If a tang mount aperture is out then the next best rear I know of is a wide flat top with plenty of light around a wide front blade. Stay away from the buckhorns which do not give as good of definition of elevation and are poor on horizontal moving shots of game.
* The .40 Cal rifle weighs 7lbs, has a 46" barrel that is Swamped A weight. It has a set trigger, it is 62" OAL and has a Cherry stock that is a Southern Mountain Rifle configuration. Length of pull is 13 3/4".
I agree on that, although a buckhorn can be modified to provide what I think of as "elevation indices". And if you're not shooting at game, the horizontal movement issue doesn't arise. Still, I think the buckhorn (of course mounted somewhere up the barrel and not as a true aperture sight) suffers from a sort of fundamental visual sloppiness. I spent a long time experimenting with one, but finally retreated to the original flat top notch sight. My front blade now sports a tiny length of fiber optic glued to its top edge.
Still trying to get the height of that exactly how I want it. 
Being a hobbiest gun mechanic for the last 40 plus years I've had occasion to fabricate and try various sight types and about 20 years ago came across the idea of putting brass tops on bladed front sights with a 45 degree angle to the rear face. This angle will catch any available light and is one of the best I have found to hold elevation on game or target. Most of the blades I have milled for various gun projects are .100 wide and show up very well in the sight radius lengths of around 30 inches which is common for tang mounted apertures. This width will also work well for barrel sights which are usually much closer together. The technique is to hold six oclock on target or game. The width of the front sight is what holds the elevation profile so well in contrast to the rear sight wide flat with lots of light showing around the front sight.
I like it. I've though of doing something like that myself, but didn't want to dig into that project. Nickel would work too. But I think you do need to be concerned about the glare coming off such a piece. So brass is probably better. But the idea is great because it provides more contrast between front and rear sight and between different parts of the rear sight. Contemporary pistol shooters don't have white or hi viz inserts or dots on their rear sights just because it looks cool.
Yeah, that's a problem. But you can tinker with the effect to some degree by the color you choose, the size, and the angle of the rear surface. I'm still tinkering a bit. Because of this effect, a fiber optic dot seems often to "look bigger" than a similar dot that's just white plastic or ivory or brass.
Not for me. Nickel probably works the best for me -- among the metallic materials. But white is best.
You could just use a thin, silver front sight post. They come in different heights, and are easily adjusted with a fine file down to the proper height. They are available from Track of The Wolf. I put thin silver on my rifles.
mostly aesthetics (reminiscent of the older "cannon muzzles"); and it gives the impression of a higher-value gun, as it takes substantially more work to produce swamped barrels than any other shape. There were also plenty of tapered and straight barrels pre-1830's, both in Europe and in the European Colonies in North America. You do see a few guns with flutes in the barrels pre-1800, but the mills needed to do those consistently and in a time-efficient manner didn't really show up until the 1810's, and then primarily in the hands of State Arsenals and large firms.
Thats why we move the rear sight forward until a good sight picture can be had. My rear sight was set 16 years ago, and I can still see both sights. Looks a bit silly, but shoots.
Beauty is not a quality dependent on long or short, in my opinion, but on form. function, workmanship, choice of wood, and tasteful carving/engraving. I am not impressed with a lot of needless decoration of any sort. That said I love a tastefully designed and built gun, regardless of its size. I love 'em all but just don't put a brass lizard on a iron mounted deer rifle. My 1 1/2 cents worth. Polecat
