mykeal,
Sorry about the pejorative language. When you responded without any data my troll-o-meter went off. I'm curious to see where our basic differences arise. I'll make some observations and you can send up a flare when you don't agree, okay?
Our area of concern is how the loads are resolved in a open top Colt F-model compared to a closed top model, in this case a Remington model of 1858. The question at hand is the unit stress in the elements that transfer barrel loading to the frame (or the rear portion of the Remington's frame).
The R-58 has one piece frame unit with a large central opening bounded by top and bottom straps that transfer the load between the front and rear portions. The cylinder pin is free floating and doesn't resolve any portion of the load.
The Colt F-model has an "L'' shaped frame with a cylinder base pin. Loads from the barrel are transferred to the base pin via a wedge in double shear and to the lower portion of the frame (strap) via a simple bearing surface with two locating pins.
During the firing event, a load is first applied to the barrel as the ball departs the cylinder and contacts the barrel's forcing cone. Until the ball exits the muzzle, the barrel and chamber act together as an expanding-volume pressure vessel (with leaks at the forcing cone gap and nipple hole). The majority of the pressure is taken by the walls of the bore and cylinder with some reacting against the base of the bullet and the back of the cylinder. This generates equal and opposite forces between the barrel and the back of the cylinder, and puts the barrel's restraint in tension.
In the R-58, the barrel's forward load [P] is transferred to the front frame section via a threaded connection. Then, the two straps distribute the load to the rear portion of the frame. Since the bore is unevenly spaced between the straps (see schematic, below), the upper strap carries roughly .75P and the bottom .25P. Using your numbers for the area, this equates to a unit stress of [.75P/0.1462] 5.13P psi for the upper strap and [.25P/0.0384] 6.51P psi for the lower strap.
With the Colt F-Model, the barrel's forward load is transferred to the barrel wedge and to the lower strap bearing surface. As is typical with all bearing surfaces, the lower strap can transfer only compressive loads (the pins are for locating and aren't moment resisting). Since the barrel isn't located between the reactions, the load can be resolved as a cantilever (see schematic, below). Using the dimensions of my specimen and your numbers, the base pin is in tension 1.625P with a unit stress of [1.625P/0.1466] 11.08P psi and the base strap is in compression .625P with a unit stress of [.625P/0.0982] 6.36P psi. Note, the stress in the base pin will increase at the wedge-way.
From this, it appears the Remington's maximum unit stress is (6.51/11.08) about 59% that of the Colt.