Core metal insert for weatherseals

A core metal insert is provided for reinforcing a weatherseal. The core metal insert has a generally U-channel shaped cross-section and has first and second tines extending from a longitudinally extending backbone strip. The tines are bent to provide the U-channel shaped cross-section. The backbone strip is preferably double-coined to provide first and second grooves, one along each face of the backbone strip. Double coining results in greater length extension of the core metal insert, and also provides for more reliable bending of the tines which are less prone to snap off due to bending stress. Preferably, the backbone strip is provided with a plurality of score marks on both of its opposing faces to facilitate reliable and consistent severance of the backbone strip along the score marks to provide discrete structural staples in the weatherseal.