When your Smith was made, the 12-gauge 3-inch progressive burning smokeless powder, high velocity load, Western Super-X or Peters High-Velocity, carried a payload of 1 3/8-ounce of shot.

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The 12-gauge 3-inch Magnum load with a 1 5/8-ounce payload was introduced by Winchester and Western in 1935 along with the Winchester Model 12 Heavy Duck made for 12-gauge 3-inch shells. The 12-gauge 3-inch Magnum load with 1 7/8-ounce of shot was introduced in the late 1950s. In later years I've seen 12-gauge 3-inch shells with as much a 2 1/4-ounce of lead shot.

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Pressures aren't the issue, they are all within SAAMI specs. The issue is the damage the recoil forces of these heavy high velocity loads can do to your already too fragile, 100-year-old, L.C. Smith wood.