Why did octagon barrels die out?

Octagonal barrels were fine when they were filed down by hand, and the labor costs weren't too great. When turning on a lathe became cheaper, the octagons held on among old-timers for a while, but at a price disadvantage, and they went away.

I don't care for a lot of weight, but I too like having the weight a little forward in a rifle.

Some manufacturers are offering octagonal barrels for Cowboy Action Shooting, go look on Marlin's website.

Cost and popularity are the primary reasons that so few are made anymore. Rifles like the Savage 99 and the Mausers and Enfields led to a change in peoples tastes.

Those old barrels where heavy and steel and machining was pretty crude....back then. A smooth round...tapered barrel out of stainless or quality steel makes a great gun these days.....and key is weight. Ever try to hold up one of those old muzzle loaders with thick octagon barrels????? Heavy. The new Remington as you know has a new barrel out that is triangle shaped that works better for accuracy,vibration,strength,cooling,stiffness....etc....

I'm with you when you say you like the old Octagonal barrels. I love them because they are easier to slot and mill rails on (scope on muzzleloaders... I know, I know it's a travesty...). They were heavy, and usually more expensive as compared to round barrels, as others have stated. I like the fact that a octagonal barrel is more rigid (here's where I sound loony...), therefore keeping the barrel straighter as the bullet you fired travels down the barrel (resists harmonic vibration/distortion). Doesn't hurt that they look nice too... I don't know why they phased them out, I personally like the look of them.

Cylinders were easier and cheaper to mass produce.

New machining techniques now make Triangular just as cheap to produce.