Mine weighs about 9 3/4 pounds on my bathroom scale.
It is a 1842 .69 caliber smoothbore.
Some photos of this gun are available in the photo forum, or you can follow this link:
1842 Springfield
Another link to the same gun is here:
Springfield Project
The Dixie Catalog says the powder load for the origianl .69 cal smoothbores was 80 grains of FFg behind a .680 diameter ball.
Dixie later gives some conflicting numbers when talking about velocity. They say the .69 cal smoothbores had a muzzle velocity of 1500 FPS with a 412 grain roundball over 110 grains of powder. This velocity gives 2060 Ft/Lbs of muzzle energy.
They go on to say that the 110 grain charge includes the priming for the pan so the actual charge would be something less although I find it hard to believe the average shooter used 30 grains of powder to prime the pan. This velocity was listed as "Army" information.
It might be noted that my ballistics calculator says a .680 ball weighs 471.7 grains and if fired at 1500 FPS it has a muzzle energy of 2369 Ft/Lb.
The 1842 Springfield was the first Precussion gun issued in quanity to the U.S. Army troops. There had been other precussion guns tried and issued by the Army before this gun was adopted but for the most part, those were on experimental basis.
Being smooth bore guns, these guns were used a great deal not only in the Mexican/American War but in the Civil War where they were often loaded with buck and ball loads.
At close range, these produced devastating results. It is after all the equivalent of a 14 guage shotgun.