I understand you would have more shot because of the 7 1/2 shot but it is also a lot lighter shot . Are you saying the 7 1/2 will kill as well as the 5 shot or that you just have a tighter pattern . If the 7 1/2 will work then why not just use all 7 1/2 shot . I don' t see what you would gain other than a tighter pattern .