Turning case neck ?

[06shooter]

Is this a must for a factory chamber and hunting ?
How bad are the groups if you don't ?

[Snyper]

It's almost never required unless you have a very tight chamber neck, and are using cases that have been formed from another cartridge.

I've never turned a neck and I started reloading in the early 80's

[math teacher]

Slip a bullet for the cartridge you are shooting into the neck of a fired case. If it goes easily, you are good to go for hunting. Otherwise neck turning is for precision target shooting and perhaps for those who insist on shooting animals at super long range.

[4runnerman]

Mathteacher hit on most of it. A lot will go on your Brass you buy. Most time Lapua and Norma Brass will not need it done. Also as mathteachr said- It is a task if you are into long range shooting with extream accuracy. Or if you are just into going all the way. So many other aspects of reloading are needed to really notice the difference.

[NoSecondBest]

I have all the stuff sitting here to do it because I used to do it. I've never found any problems with factory brass that actually needed it done. In fact, I never noticed a significant difference in accuracy when comparing brass having this done and not having it done. Leave it to the bench rest shooters.

[06shooter]

Thanks guys , that's one step I don't have to worry about !

[Mike / Tx]

Quite a few years back before I became rich and beautiful, well rich enough anyway, to afford to buy plenty of brass in bulk, I had issues with my .243 and 25-06 after getting up to around 6-8 loads on the cases.

As mentioned above the bullets would hardly go back into the fired cases. It was causing several issues for me the least of which was consistent accuracy.

I endedup borrowing a trim set form a neighbor who had one and after trimming up the necks everything was hunky dory again.

As to hte necessity of doing so, not really an absolute unless your using something on the high end of loads which is pushing the brass into the necks. That was my issue to begin with and having worked up different loads with new cases, and not those which had been loaded half a dozen or more times, things are far better. Most of my cases back then were either my own once fired or range pick ups or even necked down form 30-06 or 308's.

[NoSecondBest]

I endedup borrowing a trim set form a neighbor who had one and after trimming up the necks everything was hunky dory again.

Mike, I think the OP was referring to turning case necks, not trimming them. He may be already trimming them, he didn't say whether or not he was. I think most reloaders trim. If not, they will after a while when the brass gets too long.

[06shooter]

I'm not reloading yet , I'm doing a whole lot of studying right now before I buy a press etc......

[Snyper]

Yes, "trimming" and "turning" are totally different operations

Trimming changes length only, while turning changes neck diameter (outside turning) and brass thickness at the neck (inside AND outside turning)

[KEYBEAR]

I have a 223 bench gun I shoot a lot with a very tight chamber all brass are turned . You will find most brass is not round and it can be a benefit to turn all new rifle brass .

[06shooter]

I have a Weatherby vanguard s2 3006, I don't know weather it's tight or not.
I thinking about starting out with new brass that's already prep and just reload them.

[Mike / Tx]

Yea I made a mistake in my term, meant neck "turning" set all the way. I had three grandkids running through the house at the time getting ready to head OUTSIDE if you know what I mean...

[Nathan]

Generally, I would avoid neck turning. It is the kind of thing you do when your gun shoots .5" at 100yd groups and you wants .4....

[Bart B.]

What does turning case necks do?

First off, it makes the wall thickness uniform if the neck's cleaned up all the way around.

What does that do?

It centers the bullet in the case neck. How well the bullet centers in the chamber is controlled by how well centered the case neck is on the case shoulder; for cases headspacing on their shoulder. As the case neck doesn't touch the chamber neck until after the bullet's left the case, that part's meaningless. So it does nothing to center the case neck in the chamber neck. It also may uniform the neck's grip on the bullet so the release force to get the bullet moving out of the neck is more uniform. One has to measure that release force to get meaningful data.

Do bullets centered in case necks improve accuracy?

That depends on all sorts of things. A case neck with a wall thickness spread of .002" has its bullet axis .001" off the outside neck wall axis. Turning the neck to clean that up makes wall thickness spread zero and the bullet axis will be centered on the neck outside neck wall axis. Now, there's more clearance between the loaded case neck and the chamber neck; case necks do nothing to center bullets in chambers but it's a popular myth that they do. The difference between bullet centering in the chamber is only .001"; assuming both instances had zero bullet runout; the round's perfectly straight and the bullet long axis is aligned with the case axis. If bullet runout on the neck-turned case is .001", what have you gained by turning the neck to uniform thickness? What if unifomed case necks are bent by an expander ball coming up through them on the way out of the case?

Sierra Bullets learned in the 1950's that their match grade test barrels with SAAMI spec chambers in rail guns shooting the best match bullets made would shoot sub 2/10ths inch/MOA 10-shot groups in their 100-yard indoor test range; often down in the 1/10th range. Didn't matter whether case necks were turned and uniformed or had a .001" to .002" wall thickness spread. They quit turning case necks. They also do no other case prep whatsoever and still get 1/4 MOA or better 10-shot test groups in their 200 yard indoor range with their best match bullets. Sierra full length sizes all their test cases in Redding dies; bushing ones without expander balls if made for their test cases otherwise standard ones with expander balls.

