No it is not!
Your wonderful Colt Army is actually chambered for the Winchester 32-20 cartridge.
The 32-20 is a actually a cartridge designed for The Winchester 1873, and the Winchester 1892.
The standard pressure 100gr load is safe to fire in Your Wonderful Colt.
32-20 ammunition is still available, and is a very viable cartridge for self protection.
Have the weapon checked by a Qualified Gunsmith, for wear, and continued use.
Then just enjoy Your Prized Possession!