Hi there, Has anyone bought and put an ACZ ultra stock from Sure-Shot Airguns on to a AA S400. I've got an AA S400 F with the lightweight stock and as a newbie I thought it was a good choice. I'm sure it is, but I'm quickly working out that a bit of weight makes a difference. So, here I am looking at the options. MPR stock? Can I find one? or the ACZ ultra Sure-Shot? Any comments?