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Join Date: Oct 2007
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First, a little bit about definitions:
A standard cartridge is a cartridge designed and/or developed by one of the major ammunition or arms manufacturers or by a government arsenal. (30/06, 270 Winchester, 308 Winchester, 7mm Remington, 300 Savage etc.)
A Wildcat cartridge is a cartridge derived from a standard cartridge and is produced by changing bullet diameter, or altering case shape or configuation, or by shortening the original case or by doing all three. (270 Gibbs, 7mm Gradle Express, 22 Cheetah etc.)
An "Improved" cartridge is a cartridge which is altered in shape by firng the standard case in the "Improved" chamber. (280 AI, 303 Epps, 30/06 AI etc.)
Some cartridges start out as wildcats and become factory offerings later on (22/250 Rem, 257 Roberts, 25/06 Rem, 35 Whelen etc.) Others start off as factory cartridges and become functional wildcats due to obsolescence (256 Newton, 33 Winchester, etc.).
The impetus for designing a wildcat cartridge is often stated as being for improved performance but since performance is seldom improved to any great extent, the desire for something different is probably closer to the truth.
There are often some pretty extravagant claims made for wildcats by the originators. When these claimed performance levels are achieved, it is often done by loading to extremely high pressures. Rocky Gibbs freely admitted that his heaviest loads could only be used in certain types of brass which were harder and better able to handle the excessive pressures. The truth is, a standard 30/06 loaded to the same pressures will come very close to the figures produced by the 30 Gibbs. Not the same because, in the arena of cartridge performance, size matters. Bigger is always faster if all else is equal but sometimes, not by much. One thing which is certain, there is no magic in case shape or in the headstamp.
Those wildcats which became factory cartridges usually did so because they were very good, reasonably designed, cartridges. The 22-250 was and is an excellent cartridge. So are the 25/06 and the 35 Whelen. Cartridges which did not become factory offerings usually did not simply becaus the market wasn't there, in some cases or because the cartridge didn't offer anything apart from novelty.
There have been some wildcats which achieved relatively significant popularity but never were adopted by the factories. One which stands out in my mind is the 30-338 Magnum. This is the cartridge everyone expected Winchester to introduce as their 30 caliber magnum and it would have been a great one. The trouble was, the already-established 308 Norma was slightly larger and the sales people were afraid the Winchester might suffer by comparison so they designed the physically larger but ballistically identical 300 Win Mag instead.
Another wildcat which has been so universally popular and successful that it is difficult to understand why it was never legitimized is the 6mm PPC (the 220 Russian necked up and blown out). This cartridge is so dominant in Benchrest competition that it is rare to see any other cartridge being used but it remains a wildcat except for a few rifles and some ammunition offered by Sako. On the other hand the 6BR Remington, although a factory cartridge, never achieved similar popularity levels because, although it was a factory cartridge, formed brass was not available until many years after it's introduction.
Improved cartridges have long been hyped beyond their real abilities but some are quite good cartridges, nonetheless. One, the 280 AI, has even achieved legitimacy although the cartridge, as finally specified by Nosler, is not quite the same as the original Ackley Improved. The 280 AI outperforms the standard 280 significantly but only because it is loaded to higher pressure levels. Loaded to the same pressures (and there is no reason not to do so) the difference in performance is on the order of 2%. This is true of all of the improved cartridges based on 30/06 brass. The fireforming of the parent case simply does not increase capacity enough to net a huge velocity increase.
Some of the theoretical advantages to wildcat and improved cartridges sound great but are simply not true. One claim is that the minimal body taper design reduces bolt thrust. At pressure levels where bolt thrust might matter, this is simply untrue. Another is that the sharp shoulder stops brass from flowing forward as it is subjected to high pressure loadings. Again, not really true. Brass which is taper and has a sloping shoulder doen't flow forward from firing either. Improved cartridges generally do not lengthen as badly during full length resizing. Some of this may be due to the shrp shoulder and reduced body taper and some may be due to a closer match of dimensions in rifle chambers and resizing dies. In any case, trimming is indeed less frequently needed.
Another reason trimming is less frequently needed with an improved case is because they shorten up quite bit when fireformed. A wildcat of "Improved" design I have worked with illustrates this quite well. The 303 Epps is a 303 British which is blown out to a minimum body taper, sharp shouldered design. This cartridge was designed and eveloped by Elwood Epps, a Canadian gunsmith. I built one for myself but built it on a 30 caliber barrel so mine is a 30-303 Epps. When standard 303 brass is fireformed it shortens up by at least thirty thousandths of an inch. It will never stretch enough to need trimming unless I go out of my way to make it do so.
By the way, the Epps cartridge, once fireformed, ends up having slightly less powder capacity than does the 30/06 (roughly 3% less). It is not too surprising therefor, that it produces about the same velocities as a similarily built and loaded 30/06. One thing which can be said for the rimmed 303 case is that the brass is very strong. In addition, the design of rifles using the cartridge is such that the case is almost entirely enclosed in the chamber. For these reasons, it seems to be possible to load 303 or 30/40 Krag brass to surisingly high levels with no failures. This assumes the rifle action is a strong one, of course. Not true with the Lee Enfield or the US Krag.
In the end, by making up my 30-303, I have a rifle which will perform just like the 30/06's I have in the rack but with considerably more effort required.
The 6PPC is another cartridge I have worked with which shows the same shortening during fireforming. Of course, since PPC chambers are cut to very precise dimensions (at least they should be), working of the brass is minimal so it is no surise that they don't stretch.
Ultimately, there is little real need for any wildcat cartridge but using one allows the shooter to feel a bit more individualistic and to feel some pride of accomplishment in forming, loading, and shooting something which is not the same as everyone else's. For many, this is reason enough and everything else is just window dressing. GD