Tony's rifle above is the lightes made 9.3X74R S/S double on the market today, and it handles the pressure of the 9.3X74R fine, and is a very well ballanced, and accurate rifle!

I have a 9.3X74R Merkel S/S double rifle that weighs in at 8.3 pounds, which is a little heavier than the Chapuis. The measurements for it are as follows:

Distance between the fireing pins is center of bore, to center of bore 1.04", and the outside measurment of the BOTH barrels at the breech is:2.105", with a chamber wall thickness of:.289

barrel dia @ 2.7" is .822"

barrel dia @ 6" is: .760"

Barrel dia @ 8" is: .629"

barrel dia @ 10" is: .595"

barrel dia @ 12" is: .567"

barrel dia @ 14" is: .549"

Barrel dia @ 16" is: .537"

Barrel dia @ 18" is: .529"

Barrel dia @ 20" to muzzle is: .5265

Barrels are 23.6"

I'd say My rifle is most likely the 20ga in size of action, because I know you can get a pair of 20ga barrels for it, and a set of cape gun barrels with 20ga shot, and the full range of rifle chamberings up to 9.3X74R for this rifle. I say, as well the size comparison for the Chapuis would be closer to the 28 ga size. A very trim little rifle, that is well made, and finished, as well as being super accurate!