Traditions also sold a very similar model with a full octagon barrel that was called a Pioneer Rifle.
K-Mart sold them for $179.00 before they went bankrupt.
I noticed that model pictured not only has a round barrel but also a patent breech instead of the drum that the Pioneer Rifle had.
The [schnable] fore end on this model is fairly slender and the round barrel channel would leave more wood for a stronger fore end compared to a full octagon barrel channel.
Plus the round barrel would probably weigh less than a similar full octagon since some of the metal has been lathed away.
The octagon breech would probably leave more metal for threading the breechplug. Plus the octagon section may also also add some stability and support to the barrel. The transitional octagon to round barrel is a traditional design of black powder long guns. However the octagon section of this barrel is fairly short when compared to the more traditional long guns.
The transitional octagon to round part of the barrel usually has what are called "wedding bands" which are rounded decorative rings that mark the transition. The barrel pictured doesn't have those probably because they're more expensive to lath and would add to the cost.
The Pioneer had a 28" barrel. How long is the barrel on this Trophy rifle?