You don't hear a lot about the 30/40 or as I prefer the 30 Army but it has become my favorite cartridge for a number of reasons. Six years ago I had CPA build me a 44 1/2 in the above mostly because I've always admired the cartridge's brief but colorful history and because I just wanted one. Five thousand rounds later I have gained some insights about the cartridge that might help any one that wants to load it. When I started out I tried bullet weights from 110 grains up to 220 grains and at least a half dozen different powders. My barrel has a .3078 bore diameter with a one in 12" twist. Regardless of the load, the 220 grain gas check bullet proved to be the most accurate. This is not surprising when you remember that this was the original bullet weight adopted by the government. The velocity of the original government load was 2200 fps but they soon realized that that was a bit to ambitious for the Krag action and so they dropped it down to 2000. My pet load is 22grains of IMR4198 which gives me a velocity of 1850 fps and is very accurate. IMR 3031 is my second choice and both shoot near MOA. On the flip side of the coin 2 grains of Red Dot with a 110 grain bullet makes a delightful gallery load that cuts one ragged hole at thirty yards and is the bane of barn pigeons for miles around. It's also great indoors with a minimal back stop required. Brass in all loads lasts forever if you anneal them now and then.  To date I've taken Caribou and a number deer with this rifle and the bullets cast in wheel weights have performed admirably, one shot, one critter, which is how it should be. So give this old war horse a look, you won't be disappointed.

I have a Cimarron (Uberti) High Wall in 30-40 and really enjoy loading for and shooting it. It seems to be every bit as accurate as my three Browning/Winchester Miroku High Walls. The "set-only" trigger is the only possible drawback.

One of my favorite cartridges.  I have a Shiloh saddle rifle with half round/octagonal standard weight barrel.  Mostly I shoot 190 grain cast bullets with it.  Great rifle and fun to shoot.   Made in 1985 or 6, probably the first or second 30-40 made by Shiloh.   Also have a 1895 Winchester in 30-40.

George

Here are some 100 yd groups, shot with the HW before I rechambered it, with both cast and jacketed bullets.

I have an 1898 Krag rifle that had been converted to a PALMA rifle  for that competition at about the time the 30-03 was just a baby.
Still in excellent condition and still able to compete.