Giraud Tool Company, Inc.
GIRAUD POWERED CASE TRIMMER
Page 3 of 10
holder. Rotating the case holder from one mark to another (45º) with move the
case holder approximately 0.009”
With some of your older or scrap RESIZED cartridge cases, trim a few cases to
check out the operation of your new trimmer. Insert a case into the shell holder
and press the case into the trimmer blade while the machine is running. If the
motor is bogged down or stops, the speed at which you inserted the case is too
fast. Gently but firmly will do, you don't have to jam it in there. As you press into
case holder, you will feel the vibration as the carbide blade removes material
from the case mouth, when it stops, simply twist the still inserted case with your
finger tips to even out the freshly cut surfaces.
Check the case mouth on your first case. You should see the case mouth bright
and shiny where the brass has been trimmed. If the case mouth is not uniformly
trimmed around the entire diameter, it is because the runout between the cutting
blade and case holder are just slightly out of alignment or the case neck is not
concentric with the case body. It only takes a thousandth or two to cause that.
But you can easily correct or overcome this by twisting the case a half turn or
more while the case is touching the rotating blade. As the case rotates and
blade rotates, the entire case mouth makes contact with the entire travel of the
blade. It sounds more complicated than it really is. Just give them a twist and
they come out pretty uniform.
Next, check your overall length of the
trimmed case with a caliper. I will set
the length fairly close, but it will really
depend on how you size your brass.
Since the case trimmer locates each
case by the case shoulder, if your
headspace dimensions on the resized
brass are not consistent, then the
case can't be trimmed to a uniform
dimension. I suggest the use of some
type of headspace measuring device
to monitor your resizing operation.
Several different brands of tools are
available from Stoney Point, Midway,
Neal Jones, Sinclair, and RCBS, just
to name a few. The simplest device
mounts to the jaw of your dial caliper and lets you measure the consistency of
each case quickly and easily.
Using the Trimmer
Trim and measure three cases. If your dimensions are /- 0.002" on the
overall length, you are in the ballpark. With a little use and consistent technique,
your cases should come out within 0.001" of each other, every time. If the overall
length you measured is the length you want the finished cases to be, you are
ready to trim some brass. If the length is too long or too short, loosen the jam nut
Figure 2 -
A properly trimmed case has a chamfer that is
even and smooth around the entire case mouth, both
inside and outside.
