Calibre conversion on SAKO TRG M10 is done through a calibre change kit consisting of a barrel, complete bolt and a magazine. Head space of each TRG M10 barrel assembly is set to minimum tolerance and barrel assembly is proof fired with over pressure loads at the factory before shipping to customer, therefore the use of gauges or other measuring devices is unnecessary upon barrel change. The bolt is always supplied as a complete assembly in the calibre change kit. This ensures that the operator does not have to disassemble any part of the weapon while performing conversion, thus minimizing risk of losing or mixing up critical parts.