Posted on 02/24/2003 4:35:32 PM PST by 45Auto
Shooters have always enjoyed trying out different rifles and cartridges through trading and borrowing, or simply being called on to sight-in new rifles for their friends. They have been aware of all the new offerings put forth by the manufacturers and eagerly await the various shooting magazines every month just to see what new rifle or cartridge might be announced. They have not been disappointed. But even though this meant reading and dreaming a out all those fine new offerings, the fact remained that most continued shooting the three or four cartridges they had been using for years. Since many of these shooters were hand loaders, and therefore basic experimenters, the new hype of fabulous cartridges didn't seem to add up to anything very new, or at least not much better than what they were loading. If they wanted to change from what they had, they certainly had more interest in going their own way and not simply following the crowd, buying every new offering coming down the pike. Any change would have to mean something different, but something that would not push them over the edge into anything tricky or perhaps dangerous. This of course meant investigating the cartridges not being loaded by the regular manufacturers.
Experimenting and developing something different in rifle cartridges seems to be in the blood of many riflemen. But to move from standard, Sporting Arms and Ammunition Manufacturer's Institute (SAAMI) specified cartridges used by the factories to something very different can be a quantum leap for the uninitiated. All too often a rifleman gets stampeded hurriedly from his factory loadings straight into a Wildcat…and too often a very wild Wildcat! This leads to much frustration and often causes one to drop the whole idea and never go there again. To avoid this, the move has to be made carefully. Thus, the first move away from SAAMI cartridges by a novice experimenter should be by way of the simplest and safest homemade cartridges.
In the cartridge world there are three basic types: (1) Standard factory offerings; (2) Improved; (3) Wildcats. Factory offerings include cartridges that are chambered for on a regular basis plus those that are still in demand for use in old, discontinued rifles. Many of these are on their last legs and will eventually become obsolete. Improved cartridges are modified factory offerings, changed by experimenters in a manner that generally increases powder capacity and therefore offers improved ballistics. The unique thing about Improved cartridges is that the original factory cartridge will still be accepted in the new Improved rifle chamber and can be fired safely. Wildcat cartridges are those that are not commercially loaded and are designed so that no other cartridge can be safely fired in the Wildcat chamber.
Here we should detail the description of the two cartridge categories of interest to experimenters. The first understanding of non-SAAMI cartridge nomenclature is a full and proper meaning of Improved vs. Wildcat cartridges. The Improved cartridge is one that has been changed just enough to give improved performance in some manner, but still allow the use of the standard cartridge in the Improved rifle chamber. In other words, it still must headspace close enough to the regular factory cartridge to allow both cartridges to be used in the Improved chamber, and to do so safely. These Improved cartridges are commonly formed by simply firing a factory round in the Improved chamber to blow the case out to the desired shape. The resulting case can then be reloaded to provide the improved performance. And of course the new Improved case will not enter the regular factory chamber. A Wildcat, on the other hand, is a cartridge designed different enough from any factory cartridge that no factory cartridge can be fired safely in the wildcat chamber. These Wildcat cases must be formed in some sort of forming dies prior to being loaded and fired in the Wildcat chamber. This process can range from extremely complicated to very simple, depending on design. Any beginning experimenter entering the Wildcat field needs to understand that there are many cartridges that carry misleading names, names that indicate an Improved cartridge, but in reality are pure Wildcats that cannot be made by fire-forming any factory cartridge. An example of one of these is the popular 6.5x06 Ackley Improved cartridge. Since there is not a U.S. standard 6.5x06 factory cartridge, there is nothing that can be used to simply fire-form into the so-called Improved cartridge. An even more interesting misnamed cartridge is the 6.5x55 Improved Arch. It is a pure Wildcat requiring special forming dies, and the standard 6.5x55 Swedish cartridge cannot be fire-formed in the Improved Arch chamber without possible exciting consequences such as a blown up rifle! The Arch case was originally started from the 6.5x55 Swedish case, but changes resulted in the headspace becoming radically different. On the other hand, the 6.5x55 BJ Ackley Improved cartridge is a true Improved in that the cases are formed by simply firing the 6.5x55 Swedish cartridge in the Improved chamber to safely increase capacity and performance by something more than 10%.
