Found this interesting description about another Belgian Double Barrel pistol, almost identical to mine.
Thanks to UNPROFOR1994 for finding the source.


"2 SHOTS WILL DO: South America, especially Brazil, Argentinaicon and Uruguay, was the destination of most 2-barrel pistols made in Europe in the second half of the 19th Century. There is not much written about these unique pistols that were manufactured for both center-fire and pinfire cartridges. Evidently the previous 2-barrel flintlock and 2-barrel percussion pistols were so appreciated by small arms users, that when the new metallic cartridges appeared folks just kept asking for two-barreled pieces (“two shots will do, thank you”). There is no doubt that the only large market in the world for these odd pistols was South America. Even the widespread use of the mainstay 6-shooters and the later semi-auto pistols didn’t persuade an important minority of gun-owners to move over to the more modern contraptions until well into the 20th century. A few years ago we sold a top-break, center-fire, two-barreled pistol (a shorter version of this one) that the owner had used right up into 2005 for shooting carpinchos (basically 50 pound rats) using the .450 Adams cartridge - of course, over several decades he had had to use .45 Long Colt brass cut down to .450 length.

THIS PISTOL, SPECS AND CONDITION: The barrels measure 7-7/16 inches (190mm), and the pistol’s overall length is 11-1/2 inches (318mm). For size comparison we have shown it with a Smith & Wesson 1st Model DA Revolver in .44 Russianicon – NOTE: the S&W is not for sale with this auction. Both actions work well with a half-cock safety position, and there is a separate safety mechanism between the hammers; when this safety mechanism is moved forward (only when the hammers are in the half-cock position) it is impossible to fire the gun. Lock up is fairly tight with a bit of movement of the barrel assembly. The top-break mechanism works well. The extractor functions as designed. There is good rifling with a few light to moderate pits especially towards the front of the two bores. The original nickel is about 40% with areas of rust but no noticeable pitting. The original walnut grips are in good condition showing the entire diamond pattern on the grip area and a carved section at the top on each side.

MARKS AND STAMPS: On the action at the rear of the barrels: 450. On the left frame under the grip: B. On the bottom of the barrels: crown over R (1894 rifled bore punch), star over O (this must be an 1877 Inspector’s mark, but it is not on any list we know), the “Little Tower” 1853 Inspection punch, star over B (1877 Inspector’s mark, note: there is a letter L stamped beside both of these punches, it appears to be added later and we do not know its significance), the 1852 Black Powder mark, the post-1894 Liege proof.

THE .450 ADAMS CARTRIDGE: The .450, also known as the .450 Revolver or the .450 Colt, is a cartridge that was originally used in converted percussion Beaumont-Adams revolvers in the early 1870s. It became the Britishicon Army’s first centerfire round. It carried a 225 grain bullet and developed a velocity of about 650 fps. It was similar in ballistics to the .44 Russian cartridge. The .450 was the forerunner of the .455 Webley cartridge, and it was in use in South America right up into the 20th century. All .450 handguns can shoot reloads made from cut-down cases of the 45 Long Colt or the British .455. Fiocchi occasionally produces a run of the .450 cartridge, although they do not seem to be available right now:

CAN THIS PISTOL BE FIRED? This pistol carries the 1894 Liege proof on the bottom of the barrels; the Liege proof was the absolute best proof in Europe in the 19th century. Several small arms manufacturers from Great Britain and France, especially, sent their finished guns to Belgiumicon just for this proof. Each chamber had to be proofed or proved by firing four shots with a double load. No junk ever got past that proof. If a Liege-proofed gun is in good mechanical condition it can usually be fired today with the black powder loads for which it was designed. Of course we recommend that you get this pistol examined by a certified gunsmith before ever firing it."
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