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Need guidance...case neck thickness
- Thread starter bgbuck153
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When fired, things change. Thickest part of neck wall vs thinnest part of neck wall can misalign projectile path. But again, don't forget there are a lot of guys shooting no-turn neck chambers with very good results.In a factory rifle the chambers neck is large enough in diameter that neck irregularities do not have any effect on bullet alignment in the throat.
And the Redding bushing die FAQ tells you if the neck thickness varies .002 or more to use the expander that comes with the bushing die.
I TOTALLY agree with your post. I have asked the question in a previous thread that I posted. It was suggested that I buy a couple of reloading manuals, I bought the suggested manuals and read everything from page to page; one manual was Reloading for Competition, Zediker. The manual is okay, I found the author to be a little more long winded than informative!! But he never writes about what stage your brass is supposed to be at/in before you start the process. From all of the literature I know how to turn cases and what tools to buy to get the process done, and what to use!! BUT.....where do you start from to begin with!!???? Do you start the process with a once fired case and ream the doughnut out then full length resize, do you full length resize the case, then trim it to length and then ream the case so you get the mandrel to fit properly, there's all this information, however no one tells you where to start, it seems like there's always something left out; start at "A", then go to "B", then to "C" and so on would be nice. I built precision plastic injection molds for six years, the molds had a .0005 thousandths flash point (means that all of the parts had to mesh and fit within .0005 thousandths). I know and understand machining processes, I just cannot find or figure out where one starts with case preparation. And....I've searched all the threads and forums here, there's not a starting reference point given anywhere. It's sort of like if you've never cooked an egg before, here's the egg and here's the frying pan and here's the stove, now go to it. If you've never ever cooked an egg before and you've never seen anyone else cook an egg, there are a number of blanks that ought to be filled in before the job gets done or even attempting to get the job done. There's a big difference between common-sense and common-knowledge. I've been reloading for 57 years, precision reloading is a whole new and different world to break in to. If someone reading this post knows of a manual that defines the turning process, the reaming process (as in A, B, C) from beginning to end, I really would appreciate that you let me know.
Hi sedancowboy, I am having the same difficulty trying to figure this question out (please read one of my earlier posts). I just searched that forum, it too doesn't address the OP's question. Thanks for your input and post, there all appreciated.
1) Take however many new brass cases you want to shoot.
2) Run them over the EXPANDER MANDREL to make the brass ID match the cutter post's OD.
3) Trim all to a UNIFORM LENGTH. Deburr in and out.
4) Lube the cutter, and start to adjust it for depth of cut and length of cut. (DO use a power tool: I would not try this by hand.) Don't try and take too much off in one pass. It will make a lot of heat in the tools, which will expand a tad, thereby making some brass thinner than others.
5) Assuming a factory chamber: Cut until ALMOST the entire circumference of the neck is shaved. You should have some 20% or so of untouched neck to be safe.
6) Having set your depth, now set the length. (Follow mfg's instructions). You want the cutter to just KISS the shoulder. (Donuts form when thick shoulder brass flows up into the now thinned neck after several firings). Keep the tool or the necks lubed unless you know what you are doing, and at this point, you don't.
7) Keep something cool handy to rest the cutter on to keep its temp as consistent as you can. Keep the cutter clean and run the tool SLOWLY.
8) Take some fine steel wool to the neck after you've cut it to smooth the cut.
9) Clean the lube off the inside of the neck, load and fire.
For more info try this:
https://www.accurateshooter.com/technical-articles/neck-turning-basics/
Hope that helped.
PS - I don't ream. It buggers the inside case neck with the tools I had, so I stopped.
2) Run them over the EXPANDER MANDREL to make the brass ID match the cutter post's OD.
3) Trim all to a UNIFORM LENGTH. Deburr in and out.
4) Lube the cutter, and start to adjust it for depth of cut and length of cut. (DO use a power tool: I would not try this by hand.) Don't try and take too much off in one pass. It will make a lot of heat in the tools, which will expand a tad, thereby making some brass thinner than others.
5) Assuming a factory chamber: Cut until ALMOST the entire circumference of the neck is shaved. You should have some 20% or so of untouched neck to be safe.
6) Having set your depth, now set the length. (Follow mfg's instructions). You want the cutter to just KISS the shoulder. (Donuts form when thick shoulder brass flows up into the now thinned neck after several firings). Keep the tool or the necks lubed unless you know what you are doing, and at this point, you don't.
7) Keep something cool handy to rest the cutter on to keep its temp as consistent as you can. Keep the cutter clean and run the tool SLOWLY.
8) Take some fine steel wool to the neck after you've cut it to smooth the cut.
9) Clean the lube off the inside of the neck, load and fire.
For more info try this:
https://www.accurateshooter.com/technical-articles/neck-turning-basics/
Hope that helped.
PS - I don't ream. It buggers the inside case neck with the tools I had, so I stopped.
bgbuck153
Well-Known Member
Thanks guys. I'll be getting started on this. Great info.
