I got a boat load of cannons ( no kidding) not one has a manufactures mark or patent No# . the iron stuff will rust over night and in 50 years will look incredibly old and be very unsafe. I have 3 new cannon in Cast Iron (Sleeved) they are of course my biggest guns .
Everything else is either Brass ., Bronze or Stainless because it will outlast the iron (The Bronze is cool)).
DO NOT BE DISCOURAGED Stay the course megabyte . There is alot to learn in this forum and we all joke and are light hearted however the info gained and shared is 2nd to none and the people here are experts actually . There are many Machinists ., Artillerysts and a combo of the both in these forums., welcome aboard. Lance did answer your question., in which case you came to the right place.
There is nothing wrong with that little cannon it will work for a great signal gun so long as the bore is inspected and in good condition. And with that., its a good start to your collection., Time to get another ., then another ., its a great hobby and a lot of fun., it will live on and on after we are gone.