A little neck turning story

[BoydAllen]

Today, a box of Norma 6PPC cases arrived. Anxious to try them out, I expanded them all, which was very easy, since they were only being opened up a few thousandths, and the new lube that Tod Kindler sent me worked well. It lubes really well, and dries so that you can drop powder into cases without having to clean out the lube. I really like that. Getting back to the turning, the Norma necks are softer than my Lapuas, and the fit on the turning mandrel was absolutely perfect. After I had turned a few necks, I tried to start one of the finished cases back on end of the turning mandrel, but the fit had tightened up considerably. I also noticed that the cut stopped short of the shoulder, even though I had trimmed all the cases to the same length, and set the mandrel in the tool so that the cutter would just touch the shoulder. About that time, I ran the jaws together on my dial calipers and noticed that the indicators did not zero. Evidently, when I had adjusted the tool to zero. I had not tightened the locking screw adequately. Hoping for the best, I rechecked my unturned cases, and found them to be uniformly shorter than I had thought that they were, BUT since I only trimmed to a couple of thousandths shorter than my shortest cases, even with the mistake, I was at a longer length than I intend to use for the final trim after turning. Close call, but I got lucky. While I was checking my unturned cases I remembered back to when I had learned that on this tool, when the cutter gets a little dull, that the necks are lengthened by the turning process, so I checked the six cases that I had just turned... by hand, to a nice looking finish, and uniform thickness measurement. The cases, had gotten from six to nine thousandths longer, than they started out before turning. So....early tomorrow morning, I am going to call K&M and order a cutter. I think that they are offering one in carbide now. Perhaps I will try one. In case you think that I am complaining about my tool, I am not. The only reason that I am posting this is to alert those of you who read it that you might want to compare your case lengths, before and after turning. Just so you don't think that I would leave the cases with the cut short of the shoulder, I should mention that I retrimmed the cases, and continued the cuts to the shoulders, making the cases correct. One little trick that I always use. particularly when turning necks by hand, is to pinch some 0000 steel wool around the case necks and turn the cases a few time to take off the minute ridges that remain after turning. I do this to get a more accurate thickness measurement, when I check the necks with my neck micrometer, that measures to .0001. It makes a difference.

 

[LongRanger]

Boyd, I had the same experience! The dull turning bit in my KnM turner was not only stretching the necks, it was thinning them. Called KnM but they were on vacation when I called earlier this month. I was able to sharpen mine with a diamond hone to get some new Norma brass finished until I could order a new one from KnM. When I finally got in touch with them I told them to send me 2 bits. "By the way" they said, "we are now offering carbide bits" so I told them to send me one and cancel the order for the 2 tool steel bits. Cost was under $40 including shipping.

Mannnn, the carbide bit cuts like a hot knife through butter, allowing me to get the job done faster, and neck stretch is way under .001. It does, however, still leave the ridges which remain after steel-wooling....while not "pretty" they still seal in the chamber perfectly when fired.

Neck turning is Almost fun now.

Another reason for steel-wooling after turning....about 10% of the last batch of Norma 7 RemMag brass I got had tiny bits of brass attached to the case body which I remove by running the wool down the case as it turns.

Frank B.

 

[timeout]

The carbide cutter is probably the way to go. I had trouble and called K&M, but he was uncertain if the carbide would do the trick. After placing a call to 21st Century, I wound up buying a their product. In speaking with John, it was evident he was familiar with the equipment and processes. I really like the fact that the 21st Century carbide cutters are ground for proper shoulder angles per whatever cal. cartridge case you are working on. This makes it easy to set for cutting right up to the shoulder and does a very nice job. I sprung for the lathe also and am sure not sorry. I am not knocking K&M. I am sure with the carbide cutter they do just fine. The 21st is more money, and buying the cutters for different calibers adds to the expense. For myself, I feel the extra cost was well worth it.

 

[GermanS1]

Boyd, thanks for sharing all that. I steel wool for the same reasons, hadn't thought to check length post-turning, will do that. Bruno's always has a huge K&M inventory, worth trying when you need something in a hurry. I'll have to get a carbide blade and try it. Thanks!

 

[Shynloco]

Boyd,
Its funny you mention your experiences with case growth after turning and trimming because the same thing happens to me here as of late. I'm using a Redding 2400 trimmer (has the micrometer adjuster) and as you know, I do the same mandrel regiment after FL sizing without the expander ball and then head over to the Redding Trimmer. My 6.5 is notorious for growth (even after two firings), however minut as it may be and after I trim to the set length (length set on the micrometer on the trimmer so they are uniform) I do the chamferring and steel wool thing on the neck and mouth of the casing and measure each piece of brass with the caliper only to find the casing will not pass through the jaws that are set and locked. So a second pass through the cutter has always cured the problem and after repeating the process, all my casings are within .0001 tolerance that is as close to uniform as I've been able to get them. Didn't realize it was the cutter that was getting dull so you've helped me out once again. Great to see this type of info passed around and makes me feel a little better that others are experiencing the same stuff in this effort for perfection and ultimate accuracy in case prep work.

Alex

 

[SS427]

I used a new K&M trimmer with a carbide cutter the other day on 100 Lapua cases. On the first pass the cases grew longer. They grew a little more on the final cut. I assumed that was normal.

 

[LHSmith]

To clarify, you guys are talking about K&M now making a carbide cutter............NOT the carbide cutter on the mandrel that is used to get rid of donuts?
Speaking about the carbide mandrel.....I have went back to the Plain H.S steel mandrel, because the carbide left nasty ridges inside the neck.....and my bullets are aways from the donut area.

 

[BoydAllen]

I used a diamond lap to dehorn the cutting edges on the end of my carbide mandrel...since then, no problems.