Harry, which spring did you use in your .177? Did you buy a Gunparts 350? If so, did it come with a set of inserts for the globe? I'm curious if Diana has been including them. My 340 from AoA came only with the post.
From what I recall, Diana used to throw in the full set of inserts. I'm guessing the globe takes the same size as the HW. I have older Norica's with their globe and that one is a skosh smaller.
You'll be wanting to shoot the heavier pellets in that puppy. Those 6.48gr pills will be slamming the piston. Too light to create enough inertia to cushion it. I don't know why companies that know better even bother testing with them. Unless they like to sell more guns. Hope you enjoy your new gun. I'm still pondering one.