So I am reloading some 30-06 brass and the case trim length is listed at 2.484". My buddy says his tolerance when cutting to size is + or - .003". Do you have any particular tolerance you adhere to? I have a basic trimmer (no incorporated micrometer or dowel jigs to get the same length every time). What methods do you use for consistency/ease of trimming?
Case trim length tolerance
- Thread starter SD Mike
- Start date
Food for thought -
Case length is an important factor to control. If you have inconsistent case length, you will have inconsistent neck length, which leads to unpredictable neck tension. Consistent neck tension has a high degree of responsibility for contributing to accuracy.
With that said, cutting a case to length is only part of the success. Cutting the mouth of the case square is just as important and has just as much influence on neck tension.
The fact is, all of the case trimmers that "hold" the case from the base are less than helpful with cutting the case mouth square. This is a reality because brass cases are not concentric and will have a degree of wobble when held from the rear and guided with a pilot.
There are only two case trimmers on the market (readily available - not custom) that will successfully accomplish both tasks correctly and precisely. The L.E. Wilson and the Doyle Gracey. The reason they are so consistent is because of how these case trimmers contain the case and rest in a die on a set of parallel rails. This allows for consistent length cuts but also square case mouth cuts.
Basically the tolerances you are getting are typical due to the tool you are using.
Below is an L.E. Wilson containment die and the entire lathe as an example.
Case length is an important factor to control. If you have inconsistent case length, you will have inconsistent neck length, which leads to unpredictable neck tension. Consistent neck tension has a high degree of responsibility for contributing to accuracy.
With that said, cutting a case to length is only part of the success. Cutting the mouth of the case square is just as important and has just as much influence on neck tension.
The fact is, all of the case trimmers that "hold" the case from the base are less than helpful with cutting the case mouth square. This is a reality because brass cases are not concentric and will have a degree of wobble when held from the rear and guided with a pilot.
There are only two case trimmers on the market (readily available - not custom) that will successfully accomplish both tasks correctly and precisely. The L.E. Wilson and the Doyle Gracey. The reason they are so consistent is because of how these case trimmers contain the case and rest in a die on a set of parallel rails. This allows for consistent length cuts but also square case mouth cuts.
Basically the tolerances you are getting are typical due to the tool you are using.
Below is an L.E. Wilson containment die and the entire lathe as an example.
