Neck Thickness and Neck Uniformity

[bozo699]

Because of the looseness with which I hold the cordless drill and the tool, there is virtually nothing pushing the wrong way, and pushing the neck off of the mandrel and into the cutter takes some force toward misalignment. To me is sounds like you are trying to bench race this. Go turn and measure some necks. That is the best way. I have and can do what I have described. If you are asking if someone who lacks skill, experience, or is intentionally trying to have a problem can have a problem, the answer is yes. I am just reporting what I do, that has been accurately measured. Often, what we imagine or expect is not what actually happens. If engineers could visualize everything perfectly, there would be no need for test pilots. There are several approaches to turning necks. Choose the one that suits you. For me, the method that I have chosen is simple, direct, and produces excellent results. I should add that I generally have found that for manual tasks, that the written word loses something in the journey from the mind of the writer to the hands of the reader, and that I really prefer to teach these things in person for that reason. Perhaps it is my lack of communication skills. In any case, good luck with your neck turning.
Boyd

That's ridiculous!!....Your one of the best I know at explaining yourself. I understand why jlow would think the way he is about neck turning with a undersize mandrel, the problem is he has made up his mind your way won't work,...that is obvious to me. In this game of precision shooting and reloading one must keep a open mind and try new things or he/she will not advance in this precision game of shooting little groups. Boyd you shoot close range Br and I shoot LR BR but I have incorporated some of your short range ideas you have gave me to my LR needs and have advanced my shooting skill because of it, some day I might be able to give you a idea or piece of advice that might help your game some, I would like that for sure but one must listen with a open mind to learn. You keep right on explaining things, I enjoy your posts and usually always learn something while reading them
Wayne.

 

[jlow]

Actually, I have no doubt that BoydAllen’s method work in his hands, but as he said “I really prefer to teach these things in person”, and there is a good reason for this. The problem here is at least looking at just his descriptions (which is all we have); I do have doubts as to how it would work in my hands even though I am a very hands on guy (please read not one who just works with theory) because without a hands on working with him, all we have is a description which in my humble opinion, does not quite match up with the theory which appears flawed in the manner that I think I clearly stated.

I think you can bash me for daring to question someone who is very good at what he does, but somewhere in there, people should also be respected for willing to ask honest questions when something does not completely make sense even if the problem is only in the comprehension and not the actual method. Comprehension I would also like to point out is what helps all of us in a board like this, without which we would only know that someone can somehow do something but the question is how does that really help us.

 

[GermanS1]

Boyd, jlow:

I read Boyd's description of his method and it was very timely for me because I was having some trouble getting a consistent cut on some Lapua .30-06 brass. I turn the necks to 0.0125". Normally I use Lake City, Norma and Winchester and the Lapua, at roughly 0.015" is definitely thicker than those. Consequently, I was cutting about 0.0025" which is close to twice as much as with the others. Trying to do it in a single pass was giving me inconsistent results and I also found I was having to reset the blade fairly frequently, maybe that heavy a cut was wearing it or pushing it up.

All of this was with my K&M turner. I also have a 21st Century turner and the mandrel on that is slightly smaller. That's when the light bulb went on. Based on Boyd's post, I set the 21st Century cutter to 0.0132" and expanded the case once on the K&M expander which is slightly larger than the 21C. The resulting fit was not as tight as with the K&M cutter, but still completely wobble-free. Let's call it a smaller interference fit. I then made the cut to 0.0132", removed the case, expanded it twice on the K&M expander, then cut it to 0.0125" with the K&M cutter.

The result was perfect 0.01250" all around. I followed with 30 more cases and had equal results with no more blade adjustments or variance around the necks. Most of the improvement is likely due to cutting in two steps for such a heavy cut, of course, but the manner in which it was done is important too. By using the slightly looser fit on the first cut, heat buildup on the case neck was minimized. I might add that the dimensions from that first cut were also very consistent, although I didn't check each case at three points as I do after the final cut.

Boyd, great tip, I might have adapted it a bit for my purposes, but without it I wouldn't have thought to use the smaller 21C cutter with the K&M expander at all. Live and learn!

 

[BoydAllen]

;D

 

[bozo699]

Actually, I have no doubt that BoydAllen’s method work in his hands, but as he said “I really prefer to teach these things in person”, and there is a good reason for this. The problem here is at least looking at just his descriptions (which is all we have); I do have doubts as to how it would work in my hands even though I am a very hands on guy (please read not one who just works with theory) because without a hands on working with him, all we have is a description which in my humble opinion, does not quite match up with the theory which appears flawed in the manner that I think I clearly stated.

I think you can bash me for daring to question someone who is very good at what he does, but somewhere in there, people should also be respected for willing to ask honest questions when something does not completely make sense even if the problem is only in the comprehension and not the actual method. Comprehension I would also like to point out is what helps all of us in a board like this, without which we would only know that someone can somehow do something but the question is how does that really help us.

jlow,
I wasn't bashing you at all my friend, just my observations and opinions as a outsider looking in, if I miss read it then I apologize but I will stand by what I said,.....We must be willing to try new things or we will not and cannot advance! So with that being said grab some range brass or some brass that is on it's last legs anyway and try with a open mind Boyds method, you may be pleasantly surprised then again you may have to modify it as German did to make it work for you and then again it may not work at all for you although I would imagine it would but if not try another method altogether. I personally use two cutters if I have to remove much material, right now for my immediate br rifles I am using new blue box Lapua 6br brass which measures about .0125 I take about .0005 off then fire form to 6brx then inside ream which gives me about .0015 per side or .003 total neck clearance which is where I want to be, I then fire it again as I am working up a load for the rifle and I run the inside ream in it one more time it usually just kisses the neck in a few places and my new 100 pieces of fireformed brass will last the life of the barrel and it is virtually perfect. Some say if you turn first before firing you will get a donut,...I have not seen that I turn it long so it goes past the neck shoulder junction when it is formed then inside ream anyway but if it did develope a donut it wouldn't matter my bullet would never see it.

