The Perfect outside Case Neck Chamfering Tool

Perfect Neck Chamfering Tool

For many years now, I have been using either my Pacific or RCBS made by L. E. Wilson case neck chamfering or case neck de-burring tool. I have never been that impressed with them.  The little fins on the base of the tool used to chamfer the outside of the case neck were almost impossible to sharpen.  My tools would also not hold an edge after sharpening.  Recently I became aware that I was actually rolling the month over some while I was chamfering the outside of the case neck.  Click here, for full story on “How Not to Seat Bullets”. This little incident really got me discussed with my chamfering tools.  I started to think of ways to improve them.  My first attempt at savaging one of my little chamfering tools involved making only one fin do the cutting and let the other two just be locators. I rounded and polished two of the fins and sharpened the third fin like the edge on a knife. I thought that perhaps a scrapping action to remove and smooth the rough edge on the outside of the case neck would be better than a normal cutting tool shaped edge.

Tool will not stay sharp

After many sharpening attempts, I finally got the one fin with a nice knife like sharp edge.  This new arrangement seems to work okay and I began to get acceptable chamfering results.  However, the tool would not hold the edge or stay sharp.  The brass case necks were also scoring my rounded and polished locator fins after only doing one hundred 223 cases.

Case wears on rounded guide

At first, I was thinking about the little ceramic knife sharpening stones.  I did not think a ceramic type stone would be tough enough or cut well enough for case neck chamfering.  Next, I started to look through my Production Tool Supply Catalog for a carbine or high speed steel cutter that some how I could adapt for this chamfering process.  What I now though might work was a pocket or pin sized Knife Sharpening steel.  Just like the large knife steel files with the file teeth running the length of the round file.  I saw something like that on the internet, so I am off to one of the local Outdoors stores.  After a little looking, there it was, “The Edgemaker Pro Knife Sharpener”.

The Edgemaker Pro has two sets of crossed little steels.  One set had the file type cut edges and the other was smoother with some type of diamond coating.  The little knife steels were .182 inch in diameter and 2 inches long.  These were just what I was looking for.

New Tool and & Old Tool

My Pacific and L. E. Wilson tools were 5/8 inches in diameter so I want my improvised tool the same diameter so it would fit the same hole in my trimming station.  I have some 3/32 in diameter harden steel rod to use as the locator pins.  Therefore, I drilled three holes, 120 degrees apart, on one the end of a small piece of 5/8 inch aluminum rod.  Two of the holes, .092-inch diameter for the locator pins, were .146 inches from the centerline and the other hole for the small knife steel file, .182-inch diameter, was .191 inches from the centerline.  I drilled all the holes at an angle of 15 degrees from the centerline of the rod.  I tried 10 degrees first, however that angle was too small and you could chamfer the case shoulder and the case mouth at the same time.  I drilled the large hole, which the file fits into deep enough that only half of the file sticks out.  I also drill the other smaller holes for the locator pins until they penetrated the larger hole.  I even added a small setscrew to hold the knife steel in place.  This also allows rotating the file and exposing a new cutting edge.  I used Red Loctite 742 to hold the small locating pins in place.

Knife Steel Cutter

Initial testing indicates that the little knife steel file works great as a chamfering cutter.  The file makes a nice clean cut on the brass.  If I make other one, I may add a 60 or 80 thousandth hole in the center.  A short piece of harden steel rod could then be inserted into the hole and help center the case when using by hand off my trimming station.  K&M’s new taper case mouth reamer now has this feature.  Now I think I have solved my case chamfer issues.

Now if I can get K&M to make this outside neck chamfering tool to complement their outstanding tapered neck reamer.

Here is some of my dynamic bullet seating force results, which got me, started on this quest in the first place:

Data summary for 223 Winchester brass seating 80 Sierra bullets:

I load in 100 round batches using MTM 100 round boxes.  I started out with 1000 pieces of new Winchester brass and prepared all 1000 of them the same. During the preparation I culled and few cases out and then I sorted by weight.  Using the Lightest 100 of final best 800 in box one, next 100 in box two, etc.  So I have eight boxes of one hundred 223 cases that have been all prepared the same.  Box one after the initial firing, has only been reloaded using a .242 neck bushing.  Box two with only a .243 neck bushing.