Alibiiv and the OP If I had fired brass that needed turning I would start by cleaning the brass and brushing the inside of the neck to clean it. I then would lube the inside of the neck. I spray Hornady one shot on a nylon neck brush and run it inside the neck. Next after removing the neck expander from my sizing die I would size the cases. Now to the outside turning process. You will need a expander die and expander mandrel ( I use Sinclair) a turning tool and a turning Mandrel with the appropriate cutter. Run all cases through the expander die to size the case neck to the exact dia needed for the turning mandrel. It is important to purchase both mandrels from the same manufacture. The expander mandrel is typically .001 larger than the turning mandrel. At this point you need to trim all cases to the exact length. This will ensure that the depth of each cut into the shoulder will be the same. Now follow the turning manufactures directions to set the turning tool up and turn a case and measure to see how you have done. You will ruin a few cases in learning how all this works. I suggest at first you only kiss the shoulder with your cutter. Tubing Calipers are a must. I use a power driver with shell holders from Sinclair to turn the cases and I hold the turning tool in my hand to let it float with the case being turned.
Turning case neck is not a cheap operation. you will have well over $300 in tools and a set of mandrels are about $60 for each caliber if you use a carbide turning mandrel. I recommend the carbide turning they are much less prone to galling and heat build up. I also use a small driver that turns slow and therefore have no heat issues at all. I do not recommend inside reaming unless you have to remove donuts to continue using the brass. If you use a feeler gauge to set up your cutter It is easier, use a .014 gauge and go from there. For a SAMMI chamber I would only turn your necks to skim about 80% of total area or .014 thickness. I would not turn necks thinner than about .013 unless for benchrest shooting tight neck guns.
If I have not answered all your questions then please continue to ask until I understand and then answer to your satisfaction. Remember there are no dumb questions only dumb answers from not understanding the question.
Henry
Turning case neck is not a cheap operation. you will have well over $300 in tools and a set of mandrels are about $60 for each caliber if you use a carbide turning mandrel. I recommend the carbide turning they are much less prone to galling and heat build up. I also use a small driver that turns slow and therefore have no heat issues at all. I do not recommend inside reaming unless you have to remove donuts to continue using the brass. If you use a feeler gauge to set up your cutter It is easier, use a .014 gauge and go from there. For a SAMMI chamber I would only turn your necks to skim about 80% of total area or .014 thickness. I would not turn necks thinner than about .013 unless for benchrest shooting tight neck guns.
If I have not answered all your questions then please continue to ask until I understand and then answer to your satisfaction. Remember there are no dumb questions only dumb answers from not understanding the question.
Henry
birdiemc
Well-Known Member
I have thoroughly read and re read the information in this entire thread. I also received some PM coaching from Dusty which was very helpful. I opted to try things out on my lathe, instead of purchasing expensive dedicated equipment. I followed Dusty's advice and took the expander out of my sizing die and measured how much my neck was being worked, surprisingly it was not that much. I then turned down a mandrel the exact size of my expander, which took a couple of tries. I ground a tool with the proper angle to allow me to just kiss the shoulder and I set my depth of cut to try and leave about 20% untouched. I still have not purchased a tubing micrometer to be able to measure neck thickness and concentricity, but by taking such a light cut and leaving a portion of the neck untouched I am comfortable with the process. Measuring with a .001 dial indicator I have less that .001 run out on my necks after turning indicating less than .001 variance in thickness. It has been fun, and I'm able to crank them out surprisingly quickly. Still havent had an opportunity to shoot and see what difference it all makes, but hopefully this week work and weather will cooperate. Been waiting on a new beam scale to arrive too. But just wanted to thank everybody who offered up so much useful advice.
DUSTY NOGGIN
Well-Known Member
the cut finish turned out amazing way better than my handheld does
I like what you are doing with the mandrel in the chuck of the lathe, it doesn't get an truer than that. What is the base of the case doing when you are turning the necks? Could you use a reverse center, or a sleeve that would fit in a drill chuck that the base slides in to hold the base concentric while you are turning the necks? Maybe I am getting a bit too finicky, the hand held turners certainly don't have anything supporting the base of the case while they are being turned.
That's a problem turning them on a lathe. I don't consider .001" thickness variation, after turning, acceptable. I rarely see more variation than that before turning.
If I turned the necks on my brass and ended up with .001" variation, I would consider it wasted time and effort.
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You're right about the .001 thousandths runout, curious if the case necks were cleaned prior to turning the outside? The method that he is using with the mandrel that has been turned in the lathe ought to give "O" runout though. I did have a question about supporting the base of the case while they were being turned. If the RPMs on the lathe are high, the base could whip and cause the runout that he is getting when he checks the case necks with a dial indicator. If the case neck is not concentric with the case body to begin, the case neck thickness could be the same if checked with micrometers, however that does not mean that the case necks are concentric with the case body and that would show up when checking the necks with a dial indicator. Hope this makes sense to you?
redleg1013
Well-Known Member
- Joined
- Jun 23, 2012
- Messages
- 243
But he didn't say he had a thou of runout, he said he had less than a thou of runout. If he's happy with his results why crap on them?