There are dozens of other properly named Improved cartridges available including the Ackley series of the .22-250 Improved, .250-3000 Improved, .257 Roberts Improved, 7x57 Improved, .30-30 Improved, .30-06 Improved, etc., etc. It should be noted, too, that there are several versions of the same factory cartridge that show up as Improved, and any experimenter must evaluate them carefully to determine whether or not they are properly set up, or perhaps have been changed enough to become a pure Wildcat cartridge. As an example, the fine .257 Roberts cartridge has been improved by many gunsmiths to some design they preferred and it can be found with several different names, shoulder angles and body tapers, but all retain the same safe headspace…hopefully! And I say hopefully because any shooter starting into experimental cartridges must check and assure the headspace is correct for the particular design. Another interesting example is the .25-06 Improved. It has been experimentally produced under a dozen or more names, including Ackley, Mashburn, ICL, Vickery, etc., but all, again hopefully, with the same headspace required to allow it to be a true Improved cartridge. Factory .25-06 ammunition can be fire-formed to any of these designs.
Anyone entering the experimental cartridge field, whether with an Improved or Wildcat cartridge, must have an understanding of correct headspace for the particular cartridge. Many gun shops cut incorrect chambers for Improved cartridges because they know only enough to make themselves dangerous! They often take the seemingly correct stand that since both the standard factory and the Improved cartridges can be fired in the Improved chamber, both must have the same headspace. This is totally incorrect and will result in backed out primers, blown primers, ruptured cases…or worse.
Since most cartridges today are of the rimless type, we will discuss only that configuration for headspace. Headspacing is normally considered to be the distance from the face of the locked bolt to a point on the case shoulder called the datum line. This line is arbitrary to a great degree, being a point where the diameter of the case shoulder is .375" in most cases. Some use different diameters as datum points, and one in particular, the original Government .30 caliber (.30-06) does not use the datum point at all but uses the point where the shoulder joins the case body. Commercial .30-06 cases use the datum point. When we start changing things, such as forming the Ackley 40 degree Improved chamber and cases, we no longer can use this datum point for headspacing, but must use the juncture point where the neck joins the shoulder. In standard chambers some part of the case shoulder, including the datum point, would contact the chamber to provide proper headspace. But when we cut out the chamber in the shoulder area, as well as some along the case body area, to change to the Improved configuration there is no longer any support for the shoulder of a standard case. Therefore, headspace is no longer provided by the datum point and shoulder area of the chamber. The only point of contact will be the neck-shoulder juncture. This is a very fine line…. And headspace is now held between the bolt face and this neck-shoulder juncture point. The shoulder of the standard factory case is no longer supported by the chamber wall.
To assure that even the shortest standard cartridge brass will fit this Improved chamber snugly, without shoulder support, the standard headspace must be reduced by .004" from that of the factory, or SAAMI, specifications. This now causes the standard SAAMI headspace "GO" gauge to not fully enter the chamber. Thus, the standard "GO" gauge becomes the "NO-GO" gauge for use in Improved chambers! As an example, the standard .250 Savage "GO" headspace gauge in the .250 Ackley Improved chamber will not allow the bolt to close. This is required because the manufacture of pliable brass cartridge cases can not hold the neck-shoulder juncture point exact, and we do want the standard cartridge to fit rather snugly at this point in any Improved chamber.
Once a shooter has mastered the design and proper headspacing of true Improved cartridges he will have covered many of the basics of Wildcat designs. Usually Wildcat cases have to be formed first in some manner other than fire-forming. The most common changes made in designing a Wildcat include moving the shoulder one way or the other, changing the body taper, cutting the case length, and of course necking to a different diameter. There are a few Wildcats that are rather easily formed. Others require special tools and lots of soul searching…. Since this article is not intended to describe the most difficult and exotic Wildcat designs, but is aimed at simply helping get newcomers started, we will describe the forming of a couple of simple Wildcats.
One of the easiest Wildcat cartridges to form is the .256 Newton, a factory cartridge until 1938, and today a pure Wildcat because there is no existing factory brass available. It is often described as a necked down .30-06 cartridge, but that is a simplistic description. The cartridge is actually a good bit shorter than the '06, the shoulder is steeper and of course the neck is reduced to 6.5mm. The rim and head diameter, as well as the body taper, remains about the same as that of the '06 which is the same as the .270 Winchester and .25-06 Remington. When using the .30-06 case a lot of brass will be lost in trying to neck the .30 caliber down to .26, or 6.5mm. Therefore it is best to start with .270 Winchester cases. Necking those down to 6.5mm will show no case loss. The problem then becomes that of moving back the shoulder and arriving at a headspacing point where the neck and shoulder join. This can be done very well by using a standard full length sizing die for the .308 Winchester with the decapping rod removed. By simple trial and error the die can be screwed into the press just deep enough to set the point of the body and shoulder (measuring 1.896" from the head) for the .256 Newton. This point should be correctly set, but if it is slightly off it makes little or no difference just so it is established short enough so as not to bind in the chamber. In other words, that point can be a few thousandths short in head to shoulder measurement. It will fire-form later to become correct. Once this outer shoulder point is established you will be left with a very long, two step neck of a short .30 caliber section (from using the .308 die) plus the original .270 neck.