I tried neck turning; gave up as I saw no difference in accuracy through 1000 yards.

By all means, if turning case necks makes you feel or shoot better, do it

[cdoc42]

I agree. I was turning case necks 20 years ago and quit because I couldn't discern any increase in accuracy. Every now and then I think about it again when I seat bullets and feel some degree of resistance, then measure the OAL to the ogive and find the "hard" seat bullet is 0.002" different than my planned seat depth. For the routine fun target practice and hunting that I do, I won't lose any sleep over it.

[math teacher]

I mentioned earlier to insert a bullet into the neck of a fired case to see if it enters easily. What if it doesn't. Bench rest shooters will cringe at this, but what I do is chuck a slightly smaller bit in a drill press and run at slow speed. A coulpe of passes of the case over the running bit usually does the job, and the results seem to work just fine.

[06shooter]

Mathteacher, so this doesn't hurt accuracy ?

[math teacher]

Mathteacher, so this doesn't hurt accuracy ?

No, they shoot the same as the cases that have not had this done to them. I do not press the case against the bit in one spot, but rather spread it around the neck.You are not removing much metal. Still this is not a procedure I would recommend for bench rest accuracy. Try it for yourself and be your own judge. I got the idea from something I read.

[cdoc42]

My experience is the bullet slides into the fired case so easily you can lose it. The case should have expanded enough to release the bullet, then constrict slightly but not enough to easily insert the bullet. That's why external neck turning is done to obtain neck concentricity; it's much easier and more accurate to do than inside neck turning. You can just expand the mouth of the case as is done with handgun rounds to get a start but the question still would remain, why is the case mouth and neck so restrictive after firing?

[603Country]

I was doing all sorts of case prep, neck turning included. I quit doing that and started buying Norma and Lapua cases and doing nothing to them but loading and shooting.

[schmellba99]

I turn necks.

Only needs to be done once, and i am always shocked at how uneven the thickness is on brass (Lapua and Norma included, though not nearly as bad as others).

Does it make a difference? Hell if I know. But I don't mind doing it, therefore it makes a difference to me.

[F. Guffey]

Years ago I asked questions like "Is it stretch? Is it flow? is It stretch and flow? Or is it stretch and or flow? Then there was the donut, forget that one. Then there was reaming, when reaming I must have case neck support, when turning I need support from the inside.

And I form cases, when forming it is not always required. There is always the need to know when to and or when not to ream and or turn.

F. Guffey

[Unclenick]

In general, the reason you can't slip a bullet into your fired case is because is because the case mouth is curled slightly inward. This is normal, though the degree of it varies with how much chamber neck diameter the neck is expanding into and how springy and work-hardened your case neck is, which affects how much it springs back. The more times you size the neck, the harder and more springy it gets.

What happens is building pressure expands the case neck from the case shoulder, rolling forward until gas starts to bleed out between the neck and bullet. At that point there is a pressure gradient along the small gap between the bullet and case mouth, dropping pressure as you approach the mouth down to the level of pressure in the throat area. The bleeding gas is the bypassing propellant gas that goes around the bullet until the bullet moves far enough forward to obturate¹ the bore, and is the gas you see preceding a bullet out of the muzzle of a gun in super slow motion photography. But the gradient means there is then little pressure differential between the inside and outside of the neck near the mouth, so it expands less hard than the early portion does, leaving it curled inward.

Below you can see two cases exhibiting the curl. The lower one is fairly new. The upper one has been fired so many times you not only can see that a "donut" has formed at the inside corner of the neck and shoulder junction, but you can see reamer marks inside the neck where another such donut was removed earlier. Both cases have inward mouth curl, but if you measure them, the more used and springier case would be perhaps half a thousandth to two thousandths smaller all around and that much tighter at the curled-in mouth.



Close up of the curl:



There are three ways to rid yourself of the curl problem. One already described was to outside turn the neck. This thins the brass, allowing it to expand the inside of the neck wider in the chamber neck. That also means resizing will be working the brass over a wider change in diameter from then on, but that's the tradeoff. Necks should start to split a little earlier if you don't also anneal.

That brings us to the second method which is just to anneal the necks so they go back to the lower elasticity they had when new.

The third is to use a mandrel die body and mandrel in your press to widen the necks from the inside before resizing with a bushing die or a custom honed solid die that is wide enough to avoid the use of an expander. The mandrels push down into the case with a long taper, so they don't tend to move necks off-axis as expanders do. This gets the mouth wide enough that the sizing die brings it down to size along with the wider part of the neck.



¹ Despite the way people use "obturate" to refer to upsetting bullets to bore diameter, the dictionary says the word actually means "to seal off". Thus the bullet obturates the bore when it is upset to bore diameter, but the bullet is not itself obturated. It is upset.

[Tinbucket]

I've got some case turning eqquipment but haven't used it since the seventies. Following chamber and case neck specs I turned some of my .270 Wby. Didn't need to as I saw no improvement in anything. It shortened the life of the cartridge cases. The necks see a lot of heat and get brittle and thinner they break before you notice and anneal them.
If you are necking down cases for a smaller diameter or caliber the metal, in the neck will thicken and might/probably will need thinning.