Box One:

I have loaded six times, using a 242 neck bushing each time when resizing cases using Redding Type S full sizing die.  First load data is what the brass was at after all the case preparation, which included neck turning.  The neck walls thickness ended up around .011 inches.  Turned necks would just fit into the 244 bushing.

Load Force 200 Data:


1st Load
2nd Load
3rd Load
4th Load
5th Load
6th Load**
Seating
Force (lb.)
Not Recorded
61.19 lb.
42.15 lb.
39.88 lb.
38.96 lb.
41.45 lb.
Standard
Deviation
Not Recorded
7.48 lb.
5.63 lb.
4.98 lb.
4.80 lb.
5.97 lb.

**Load Force 250 Data - I had my 200 unit upgraded to newer 250 model.  New unit might be reading higher.

Seems like bullet seating force decreases slightly for each reload and increases in uniformity.

Box Two:
Loaded six times, used the 243 bushing each time when resizing cases using Redding Type S full sizing die with bushing.

Load Force 200 Data:


1st Load
2nd Load
3rd Load
4th Load
5th Load
6th Load##
Seating
Force (lb.)
51.8 lb.
36.9 lb.
30.9 lb.
27.3 lb.
32.2 lb.
15.1 lb.
Standard
Deviation
9.89 lb.
5.38 lb.
4.95 lb.
4.49 lb.
9.67 lb.
3.96 lb.

## Load Force 250 Data - I had my unit upgraded to the newer 250 model. New unit might be reading higher.

Seems like bullet seating force decreases slightly for each reload and gets more uniform like box one but at lower seating forces using a larger neck sizing bushing.

I started using my new trimming station, which reversed the case neck chamfering and reaming operations.  I also used my modified Pacific chamfering tool with only one sharpened fin.  Note the difference with the 6th Load in the above table for Box 2. More on the 6th load later.

Box Three:

Loaded only two times so far, used the 243 bushing each time when resizing cases using Redding Type S full sizing die with bushing.

Load Force 250 Data:


1st Load
2nd Load
3rd Load
4th Load
5th Load
6th Load
Seating
Force (lb.)
58.87 lb.
16.40 lb.
.



Standard
Deviation
12.95 lb.
4.79 lb.
.




My new Load Force 250 may read a little higher than the older Load Force 200. However, box three is statistically similar to box two for the first load.

Second load:

Average Dynamic Bullet Seating Force = 16.40 lbs.

SD = 4.79 lbs.

Wow some difference, between the first and second load, not like Box 1 or Box 2 first, and second loads.

Second load on Box 3, I also used my new trimming station, which reversed the neck outside chamfering and the inside case neck reaming operations.  I also used the newly sharpened Pacific tool, which I rounded off and polished two of the three fins.  I only sharpened one of the fins.  I sharpened that fin edge like a knife, not like a tool bit.  Could that change make that much difference?

The same thing showed up on load six of box two after using my new trimming station and sharpened Pacific tool.  I am also being very careful not to force case on the tool doing the outside chamfering operation.

Interesting data:  This is why I have been pursuing a better outside case neck chamfering tool.  Only time and more reloading will tell.  However, it goes, I think I have a better outside case neck chamfering tool and hopefully no more copper blossoms.  I now have to go shoot some so I can reload and see what happens.  Has far as shooting box one, two, and three at 600 yards with different neck tensions, I have switched boxes during target strings and have not seen any difference in score or elevation.

New Trim Station

Since seeing something funny here with my 223 cases, I have run all my new 6XC cases across my trimming station one more time to try my new chamfering tool and re-ream the neck with the reamer at its latest setting.  I set the stops on the K&M tapered neck reamer so I can feel a 244 Gage Pin fit or start inside the neck.  This is something I also did for my 223 case.  Set the stop on the reamer so a 224 Gage pin would just fit or start in the neck.  I have concluded after playing around with my Load Force 250, that the chamfered neck opening should be ever so slightly larger than the bullet diameter.  I really like the K&M tapered neck reamer.  However, it does have one drawn back.  Like any good seating die, you must have one for each caliber you are loading.  I now have three so I may leave them set at the depth of cut I want for each caliber.

The little Edgemaker knife steel used for the case neck-chamfering cut seems to be holding up very well, after doing close to eight hundred cases so far.  The little knife steel seems to be as sharp as it was when new and no brass buildup in the file teeth.  The chamfer on the case neck is clean and sharp.

Larry Medler
anyrange@comcast.net


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Released -August 3, 2006
Revised - Augsut 4, 2006