There was a chap in the US who advertised in Man At Arms magazine for whaling guns and related items.
The museum in Iqaluit has a mounted type of muzzleloading gun that was recovered near the mouth of Frobisher Bay. The brass aiming bar along the top is marked "ACTIVE DUNDEE" with a couple of dates, late 1860s, early 1870s. Active was a well documented Scottish whaling ship. The gun was loaded with an explosive bomb lance when recovered. Basically an iron tube originally filled with a bursting charge; a piece of fuse would be ignited by the propelling charge. The fuse would burn through and cause the bomb to burst after penetrating the whale. The gun is 30-odd inches long. The Scottish whalers operated out of Peterhead and Dundee. American whalers out of New England, New Bedford, etc. If you want some interesting reading, get a copy of Arctic Whalers, Icey Seas.
Referring to guns described in links in the website above, Pierce type guns were, and perhaps still are, in use. Two are in museums in Skagway and Fairbanks, AK. One of these has a burst barrel. These guns tip open like a shotgun, the barrel being held closed by a sliding plate activated by a lever on the breech. A separate lever cocks an internal hammer, which strikes a firing pin, firing the propelling blank cartridge. Modern reproductions of this gun have been (are being) used by Alaskans and by Eastern Arctic Inuit. The modern guns were made by The Naval Company in Philadelphia, a marine machine shop. Primarily all brass and bronze construction, 8ga smoothbore, about 25 pounds. The bomb lance fired is about 14" long, and uses an inertial cylindrical hammer to fire a percussion cap which ignites a length of fuse. Another device is a gun mounted on the end of a lance shaft. Fires the same projectile with the same blank cartridge. The trigger for this one is a long rod. Rod contacts whale, bomb is fired at point blank range. These guns have been used in the last 20 years to take bowhead whales in the Eastern Arctic. The lance gun was rebarreled with a stainless steel barrel bored to accept modern, safe to use Norwegian grenades. The 19th century guns and their ammunition are dangerous to the user. The bombs are activated by the inertial hammer when launched; the hammer is kept in lace literally by a toothpick. Bang the bomb on its tail, or drop the loaded gun on its butt and the bomb is activated and will burst in a few seconds. The guns and their projectiles are basically home made grenade launchers.
Modern whaling uses a deck mounted 66mm gun.
I had a peripheral involvement with the first modern whale hunt in the Eastern Arctic. I prepared the launching blanks and grenades which were used.
Here is a photo I found on the 'net. Cannot tell from the photo if this gun and its bomb lance is 19th century or modern, but that is what the gun and bomb I worked on look like. In addition to preparing the bombs, I replaced the mainspring in the gun to eliminate misfires.