However I have such a appetite for learning new things and Boyd has never steered me in the wrong direction I am going to grab some old brass and give it a try, if I don't have any luck doing it I will call him and have him explain it to me in a way I can understand, if it still doesn't work and I am tired of playing with it I will simply abandon it and move on, I hope you get it figured out jlow and once again no bashing was intended but as Boyd pointed out it must be my lack of communication skills have a great day
Wayne.

 

[jlow]

Hi German,

Thanks for writing in with additional details – a big fan of course of your online journals as I learned a lot from you.

I want both you and BoydAllen to know that I appreciate your effort and time to help me understand this interesting technique. I have just spent a bit of time re-reading the posts. It appears that one of the problems of neck turning relates to the heat generated as a result of the tightness of the fit of the brass on turning mandrel due to inadequate sizing by the expanding mandrel and perhaps also by the speed of turning used by some especially when the required cut is significant.

It looks like what my misunderstanding is that I did not appreciate the fact that both of you are using two completely different sets of expander mandrel and cutter therefore reducing the amount of cut when each is used – that to me makes good sense. I had at first thought that BoydAllen was using one single cutter but two different expanding mandrel – thus the concern as it relates to looseness of fit.

I know that my questions sometimes comes across as relentless and un-accepting. What I have learned in the few years I have been alive is that when there is something like this that you don’t understand, there is usually something good in there. The best course of action is not to retreat or to just follow the recipe. Understanding why something works is the key to success – thus the questions.

Bozo699 – not offended but just wanted to correct your comment that “has made up his mind your way won’t work”. It is of course exactly the opposite. If I think something will not work, I usually shut up as I usually don’t find long debate about nothing rewarding. In this specific case, I was sure that there was a gem in there and want to find out what it was.

 

[BoydAllen]

The reason that I have used two different tools is so that I have them, and it saves having to reset to the same ten thousandth for the final cut. If you are careful, you can turn very good necks with a slide on fit, but you have to use very specific technique. The keys are that the tool and and case be allowed to wiggle as they "want to", and that the cutter is cutting the entire time that it is on the neck, which keeps the neck tightly pinned to the mandrel on the cutting side. This is the point of moving down the neck quickly to the shoulder, intentionally leaving material to be removed on the slow trip back to the case mouth. If you go to the shoulder slowly, there is not enough pressure on the neck on the way back to keep things where they need to be. I got the idea for this fast slow thing from an article by Dick Wright. The part about its allowing a looser turning mandrel fit came from me, and observations that I made, particularly after getting a good neck mic.

The reason that this "freedom to wiggle issue is so important, when making 6PPC cases, is that no matter how careful you are, expanding the .220 Russian necks up to 6mm causes them to become more misaligned with the case body. The unexpanded necks have a TIR of around .002. About the best that you can get after expanding is .004, and often it is more. This "kink" in the cases is largely responsible for their wobbly motion while being turned.

On the other hand, if I use the pistol powder/NO BULLET method, or rough turn at .22 caliber and then either use that method or fire a .22 BT in my 6PPC fire forming barrel WITH A NORMAL PPC POWDWER ...NOT PISTOL POWDER!!! The cases are a lot straighter for their final turning and first firing after fire forming.

 

[jlow]

Thanks! That clarifies the other question I have regarding the technique of “moving down the neck quickly” and leaving material to be removed on the slow trip back to the case mouth. I would assume then that you never make more than one trip up and down the neck?

 

[BoydAllen]

You are correct. After you have turned your necks, while they are still in the holder for the cordless tool, you can trim with one of the Possum Hollow tools (if one is available in your caliber, chamfer (VLD) and then spin the neck in a wad of 0000 steel wool, and finish by pushing the end of the neck (while it is being spun) hard into the wad of steel wool that you are holding so that bulges into the case mouth an polishes the the chamfer, as well as taking any burs off of the outside corner of the case mouth. Try it, you might like it, and the first bullets that you seat will appreciate it.

 

[jlow]

Hmmm… Thanks a lot. I do as a rule, chamfer and debur but never thought that the chamfer may need polishing. Will get that 0000 steel wool and give it a go!

 

[bozo699]

You are correct. After you have turned your necks, while they are still in the holder for the cordless tool, you can trim with one of the Possum Hollow tools (if one is available in your caliber, chamfer (VLD) and then spin the neck in a wad of 0000 steel wool, and finish by pushing the end of the neck (while it is being spun) hard into the wad of steel wool that you are holding so that bulges into the case mouth an polishes the the chamfer, as well as taking any burs off of the outside corner of the case mouth. Try it, you might like it, and the first bullets that you seat will appreciate it.

I tried this method of yours in my last match and did the best I have ever done! Thanks
Wayne.

 

[coues52]

1+ great timely article..I just received my new 284 and I thought i had some reamer problems..the builder showed me it is a brass problem,(inside donut formed at my champher upon firing, on top) my winchester necks run .014-.015 with my .3175 neck and I may need to do a lite skim cut to make my .004 clearance (total blow out) with my .311 FL Forester die..looks like I,ll be giving John at 21st century a call..~Danny