The two iron cannons near the magazine at Fort McHenry, in the foreground are (front) a 4-pounder gun and (rear) a 6-pounder gun. Their lines are very similar to the bronze 6-pounder we're researching.

In fact the lengths of the various sections of the 4-pounder are the almost exactly the same as those of the "SNY" bronze 6-pounder. The external tube diameters measured on the iron 4-pounder pictured are slightly larger than those of the "SNY" 6-pounder, presumably to account for the fact that cast iron is not as strong as bronze.

I'd suggest that these two iron guns were cast by the same foundry that cast the "SNY" 6-pounder, since the lines and proportions are almost identical.

This is a significant finding in our search to identify the founder of the SNY gun. The reason is that not all founders cast both iron and bronze. In fact, most seemed to specialize in only one metal. One familiar example is Paul Revere who cast only bronze cannons. I haven't checked exhaustively but this new fact may also eliminate James Byers of Springfield MA., who as far as I have found, only cast cannons in bronze. The list of possible founders is getting very short. We're now looking for founders who cast both iron and bronze cannons.