I'm not sure the weight is reduced significantly. I was always told that the gun looks better swamped.

What is a "swamped barrel"? I don't think my old Renegade falls in this category.

I might add to 700 nitro's description that the "waist" of the hour glass occurs much closer to the muzzle than the breech. In my 42" flinter, the narrowest spot is roughly 9" back of the muzzle.

Once you have a long swamp barreled rifle, you will never be completely satisfied with anything tapered or straight again.

Brent

I have built smokepoles with and w/o swamped barrels. It removes about a pound from the muzzle and that is a lot if you are shooting one all day in competition or toting it around the woods all day. The swamped barrel seems to help balance a lot when holding on target putting more weight closer to you body and rifle holding hand. I have shot them for 30 years, sometimes for three or four days solid in competition and that is where the swamped barrel shines.
It is also cool looking. Most people never notice it. They just look at the rifle and say, I have one of those new in-lines for hunting. I say, Yeh, they are nice.
It was said earlier, the best way to describe the barrel is if it was out of the stock, it would look like an hour glass.
Mike