Nice shooting and write-up.
Can't help you with the suppressor, or the hot weather coming soon, but I would load up a box of 50 rounds and go 10 rds of 24.0grs, 10 rds of 24.2grs, 15 rds of 24.4grs and 15 rds of 24.6grs, shooting 5 shot groups at 100yds to see what you see.
Or any variation of...