IMHO - It is possible and quite intriguing that 'Marksc' may have a Krag receiver, that was made purposely, for use on one of the Watervliet type sub-caliber artillery training devices.

Attached is a photo of one such device that was excavated on Bannerman's Island (in the Hudson River far north of NYC).

Unfortunately, none of the pictures I can find of the Watervliet sub-caliber artillery devices show the left-side of the receiver.

It seems clear to me that the Krags, used with the artillery sub-caliber devices, had conventional triggers.

That Linkage Mechanism, in the picture supplied by 'Local Boy', is actuated by a small rod joined to the Cocking-Piece. It is not a 'triggering' mechanism. It is designed to pull a small cable a short distance.

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