Absolutely correct.

A heavier gun does not necessarily mean stronger in terms of its ability to handle breech pressure. THAT is dependent on materials of construction, design of the breech, heat treatment, etc, not merely the sum weight of all the parts.

One of the better examples of this, albeit not a double, is the old 1876 Winchester. Many of these guns were very heavy, and the action certainly is, but it is not a strong action by any definition.