Ray “Hap” Fling, a former All American Trap shooter from Ohio who now lives in Gainesville, Florida occasionally shot trap with the inventor of the plastic wad/shotcup in the ‘50s. The original, red plastic wad is marked “Pat. Pend.” on the powder side. On the shot side, it has an interior, six-pointed star-shaped structure, perhaps to help offset the shock of setback on lead pellets. The 12-gauge wad has four petals and measures 1-1/2 inches long.
There are two fundamental designs of plastic hull in use today: a two-piece, straight-sided hull and a one-piece, injection-molded, compression-formed hull. The straight hull has a removable base wad of paper or plastic that separates the powder from the metal of the base. This shell is typically the thinner of the two designs and is frequently the hull of choice for building powerful hunting loads where every micromillimeter is packed with powder and shot. PMC offers a straight-wall hull in its HP Competition load, however. These high-end target shells have a six-star fold and the hard shot contains 5-percent antimony.
The injection-molded or compression-formed hull uses an integral base wad, which is the wall itself tapering to the bottom toward the primer hole so that the thickening curvature of the hull itself is what separates the powder from the base metal. Winchester’s popular AA hulls are a good example of the more common compression-formed tapered hull. (They show a cut-away of the loaded hull in some of their recent advertising.) Typically, the thicker, injection-molded shells are the choice of hull for competition loads.
At the base of a straight-sided hull is the interior base wad. It is somewhat rare that this is a loose paper wad as in days past. Subjected to the intense flash of heat when the primer explodes and ignites the powder, a paper base wad can easily detach and fall out, deteriorate or blow into and stick inside the barrel. Reloading a hull without inspecting the fiber (or plastic, for that matter) base for adhesion is careless and unacceptable.
Today, many of these base wads are plastic and look like washers. Their functions are to separate the powder from the base, to elevate the powder to the top of the primer and to help seal the bottom of the shell. You do not want a gas leak anywhere, but it can be especially disturbing around the base of the hull.
By varying the thickness of the plastic base wad, a huge variety of load combinations is possible without mandating extreme measures in component adjustments. Instead of adjusting component height, ammunition manufacturers logically utilize various thickness base wads to facilitate many different load types. This allows them to get by with few part changes in the hull’s construction.
At the opposite end of the hull from the base is the crimp and no matter whether the hull is paper or plastic it needs to be positively crimped. One purpose of the crimp is to seal the end of the shell to prevent the shot from falling out and keep dirt from entering. The crimp holds everything in order inside the hull. It also keeps the powder and shot properly packed for that micro-second when the primer ignites the powder and pressure begins to build. The crimp is a patterned fold and it is essential for proper powder ignition and controlling the burn rate. Varying the depth of the crimp or otherwise changing a pre-established fold can quickly and surprisingly affect the pressure.
Beautiful, 6-fold factory crimps on Federal #6 12-gauge and #6 20-gauge shells, and a Wolf #8 12-gauge. You can build crimps just as good looking and, indeed, to be effective you must make this part of the reloading exercise a priority.
On many ranges, the rule is that if a shell hits the ground, it belongs to the range … and you can purchase your own shells from the club. This odd rule makes it tough on reloaders who shoot semi-automatics and pump guns, especially pumps like the Ithaca Model 37 High Grade that ejects hot shells straight down from the chamber, rather than out to the right or left side. For clay shooting, a double-barrel over/under with ejectors modified to hand extract shells might be easier on the back and give you cleaner shells to reload.
A few years ago, two types of crimps were common, the roll crimp and the star fold. The roll crimp dates from black powder days. Black powder was bulky, at least compared to today’s progressive powders, and it needed all the room it could get inside a shell. Everything was packed in tightly and a small over-shot card (also called a wad) topped off a roll-crimped load. The crimp rolled the hull firmly back on itself and down to the card, thus holding the powder and shot in place.
With the advent of more efficient smokeless powders, less length of hull was needed to contain the powder because less powder volume could accomplish the same or better results than black powder. Therefore, more hull was available for sealing the shell. The over-shot card could be dispensed with and the final quarter-inch of standardized paper or plastic shells was simply folded over toward the middle. Today’s final crimp depth is about 1/16-inch with either a six- or an eight-segment fold. Hevi-Shot shells were originally marketed with a roll-crimp, but with Remington’s partnership they have since switched to the more conventional eight-fold.
Is there a difference between the six- and eight-segment folds? Except for the number of leaves or folds, no, but it is believed that the eight-segment fold holds a little tighter and is therefore a little better for smaller shot, #7-1/2, #8 and #9 in target and small game loads. There is a tendency for the six-fold to be used with larger shot in hunting and field loads. The small shells used in the 28-gauge and the 410 use a six-fold. Although it seems counter-intuitive, the large shells of a 10-gauge also use a six-fold crimp, perhaps because they are heavy hunting loads.
The memory of a former crimp is not embedded in the plastic of a new hull, so it must develop a memory. Working this hull carefully into the crimp starter of your reloading press several times will introduce folds properly into the material. Often during handloading, you will be tempted to only tap the new hull into the crimp starter and move through this station rapidly. This is the wrong approach because crimp starting is vitally important to effective shooting. Impatient handloaders, after finishing such a load, occasionally discover that the closure in the center of the hull mouth is incomplete and that they have left a hole in the center where the crimp does not meet. Pellets can dribble out and this renders the ugly load functionally useless. This is a result of rushing through the crimping process.
Many experienced reloaders recommend that when you work with a new hull, consider using a six-point fold starter rather than an eight-point if you have a choice. The six-fold is easier to work and usually realigns easier.
INSPECT EVERY HULL
Because hulls are so important to successful shooting, you must inspect them carefully before you begin reloading. Sorting and inspecting hulls while you are sitting at the reloading bench can seem unnecessarily tedious, though: you are perched in front of your machine with your components and the power is on, but before you can load a single hull, you have to check the type, its integrity and cleanliness every time you set one up. Perhaps the best time to sort and inspect is while you are watching television. A golf, baseball or football game on the tube where action is intermittent, gives you the time and opportunity to check each shell. Then, when you sit down at your reloading bench, you can confidently pound out the reloads.
Initial sorting separates gauges and lengths. After that, you can sort for brand and type. Just because you are holding a 12-gauge hull does not mean that you can load it with just any 12-gauge recipe. Seemingly small but ballistically significant differences in hull material, design, capacity and wear affect loads profoundly.
Only factory loads are approved for competition at the highest levels, such as the FITASC