Anything thing to think about is that the McGill chin up is trying to work scapular retraction. Brian pulls explosively and he knows what he’s doing already, but if you feel like you’re defaulting to using your arms to initiate the pull, you may be skipping the back work you’re supposed to be getting. When Brian first showed me the McGill pull-up he had me hang, then pull only with my back and shoulder blades to get them back and tight (it’s almost the reverse of a shrug), and then pull up from there. Give it a go and if you do it right your back will be on fire. If you don’t feel your back still just slow the movement down and teach the muscles to engage.