OzFclass

Hi all,

I have decided to give neck turning a go, in the interest of trying to get a consistent neck tension. I inside neck turn, to remove the donut, as I am using Lapua 6.5-284 brass, (Running a 284). Then using a K&M neck turner, I take the bare minimum off the thinnest neck, using this as my base line for all the brass to be turned.

So I should have all the cases with the same neck thickness, right? So why is it that 1 in 10 cases, after being run thru the bushing die have little to no neck tension for seating, where as the others are nice.

Could it be the "springiness" of the brass, with some being a little more "tired" than others. Would annealing perhaps be a tempory fix for this?

Cheers

Craig.

Once you have loaded up a bunch of ammo. Mic the outside of the neck of the loaded round.
Any variation in neck diameter could be due to the mandrel heating up and expanding while you are neck turning a bunch of brass. The result is necks of different thickness.
This will give variations in neck tension.
I neck turn a few cases using a battery drill, then put the cutting tool aside for a few minutes to cool.

Craig,
Hopefully you have a good micrometer , as well as a second one set up for measuring accurately the case neck thickness.
Does your micrometer show that the problem cases are springing back out to the original size after neck bushing ? Ie is the "problem" easily measured ?
How many total cases are you running at present ?
How many times have they been reloaded ?
What are the "maths" of your own chambering ?
I have neck turned over 500 6.5 x 284 cases now, necking them up for a 284 Win with a 0.313 neck.......so the "maths" in my own case are 284 + 013 + 013 = 310 for a loaded round. So with a 313 neck, that gives me 0.003 clearance on the neck with a loaded round, and using a 0.309 bushing gives me the 0.001 neck tension that I am looking for. I have measured many neck sized cases, and there is actually a variance from 0.3085 to 0.309.......... which I have always attributed to my own technique with the micrometer, but it seems that there definitely IS a variance in "springiness" with cases.
I annealed 200 original cases that had been fired 5 -6 times in my first barrel (using Wild Dogs Benchsource machine) and whereas before there was a big difference across the 200......where some had become very firm and you just knew that they had a lot more spring-back than others......now they are really nice to work with again. As good as new cases, literally.
I have thrown out a total of about 20 cases now (good for setting up a case trimmer) that just wouldn't hold a projectile consistently, even after trying a 0.308 bushing. They held a bullet, but returned to their bad habits straight away after firing. Almost half of these "sacked" cases actually measure 0.0125, which means that somehow during my neck turning, I have managed to take an extra 0.0005 off those cases.

Donuts. I was really worried about how I would handle these donuts that it seemed I was certain to get in my 284 cases. But after using my neck turning gear that Stuart Elliott set up for me initially, and showed me how to use it , I honestly haven't seen one yet. It seems that if you cut into the shoulder sufficiently when you neck turn, you don't get a donut. I have been expecting them to eventuate, but so far at least (6 firings) they haven't been visible. I have had one single case that the neck literally broke off on extraction after the first firing....so I obviously went too deep into the neck on that one when turning it initially.
I bought an inside reamer as well, but when one of our very experienced Forum contributors warned to to be very careful with it, unless I really knew what I was trying to achieve , then I put it back in the cupboard and haven't touched it since !
Tony

When neck turning cases with multiple firings, I believe annealing is essential before hand to soften the necks and allow them all to keep the die's neck dimension without spring back. Also to allow the shoulder bump to stay consistent so not too much is taken from one shoulder/neck junction over another.
I don't use bushing dies for FLS prior to neck turning as I'm not confident that the bushing mates with the shoulder 100% on sizing.
I anneal every firing for that reason, chasing consistency and quenching my OCD's thirst.

Regarding the mandrel getting warm and expanding. Stuart E suggested a few years ago, that after turning each case, while polishing the neck with steel wool, the mandrel should be laid to rest on cool piece of metal to allow some heat transfer and keep the mandrel temperature down. I put a little Imperial wax on the mandrel for every case too. Both Work well in keeping the mandrel temperature down.

I use the K&M hand held neck turner and expandrion die. After pushing the donut to the outside and cutting it off, I find that the inside cutter on the mandrel still picks up a little brass. Most likely the very back/inside of the shoulder.

On a side note.
My latest batch of Lapua brass has not been neck turned and I've left the "necking up donuts" alone. They get annealed every firing and I've only been neck sizing 2/3's. Its obviously not a match turn or a tight chamber and the donuts stay well away from the bullets. This brass is shooting just as well as my turned brass.

DenisA wrote:Regarding the mandrel getting warm and expanding. Stuart E suggested a few years ago, that after turning each case, while polishing the neck with steel wool, the mandrel should be laid to rest on cool piece of metal to allow some heat transfer and keep the mandrel temperature down. I put a little Imperial wax on the mandrel for every case too. Both Work well in keeping the mandrel temperature down.
.

Freezer/Chiller "Gel Pads" or even the hard plastic freezer "bricks" work really well for keeping the mandrel cool. Every time we buy "3 Germ Tick Fever Vaccine" to stop our weaner cattle dying of Redwater from cattle ticks, the DPI kindly sell us one of the gel type ! They are perfect for sitting the Neck Turning tool on between cases, especially if kept in the fridge and not the freezer.

Thanks for the replies guys.

I will definitely look at the annealing side. Perhaps do a test batch. I have 500 cases. I had them all sorted into 100 batch lots, as one batch of 100 was 3 firings older that the rest. But my 5 year old wanted to help one day, and well now I have 1 batch of 500.

I had never thought about the mandrel heating up. I don't use a electric drill to drive it, just old fashion hand power. Also, there is normally about a minutes rest between uses of the tool.

All food for thought.

But after using my neck turning gear that Stuart Elliott set up for me initially, and showed me how to use it , I honestly haven't seen one yet

Yeah someone knows how to turn necks properly
Eco I have never had donuts eighter one set of case I have has had 30 reloadings.
There are bibles of threads on this subject just turn your necks correctly in the first place.

Craig, IMO, turning necks with a cordless screwdriver is essential for maintaining sanity. I use an Ozito cordless screwdriver. It cost me $25 at Bunnings and its perfect as its max RPM is 200 which is apparently the ideal RPM for turning necks. Another factor in keeping mandrel heat down I guess.

Just from the OPs description, my guess would be the problem relates to varying neck thickness. As noted already, a MIC is needed to to check the variation of the turned cases. Unless you have a ball/tubing MIC, then measuring a loaded round with a regular micrometer (NOT a vernier!) is the best way to determine how consistent your turning efforts are.

In my opinion, and having tried both powered and hand powered turning, using a battery powered drill gives a smother and more consistent finish than turning by hand. Also, a carbide turning arbor is WAY better than a steel arbor.

Lastly, make sure you have a matching expander mandrel from the same manufacturer that made the neck turner. I had thought this was pretty apparent, but I recently bought a turner/expander set off a shooter, only to find the expander he was using was totally unsuitable for the turning arbor he was using, so I don't assume anything these days.