How Not to Seat Bullets



Spring has sprung here in Michigan.  The maple trees have blossomed and few ever notice.

Maple Blossoms

The inspirational spring air may have influenced my Copper Blossoms.


How Not to Seat Bullets

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.


Scratched Bullet

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.


Rough Dynamic Bullet Seating Chart

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.


Normal Bullet Seating Chart

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.


First Trimming Station

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.

Second Trimming Station

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.


New 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



Rifle Silhouette Shooting

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Released - May 13, 2006
Revised - June 23, 2006