one for 55 grain bullets is my go to. It is standad among many that compete with 55 grain bullets for a reason.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.