Yeah me too as other brothers have stated. What I do is to open my straps as open as possible then pull them for a secure fit over my shoulder bells. My ammo pouch is attached to my left shoulder strap. Put your pauldron after this. And under your black under suit put some shoulder sponge cushion so it takes the direct weight from the pack and the shoulder bells.
One final tip: Stretch your neck, back, arms up to 5 mins before gearing up. That way the pack doesn't kill you, only the killer looks people give when they awe at you 😄