Previously, I had mounted a new 507 Competition on a Maple Leaf direct milled G5 19 slide with a Mayhem comp, and experienced malfunctions with it shooting support hand only. The 507 Comp is a relatively large and heavy optic, so I replaced it with a 407CO. This morning, I zeroed the 407CO, then shot it support hand only. It ejected the brass vigorously, shooting with my normal support hand grip. I then decided to shoot it barely holding onto the pistol, support hand only. I was surprised that the brass ejected just as far as when I held the pistol with my normal grip.
Without saying anything, I had my wife repeat this. She started with her regular grip, then with a lighter grip, and finally with a barely holding the gun grip. In each instance, the brass ejected similarly. However, the brass only went about 60 percent of how far my cases ejected. YVK has a theory that the weight of your arm is a factor with a lightweight pistol like a Glock. At least this morning, how firmly you gripped didn't change how far the brass ejected with this particular pistol/optic/comp setup for us.