There is no reason.
The 243 outperforms the 22-250 at long range (higher bc offerings in 6mm).
The 243 has better big game bullet selection.
The 243 shoots 55s faster than 55s from the 22-250, and has higher bcs to boot.The 243 can easily be loaded down to 22-250 levels of recoil.
The 22-250 kicks too much for high volume varmint use.
The 22-250 makes too much noise for high volume varmint use.
The 22-250 burns barrels out too quickly for high volume varmint use.
The only thing the 22-250 does well compared to the 243 is shoot slightly cheaper and slightly higher bc 70-80 grain bullets. Big effin' deal.
The 22-250 is a 'tweener, and its day has passed.
I'm not saying that is false but I don't see it as very likely. Generally speaking, taking a bullet of a given weight and making it shorter and fatter lowers bc. A certain amount of that can be overcome with bullet profile design. With equivalent design, however, the .22 should have a higher bc.
Also, is the .243 well suited to high volume varmint use? I would have said not.
The .243 was designed and sold as a tweener. I've got little interest in either of these cartridges but I'm not sure much of the argument for the superiority of the .243 is based in real world differences. I would rather use a .243 deer sized game or long range shooting. That I agree with but I wouldn't chose it with all of the 6.5's available.
Listed bcs:
The 22 caliber 55 grain Ballistic Tip has a .267 BC.
The 24 caliber 55 grain Ballistic Tip has a .276 BC.
I agree with you that the BCs should be the other way around in theory, but this is the way it works out with the Ballistic Tip. The Blitzking is the other way around, but I prefer the Ballistic Tip as it holds together and drives deep, working for deer as well as varmints. Vmaxs aren't a direct comparison, as they make a 55 grain 22 caliber but a 58 grain 243, and the 22 is flat based.
The 243 isn't well suited for high volume use either, but that wasn't the point. The point was that if dropping down to 22 caliber, one thinks "varmint", and a 22-250 sucks for high volume varmint use. It kicks too hard to see hits in the scope at the ranges most small varmints are shot, makes enough noise to quickly drive colony varmints underground, and shooting 500+ rounds through one a day means a lot of expense and the barrel won't last long. The 22-250 is superb for coyotes and the like, but so is a 243. But really, neither is my fave if keeping hides.
I came to these conclusions after owning two 22-250s, one of which was shot enough to need a new barrel, as well as having a couple other large capacity 22s around to draw conclusions from. I've owned and shot the wee out of something like a half dozen 243s. So this was based on real world experiences and observation of differences.
