The Iver Johnson Hercules had quite an evolutionary run. It began with the W.H. Davenport Arms Co. with their mono-block barrel gun with sideplates --

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

When W.H. Davenport folded up the remains went to Hopkins & Allen and the sideplate double with mono-bloc barrels became the Hopkins & Allen No. 110 --

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

When H & A folded up, Iver Johnson picked up the gun --

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[Linked Image from i.imgur.com]

By 1919 Iver Johnson got rid of the sideplates but still had the mono-bloc barrels --

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

Between 1921 and 24 Iver Johnson dropped the mono-bloc barrels and went to chopper-lump barrels.

The rib extension that does the bolting on the Hercules is only about half the size the Lefever Nitro Special rib extension.