The Ithaca "bridge trestle" pad was introduced in the 1931/32 Ithaca Gun Co. catalogues. However, the Ithaca "bridge trestle" pad of that era didn't come in a large enough size for the the Magnum stocks. The NID Magnums normally got a seven-slot Jostam Anti-Flinch or a Hawkins with the heart-shaped openings. The Hawkins pad with the heart-shaped opening was introduced about 1925.
You can see in this picture that serial number 500000, the Magnum-Ten made for Chas. Askins the Elder, has a Hawkins pad --
