Oldies but goodies
Tamara at http://booksbikesboomsticks.blogspot.com/ has a link to her "Cosmoline and Rust" blog http://cosmolineandrust.blogspot.com/2007/08/sunday-smith-9.html where she points out that the Smith and Wesson M&P revolver in .38 special has been in continuous production since 1899, 4 years before the Wright brother's first flight, 7 years before the patent on the tungsten filament light bulb.
I, too, am enamored of older designs from the steam era. the 1891 Mosin Nagant rifle was still in production in 1995. The 7.62X54R round is still standard for several countries around the world. My own version was made in 1932 in Finland, and has the SA stamps and dovetailed fore-end for the Finnish Army. There has to be a few gory stories of how that particular rifle served! Finnish Mosin-Nagants tend to have half the error of the usual Soviet Russian editions, in part because the dovetailed stock fixes the tendency for the wood to warp and deform the barrel. The oddly complex bolt was designed to get around the Mauser patents. In so doing, it was more successful than the Springfield '03, for which the US ended up paying royalty payments to Mauser. It also is absolutely bombproof, an important consideration for any nation trying to field and form a large conscript army made up of mechanically illiterate peasants.
Now if I can find an old Remington Model 8 (or the later Model 81). Another wonderful transition rifle, it uses a detachable box magazine, a stripper clip loader, and a spring loaded recoil operating system. The bolt itself locks directly into the barrel with a rotating lugged bolt, rather like the M-16. The safety is on the right side of the receiver, and looks like the prototype for the Kalashnikov safety. Chambered in .35 Remington for the East Coast, or .300 Savage (later itself modified into the 7.62X51 NATO) for the rest of the country, it would be fully capable as any modern rifle. Since it had no gas operation system, clogging of the port or piston could never be a problem. I imagine that the operating spring located between the barrel and the sheet metal sleeve would heat up, and could even lose some tension, leading to failure to cycle. On the other hand, it had an easy takedown lever which would made it very effective for Paratroops.
My Savage 99 lever action is another design from that era, in .308 Winchester, another modification from the .300 Savage, but with a rotary internal magazine. I still hope to take this to hunting camp, but the Boyd stock is a few inches long for me. Cutting it off, and replacing the rubber pad with a proper Savage butt plate is a project that I will have to complete this summer.
Tam's blogs are always fun for me to read. She is a great writer, and includes pictures from the magnificent Oleg Volk. Gosh, I love the internet!