Printed in Orange PLA v4 has a new bevel at the to for improved compatiblily in more chassis. Magazine/Chamber Block for Bolt action firearms that take AICS Short Action Pattern Magazines Tried and tested in a Tikka T3x in aftermarket chassis that runs AICS SA pattern mags. Some modification may be required for other makes and models. If this is the case I would love feedback and photos, to help improve the design. It is held in place by the magazine catch and simply drops free when you depress the release.