How
Not to Seat Bullets
Spring
has sprung here in Michigan. The maple trees have blossomed and
few ever notice.
The inspirational spring air may have influenced my Copper Blossoms.
More properly put "How Not to Seat Bullets". Pictured above is an
80 grain Sierra MatchKing in full blossom after being stuck into one of
my Winchester 223 cases.
Above picture is the blossomed bullet pulled from the case. The
last one hundred rounds I loaded had a few of those blossomed
bullets. Normally this may go unnoticed for me; however, I was
measuring the dynamic bullet seating forces, which made me more aware
of any differences.
The above chart shows the dynamic bullet seating force for the
previously pictured blossomed bullet. Note the large initial
force used to cut and scratch the bullet outer surfaces. The
final seating force of 47 pounds is just before the Wilson Straight
Seating Die bottoms out and the force on the load cell jumps.
The above is more representative of a normal dynamic seating force when
seating an 80 grain Sierra MatchKing into a 223 case. Note the
initial raise in force needed to get pressure ring on the boat tail of
the bullet to start moving and entering the case. Then the
dynamic seating force drops and then begins to build back up as more of
the bullet’s surface area is contacting the case neck. The
80 grain Sierra MatchKings are so long that the shoulder on the boat
tail passes completely through the case neck. You can see a
slight drop in the dynamic force has the boat tail passes through the
case neck before the Wilson Straight Seating Die bottoms out and the
force jumps. The chart also indicates that no donut is lurking
around inside this case neck. If a donut was present, the dynamic
force should increase in a matter that would be visible on the graph
just before the dynamic seating force jumps when the Wilson seating die
bottoms out. Actually, the donuts may be easier to chart using a
standard reloading press instead of an arbor press. Time will
tell and that one, Wilson does not yet make a die for the 6XC
cartridge. I will be looking a 6XC bullet seating forces shortly.
Measuring the
dynamic bullet seating force made me more aware of things. In the
past, every now and then, I would notice some copper shavings on my
reloading press after seating bullets. However, this copper
blossom really got my attention while using my Load Force 250.
The Load Force 250
is a measuring instrument that measures the bullet
dynamic seating force in pounds and displays the results on a computer
screen. After seeing a few of these funny looking charts or
graphs, I started to review my case preparation process more
closely. I have been trimming my cases using a three stage
trimming station and a cordless electric screwdriver for several years
now.
I have even
updated my original Powered
Trimming Station
that used the Skil 180 rpm cordless screwdriver to one that uses a
DeWalt 400 rpm cordless screwdriver. I have also epoxy glue
little wooden wheels on my Sinclair case holders easier tightening and
loosening.
I would trim the length, debur the inside of the case neck, and then
debur the outside of the case neck. I use the Lee trim gauges and
cutters to trim to length. For the inside deburring I have been
using the K&M taper reamer which is like very much. For the
outside neck deburring I have been using one of those rocket shaped
deburring tools. I have two of them and one worked better than
the other one. I made a new trimming station to fit my new DeWalt
cordless screwdriver and I could not remember which of the two rockets
worked the best. I also could not tell any difference in the two
using my new DeWalt cordless screwdriver. Neither of the two
rocket cutters seemed to work very well.
Therefore, after
seeing ugly the dynamic bullet seating force charts, feeling the extra
effort to seat some bullets, and then pulling one of those blossomed
bullet only to discover that I had rolled the case mouth rim inward
while deburring the outer edge. When deburring the case mouth on
the outside edge, every now and then I could hear some tool
chatter. This little chatter really shows in the picture. I
decided that as a quick fix to reverse the neck deburring
operations. That is to do the outside first and then do the
inside of the case neck. Da, makes sense. That required a
change in my trimming station to keep things in order. That is
right to left processing steps and not back and forth steps using the
trimming station. A new trimming station was much to easier make,
then trying to bust apart the glued construction on my current trimming
station.
My new trimming station also included a couple of upgrades. One
upgrade is the little round wooden balls that eliminated the need for a
wrench to change tools when changing calibers. I have also been
modifying and sharpening my rocket deburring tool. I rounded off
two of the three fins so they are just guides and not cutters. I
have been stoning or sharpening the third fin. This has helped
and I have the little rocket working much better now. I am still
going to be looking for an improved method to debur the outside surface.
The bottom line
is still outside debur first and then inside. In addition, I now
make sure my K&M 7 degree tapered reamer is set so the inside
diameter of the chamfered edge on top of the case neck is slightly
larger than the bullet diameter. This I check using a pin gage
one thousand larger than bullet diameter. The first batch of 223
ammo loaded after using the new trimming station were great. All
of the dynamic graphs were smooth and very similar to each other.
That box of ammo also shot great (200-15X) at 600 yards.
Larry Medler
anyrange@comcast.net
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Released -
May 13, 2006
Revised - June 23, 2006
