In October 1944 the rim material changed from stainless to the same steel that the helmets were made from (Hadfield Maganese). Evidently, for some unknown reason, at the same time, the weld seam of the rim also migrated to the rear.
Note: I personally have found numerous rear seam WWII era shells with stainless steel rims, suggesting the existing stocks of stainless rims must have been used up even after the change was put in place
thanks guys I,ve just had quick search and found this quote from top pots site.
Rod
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