The favorite choices, both on this site and AR, are .405, .30-30, and 38-55, in that order. On AR there are several people who seem to want to press for the 9.3x74R. The 9.3x74R operates at more pressure than the above three cartridges and requires longer chambers than any of them. I tried to explain that building the rifle in 9.3x74R will result in a rifle at least 1/2 lb heavier. But the long 9.3mm apparently has some die hard fans.

I am contemplating a true custom rifle with receiver and barrels built to the specific caliber. Many companies use one or two frames to build guns of several calibers. The best example that comes to mind is a .410, 28ga, and 20ga all built on a 20ga sized action. Doing so results in a perfectly sized 20ga, an over sized heavy 28ga, and a bulky .410 with ponderous chambers and barrels. The rifle I am considering would be perfectly sized for the caliber - action, chambers, and barrels.

The .30-30 would give me a handier, lighter rifle than the .405, and with the large selection of standard .308 bullets available it would seem more versatile. But it would be regulated for a single factory load and I could probably only get a few different .308 bullets to regulate.

The .405 is tempting because of the additional power. It could, and would, be built smaller and lighter than a 9.3x74R but then there is the issue of recoil in a light rifle.

The .38-55 seems like it might be the best compromise between the .30-30 and .405. The rifle would be both light and powerful (for the intended purpose). But I am wondering about the bore. A true .38-55 bore is a few thousandths larger than the standard .375 bore. If the rifle had a standard .375 bore could I shoot .38-55 ammunition in it without trouble? If the answer to that is "yes" then that would be a big plus.

I have a couple of rifles in mind. One has a stronger action than the other but that also makes it a little bit heavier for caliber. Handling would be a little different between the two. I would use the less strong action (I don't want to say weaker because it isn't weak) for the .405 to keep it light for caliber and handy. I would use the stronger action for anything smaller. The rifle would be a SxS with action made of steel. That would make for a .405 rifle of ~7lbs and a ~6.5lb rifle in something like .30-30 or .38-55.

So, as you can see, I am still contemplating.