Even the name of this wildcat cartridge is suspect. The 219 Zipper was introduced by Winchester in 1937, chambered in their somewhat re-engineered Model 94, designated the Model 64. The cartridge itself is simply the 25-35 Winchester necked down and with a bit shorter neck. The 25-35 belongs to the 30-30 family of cartridges, a fact easily seen if you compare it visually to the 30-30. The 219 Zipper in the Model 64 didn't gain a great reputation among varmint shooters, as the 220 Swift was available at that time in a bolt-action rifle. The lever gun, however, did appeal to some hunters who were less interested in extended ranges. Fact is, a nice, unmodified Model 64 in 219 Zipper today is a valuable collectible.
Back in those days, especially after World War II in the later 1940s, there were a scattered number of inquisitive handloaders around the country, tucked away in their own private corner of a basement or garage, who liked to try to improve on what was already available. The 219 Zipper case is quite tapered, and has a sloping shoulder. What if it could be shortened, the shoulder made sharper, and the case blown out (fire formed) straighter? Would that improve its performance? Well, maybe. The performance insofar as velocity was concerned didn't change much. The Wasp wasn't really any "hotter" than the Zipper. At least not much. The tendency for the wildcatters is to load hotter when such things are being developed, and that's when the rumors of fantastic performance surface.
A fellow by the name of Harvey Donaldson has been given credit for the most well known of the Zipper improvements. He arrived at what was to become a popular cartridge for bench rest competition already in the late 1930s. By 1940 the Wasp was ready to go, but so was WW II. Skip to the post-war years; that's when the finishing touches were determined, and the Wasp went on to victory in match after match. Its demise began with Remington's introduction of the Model 722 and the 222 Remington cartridge in 1950.
I knew one person who was a WW II veteran, cartridge experimenter, and ultimately an engineering and tooling-development manager at John Deere. He built a 219 Donaldson Wasp using a Winchester single-shot high-wall action, and set about kicking almost everybody's butt with it. Incidentally, during that time the cartridge was simply called the 219 Don, and that's how his barrel was stamped. I know this because I still have the rifle. But here's something he discovered...
Considerable body taper, or straight taper, and a whole lot of other things you can do to fiddle with the appearance of a cartridge, don't really matter all that much. What does matter is case preparation, and wildcatters tend to provide a great deal of attention to that. If someone was to take a common cartridge and spend plenty of time making sure that 20 or so cases were beautifully matched, even if the cartridge was not touted for its accuracy, what do you think would be the result? Well, I did just that with a Remington 40-X single-shot action, and a superb barrel chambered for the 250 Savage. Look out! We're dealing with tiny itty-bitty groups here that are the size of shirt collar buttons. There's an Ackley-improved version of that cartridge with a straighter case and 40-degree shoulder that produces more velocity, but accuracy with well-prepared cases is essentially the same as with the standard case. Further, there was a verbal claim that someone had built a 1950s bench rest rifle on the 219 Zipper case, and he went out to win match after match.
In the mid-1960s, Winchester introduced its factory version of the 219 Wasp. The 225 Winchester was designed as a semi-rimmed cartridge with somewhat more capacity than the Wasp, and therefore higher velocity, but shooters bypassed it in favor of the old wildcat 22-250 made legitimate by Remington. It must be all about velocity. The extra 100 fps of the 22-250 killed the 225 Winchester, which had a tendency to be more accurate in a full-house, custom-built rifle than the same quality 22-250. All one needs to know, if he has a 225 Winchester, is where to get a supply of good 53- to 55-grain bullets and IMR 4064 powder.