Most rifle loadings are all supersonic, so subsonic loads are specially down-loaded to stay below the speed of sound. In 9mm, most loading data are supersonic. All data in this caliber is subsonic but is not normally tagged with the name subsonic. Not all “subsonic” loads are noted as such in the data, because the cartridge is not capable of producing supersonic velocity. Subsonic loads refer to those whose velocity is less than the speed of sound. If the primer is above flush it can be run through the seating operation again to push it below flush. It is best to use your finger to test every primed shell case. As you gain experience in loading, the feel to accomplish this will become familiar. The ideal seating depth is just below flush. Sliding the index finger across the bottom of the primed shell case will quickly determine if the primer is above or below flush. The primer seating depth is best checked with your finger tip. This is especially true if you are using a handheld priming tool. Unless you are reloading on a progressive machine (each pull of the handle yields a loaded cartridge), the primer seating depth is controlled by feel as the primer is inserted. Seating above flush can also result in misfires. Seating the primer too high (above flush) can cause the cylinder to not rotate in revolvers, and can cause problems when the bolt slams home in semi-autos. Seating the primer too deep below flush can damage the internal components, leading to misfires and inconsistent ignition. You also need to be aware of primer seating depth when reloading. Primer seating depth – how far the primer is inserted into the shell case – is carefully controlled in factory ammunition. Hodgdon reloading data meets this requirement. Just remember, in shotshell reloading the reload data must be specific to the type of shot being used. A coffee cup of tungsten shot is heavier than all the others.A coffee cup of bismuth shot weighs less than a coffee cup of lead shot.A coffee cup of steel shot weighs less than a coffee cup of bismuth shot.To try to simplify shot density, think of it this way: Shot density affects how much room in the shell case the shot charge will take up. This is the primary reason that lead shot reloading data can never be used with any other type of shot. The hardest shot types are steel and tungsten. Softer shot produces lower pressure harder shot raises chamber pressure dramatically. Shot hardness has a direct effect on chamber pressure. The two characteristics of shot that change reloading data are shot hardness and density. However, in loading shotgun shells, this assumption cannot be further from the truth. It is easy to assume that all shot types can be reloaded similarly after all, they look the same – being round balls of metal. This data was created in the Hodgdon Ballistics Laboratory under controlled conditions, and only the top two loads show pressures that stay within the SAAMI industry standard of 11,500 psi. All shotshell reload data on the Hodgdon website has been created using an average crimp depth of 0.055″.Īs an example, here are ballistic test results of a standard 7/8-oz, 12-gauge load when crimp depths are varied Crimp Depth A crimp that is too tight (too deep) can increase ballistics more than what is expected from the reload data. If your reload crimp is too loose (not enough crimp depth), it will hurt ballistic uniformity. An example of the correct crimp is what is found on factory loads. This is one adjustment on a shotshell loading machine that is easy to overlook. Crimp depth of a finished shotshell reload is an important dimension to monitor for consistent ballistics and safe loads.
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