Here's a cartridge that has been around for about 80 years, and it started as a "wildcat" (home rather than factory developed). Ned Roberts came up with the idea of necking the 7X57mm Mauser down to 25 caliber (.257-inch bullets), but he reduced the shoulder angle of the Mauser round to a sloping 15 degrees. Remington liked what they saw; a rifle with light recoil that was very capable of taking deer. They added it to the cartridge lineup for their Model 30S Rifle, but went back to the original 20 3/4-degree shoulder. Winchester hopped on and chambered it in their Model 54. When Remington introduced their Models 721 (long action) and 722, the Roberts came along in the short-action rifle. In later years, the 257 Roberts made it into Ruger's Model 77 Rifle, but they were wise to use the standard-length rather than the short action
Today, someone might ask why it is still around. Good manners. That's the reason. While it has a smaller case than the 25-06 and can't match its speed, it is also quieter, has noticeably less recoil, and essentially does the same job. It won't die, or at least hasn't yet, because a lot of gentlemen gun writers like it and have continued to say nice things about it.
In 2006, I had the Remington Custom Shop build me a 40-XBBR in 257 Roberts. Regular 10-inch twist, 24-inch barrel. I was curious as to how well a standard Roberts could shoot, and the accurate bench rest version of the 40-X would tell the story. The answer: very well. It's not competitive in the world of bench rest shooting, but it has no problem staying in the threes and often making it into the twos. That means three tenths of and inch range, and two tenths. Groups that are typically in the quarter-inch to third-of-an-inch range. There's something very pleasant about taking this modern, green-stocked single shot — chambered for a classic old wildcat — to the range and letting interested persons try it. Want to put a smile on a lady's face? Let her punch a hole, on her first try, through one of those thumbprint-sized orange target stickers at a hundred yards. And then let her follow up with two more shots in the same place.
The Roberts, as most people refer to it, drives 100-grain bullets out of the muzzle at about 3000 fps with several powders. I prefer IMR 4350 with the100-grain Sierra MatchKing, but for showing off in the accuracy department I load them to about 2850 fps. I've tried H4350 with similar success. The same powder(s) work well with 115- to 120-grain bullets. It's a simple cartridge to reload.
For varmints, if you don't need to save the pelt, 75-grain bullets moving along at about 3400 to 3500 fps can be very impressive. The same is true for 85- and 87-grain bullets at about 3200 to 3300 fps. With the lighter bullets, sometimes the 4350 powders don't work quite as well as others that are just a little faster. This is a rifle-to-rifle situation, and it makes good sense to always consult loading manuals for trustworthy information when developing a load.
As with a number of cartridges, the 257 Roberts has an "Ackley Improved" version. P. O. Ackley was a renowned gunsmith, barrel maker, and cartridge designer, and his improved cartridges typically feature a "blown-out" (fire-formed) case with a nearly straight (little taper) body and a 40-degree shoulder. The 257 Roberts AI gains about 200 fps over the standard Roberts, which puts it right up there nipping at the heels of the 25-06. For me, the difference isn't necessary. If I want to sizzle quarter-inch bullets across the prairie, I'll reach for that Accumark in 257 Weatherby Magnum.