These are Markll No 4 rifles. With the battle sight being used, they should shoot about 6-8 inches high at 100 yds, not low. I know tis is a silly question, but did you strip the rifles completely to clean out all of the cosmolene? I've helped out a few fellows before with similar problems and its usually been the case of either poor cleaning of cosmolene from the bedding areas or inexperience in takeing off and putting the stock back on.
We did have one problem where the rifle had been cleaned with many kettles of boiling water and the forestock warped, but that was an unusual case. bearhunter