HI John,,,,the Gibbs version still uses a 30-06 parent case,,,no matter what the taper is ,,,it has to start with the base line and it is smaller than .308,,,,,you can do it ,,,but it will be a cobbled up mess that will give you ctgs that are hard to load,,(they are wayyy bigger than the die and you will be jumpin up -n-down on the handle,,)and case life will be short,,,,guys do things like this every day and have problems and cant figger out why,,,,,you see lots of non-wildcat chambers cut with reamers that are too big at the back causing primer pockets to go away prematurely,,,,there is a thread on here now about a 308 Palma rifle being fired with mild loads and the primer pockets going away,,,and they are blaming the primers,,,,hahaha,,,,Roger