The seeming stock 'repairs' are not repairs!
In order to make this construction possible, each single one of the four rear barrels had to be inserted in a square block of wood, which then was glued to a cutout recess in the buttstock. It is not possible to do this any other way.
The very same procedure was used on my four barrel mace of ca. 1540: all barrels are individually inset and surrounded by pieces of wood:
http://www.vikingsword.com/vb/showth...hlight=meyrick
Best,
Michael