Quote:
Originally Posted by Duramaximos
Hello,
I have a process question. For those of you that outside neck turn your brass, do you do so before or after sizing?
Also, I've been cutting only enough material to uniform the neck wall thickness, but wondering if there is an optimal neck wall thickness for best accuracy? In other words, assuming the neck walls have been turned, is a thicker neck wall more accurate than a thin neck wall, or vice versa?
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I've found it helpful to ensure the neck has been resized prior to expanding it over the expand mandrel for the turner. That way you can be sure the neck starts at a point
smaller than the expand mandrel. How much smaller really isn't overly important - you're just making sure that the necks aren't larger than the expand mandrel. This is key, as the inside of the neck references off of the pilot.
The main factor to the answer of the next part depends on why you're cutting the necks. If you have custom-reamed chamber that's tight, you'll need to cut them down to fit. If you have a SAAMI chamber and you're turning necks to uniform neck tension, the exact amount you cut away doesn't overly matter. Numbers vary, but the most common recommendation I've seen is to trim away enough material so that about 75% of your necks have had material trimmed away from about 75% of their surfaces. Here, you're trying to reduce the difference between the thickest parts from the thinnest parts. Uniforming neck thickness is one of the fundamentals in uniforming neck tension. Uniformity in neck tension is one of the fundamentals in achieving tight groups.