I can't say I agree with everything you said there and don't want to start an arguement, but someone (with a metallurgical background) once pointed out to me that it takes significantly more force to stretch the brass case than blow it outwards. (It was in response to me thinking that the force of the reloading expander ball in a resize die contributed to case lengthening).

While minimising brass sizing operations will help with brass life - I'm not sure that the shoulder formed on the 22Hornet and Bee variants is actually doing all that much, unless it is a sharp and largish shoulder and the headspace on the rim is excessive, or rather if the rim headspace is good then shoulder positiion isn't going to make any significant difference.

I agree 303's can have good case life but only if the headspace on the rim is correct. You won't be able to set up effective shoulder headspacing on the standard 303 case because the shoulder is too weak and the case will head separate after a relatively low number of reloads.

I guess what I'm saying is that if Perry's rifle headspaces correctly on the rim then what he did to firearm was totally adequate and should not affect case life wrt head separation. It also means that if his headspace is out then he won't be able to effectively use shoulder headspace on this cartridge.