I am new to reloading, and am hardly a professional researcher, but perhaps the test described below will shed some quantifiable light on the effect of an expander ball on brass.
The cases I used were Blackhills 223 Remington twice fired. The tools that were pertinent to the test include a Redding FL sizing die, optional carbide expander ball, Forster Co-Ax press, Imperial case lube, and Imperial media dry lube for neck interior. Wilson Sinclair case trimmer was also used.
All cases were trimmed to 1.750". Fire formed case neck diameter was .254" (average - some case neck thickness variation). Shoulders were bumped back a few thousandths. New set of three fire formed cases used for each test, except test #3.
Test #1 - FL resize w/expander using neck lube. Case lengthened by an average .005".
Test #2 - FL resize w/expander using NO neck lube. Case lengthened by an average of .005".
Test #3 - Trim brass from test #1 and #2 back to 1.750" and repeat test #1 and #2. Case lengthened by .001".
Test #4 - FL resize without expander ball. Case lengthened by .006".
At first, it appeared that the expander ball does drag on, and stretch the neck. But test #4 shows the case lengthens without it, perhaps due to the die forcing the brass having to go somewhere (up, into neck area).
Test #3 used already sized brass, AND it had an expander ball. Since no resizing is necessary, and if the resizing is actually causing the brass to lengthen, then one would expect no change in this test. In fact, the brass grew by just .001".
As an aside, the expander does work the neck. My fire formed brass measured about .254" on the neck. Without the expander ball, the neck is pushed down to .240", and the expander ball brings it back .246".
Is the expander ball a bad thing? To my mind, no, at least when it is carbide (which is MUCH smoother and easier than steel), but welcome other's perspectives.
- Phil
The cases I used were Blackhills 223 Remington twice fired. The tools that were pertinent to the test include a Redding FL sizing die, optional carbide expander ball, Forster Co-Ax press, Imperial case lube, and Imperial media dry lube for neck interior. Wilson Sinclair case trimmer was also used.
All cases were trimmed to 1.750". Fire formed case neck diameter was .254" (average - some case neck thickness variation). Shoulders were bumped back a few thousandths. New set of three fire formed cases used for each test, except test #3.
Test #1 - FL resize w/expander using neck lube. Case lengthened by an average .005".
Test #2 - FL resize w/expander using NO neck lube. Case lengthened by an average of .005".
Test #3 - Trim brass from test #1 and #2 back to 1.750" and repeat test #1 and #2. Case lengthened by .001".
Test #4 - FL resize without expander ball. Case lengthened by .006".
At first, it appeared that the expander ball does drag on, and stretch the neck. But test #4 shows the case lengthens without it, perhaps due to the die forcing the brass having to go somewhere (up, into neck area).
Test #3 used already sized brass, AND it had an expander ball. Since no resizing is necessary, and if the resizing is actually causing the brass to lengthen, then one would expect no change in this test. In fact, the brass grew by just .001".
As an aside, the expander does work the neck. My fire formed brass measured about .254" on the neck. Without the expander ball, the neck is pushed down to .240", and the expander ball brings it back .246".
Is the expander ball a bad thing? To my mind, no, at least when it is carbide (which is MUCH smoother and easier than steel), but welcome other's perspectives.
- Phil