I like the Redding 2400 Match Precision Case Trimmer (street price about $205)-though there are numerous models from different reloading manufacturers-for both its precision and ease of use. The user can adjust the setup to give a specified length the case mouth is trimmed when the user cranks the handle. The base of the case is held by a collet, and the case mouth is held against a cutter. There’s also a hand-cranked case trimmer, looking much like a conventional pencil sharpener. The length gauge is piloted through the case’s flash hole, so you get a nice, square cut. It requires a bit of elbow grease, though the unit can easily be adapted to an electric drill to make life easier. Among the simplest-and yet wonderfully effective-is the Lee Case Length Gauge and Trimmer (street price less than $25), which uses a cartridge-specific shell holder and a length/caliber-specific gauge, combined with a cutter to trim your case to proper SAAMI-approved case length. Looking at the tools available for trimming cases, you’ll see a diverse selection, from the simplest hand tools to motor-driven, micrometer-adjustable machines. Uniform case length equals a uniform roll crimp and that can make a big difference in pressures and velocity. This can be crucial with those cartridges destined for lever-action rifles with tubular magazines, as the bullet of one cartridge is pushed against the base of the cartridge in front of it and if that bullet isn’t properly crimped, you’ll see it move further into the case after being loaded several times. The same principle outlined above for the revolvers can be applied to the straight-walled rifle cases, as the bullets will need to be crimped in place to prevent them from either pulling out of the case mouth under recoil in the magazine or being pushed further into the case. But once you’ve got your cases trimmed to a uniform length, the roll crimp can be set to give the perfect amount of crimp to hold the projectiles with the same amount of force each time. As that die will be set in a stationary position, you can easily envision how a case that’s too short will give a very light crimp and how a case that’s too long will put an excess crimp, rolling the case mouth much too hard. That roll crimp is usually applied via a small shelf in the inside of the seating die. Revolver cases, on the other hand, definitely need to be trimmed to a uniform length, as they’ll use a roll crimp to keep the bullet firmly in place, more often than not. If I’ve used my pistol cases for a number of firings, I’ll often check the length to see if they need a quick trim. 40 S&W, 9mm Luger and their ilk to stretch to the point where the case length is too long for the chamber. While it doesn’t happen often, the potential is there to have the cases of the.
In most instances regarding the auto-loading cartridges, the case mouth is used for headspacing. Case Specificsįor the pistol cases, trimming is paramount. In many instances, that length will need to be trimmed to a uniform dimension. Our cases tend to see the brass flow from the base of the case toward the mouth, lengthening the case. However, over the course of multiple firings and resizing, brass will stretch. Our cases are made of brass for the malleable qualities of that metal it’s strong enough to handle the rigors of day-to-day handling, yet soft enough to be able to be reformed. Without trimming the cases, things can go awry, and trimming your cases is an important part of keeping things as uniform as possible. Bring fired cases back into spec for reloading, trimming cases can often seem like a chore.
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