The next step is to simply run this partially formed case into the regular full length .256 Newton sizing die with decapping rod. This will reduce the neck to 6.5mm, and push the neck-shoulder point back to its proper location. This point must be correct because it will become the headspace point. The shoulder may now appear a little uneven, but close to proper shape. By trimming this case to 2.44" length, it is ready to load and fire-form in the Newton chamber. When this case is fed into the rifle chamber, it absolutely must have a slight crush fit to assure that the neck-shoulder juncture point is long enough to hold the headspace securely. As with any fire-forming, the load should be rather stiff to assure fully forming the shoulder on the first shot. After inspecting the new formed .256 Newton case, it is ready to load and use.
Another easy to form Wildcat is the excellent 6.5x06 Ackley Improved, a cartridge that is not a true Improved model, since there is no U.S. factory cartridge to improve. This is a full-blown Wildcat cartridge, one that can be loaded to equal the big boomer .264 Winchester Magnum, and do so with less powder. This is also another case where the .30-06 brass is commonly recommended, but when used will result in considerable case loss. It is better to use the .270 to prevent this loss. Even though the .25-06 brass is closer to the 6.5mm neck diameter, .257" vs. .264", it is best to use the larger .270 so as to be able to retain a very small false shoulder where the neck joins the shoulder of the finished 6.5x06 Ackley. This helps assure snug headspacing fit for initial fire-forming. To form this case you simply run the .270 case into the full length 6.5x06 Ackley die, with the decapping rod left in. The die should be backed out about ¼ turn so as to leave just a little of the .270 neck sitting where the neck-shoulder juncture begins. This is the false shoulder mentioned above. Trim the case to length and try it in the chamber. If it is too tight, screw the die down 1/8 turn and resize the case again. It should fit the chamber with just a little jamming feel. This will assure the headspace is snug, and the case can be loaded and fire-formed.
There are 6.5x06 Ackley rifle chambers that are somewhat large at the exact juncture point of the neck and shoulder of the case. This will cause the false shoulder of the .270 case to perhaps offer no closing feel when chambered. If this snug fit can not be felt, case necks should be expanded even larger than .270 for the false shoulder. A 7mm neck expansion always cures this, but will require the .270 neck to be expanded to 7mm (.284) before running the expanded case into the regular 6.5x06 Ackley die, and proceeding as above. It might appear that simply using .280 Remington brass would be easier. But this brass is about .050" longer from the head to neck-shoulder point and would have to be set back. While I have read that this can be done by simply running the .280 into the 6.5x06 Ackley die, I have not tried it. Pushing a total shoulder back very far in a sizing die is tough, if not impossible, to do. But since the shoulder area of the 6.5x06 Ackley Improved die is changed to a 40 degree slope, the top point of the shoulder is obviously moved forward, leaving some room for the longer .280 shoulder to push into without being forced. The only part of the .280 brass that would then be moved would be the small amount near the neck-shoulder juncture. And that should move back easily. But since there is a lot more .270 brass available, I have always used it by simply expanding the neck up to .284 if needing a slightly larger false shoulder for proper fit. Thus, the simple way to handle any need of a larger false shoulder is to expand the .270 neck to .284 first, then proceed as described. The fire-forming load can be one of the top loads listed in a loading manual for the .25-06, provided the same bullet weight is used. This will provide enough chamber pressure to fully form the case with one shot.
Wildcat cases of many shapes can often be formed by experimenting with your existing loading dies. Years ago when we lost our supply of PPC brass many of us found that by utilizing a good number of our regular dies we could form the PPC from standard 7.62x39 brass. It looked crude when formed, but fire formed out to a nice looking PPC…and we did not have to purchase the very expensive forming set! Many Wildcats can be formed in this manner, but it might require a lot of measuring and trying. And if you plan to load lots of your favorite complicated Wildcat cases, you probably would be better off by ordering the proper forming set from RCBS.
Start your move from standard factory cartridges with the excellent Improved cartridges first. You may never find a need to move on into the Wildcat field, but if you do, learning about the Improved cases first will pay off, big-time. Keep shooting.
For me, there are really good factory cartridges for just about any purpose.
It kicks out a 200 gram bullet at 7800 FPS without hitting the maximum loads in the loading tables. Kicks hard but really performs.
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