It's just a T3X/T3 action and the only difference is the barrel diameter and the mag system in the stock that the action is sat in when marketed new. The action will sit in anything T3/T3X and calibre/cartridge doesn't matter, it's one size unless you go for chassis's, which generally go short or long in description and this is only due to the magazine system.. to take general AICS type mags that come in specific sizes etc. However with regular stocks and bottom metal, that's not an issue anyway.