Originally Posted by shocking300
I chronoed the loads minutes apart. Let me know how the volume measures up. Thanks
I just measured the capacity of the Winchester and Norma, new, unfurled cases using Retumbo powder filled to the mouth. The Norma case is 88.3gr, the Winchester is 83.4gr. The Norma holds 4.9 gr more powder. This is likely where your velocity went. As mentioned, the Norma case is dimensionally fatter.