Neck Turning

[NiteQwill]

Impressive, please post pics. Would love to see what sub .1 MOA groups look like, as I know I'll never shoot that accurately. That's pretty much world record benchrest-sized groups

Check my Creedmoor thread, I post my rifle, load, and range report. 0.09 MOA 5 round grouping.

[bsumoba]

Impressive, please post pics. Would love to see what sub .1 MOA groups look like, as I know I'll never shoot that accurately. That's pretty much world record benchrest-sized groups

Check my Creedmoor thread, I post my rifle, load, and range report. 0.09 MOA 5 round grouping.

Get those things to a benchrest match stat! Sub 1/4" aggregate groups will win benchrest matches

[Mike402]

Check my Creedmoor thread, I post my rifle, load, and range report. 0.09 MOA 5 round grouping.

Yea I've had some ~.1 5 shot groups sprinkled in here and there.

I would suggest you run this challenge: http://snipershide.scout.com/forums/...lenge-v1?s=541

It can be pretty humbling but it lets you know where you really stand with your rig. I wish we had something like that on this site, as it makes going to the range a LOT more interesting.

[NiteQwill]

Yea I've had some ~.1 5 shot groups sprinkled in here and there.

I would suggest you run this challenge: http://snipershide.scout.com/forums/...lenge-v1?s=541

It can be pretty humbling but it lets you know where you really stand with your rig. I wish we had something like that on this site, as it makes going to the range a LOT more interesting.

I have actually, but with a 223 setup. I'm a member on the hide. I've posted several groups with my different rigs, including one from my white oak service rifle.

[LynnJr]

When you turn necks it makes the OD of the neck eccentric in relation to the body. The reason for this is the mandrel indicates off the ID. Because the case thickness varies, the ID is always eccentric.

Case weight has to do with neck thickness. The heavier the case, the thicker the neck walls are. That's a fact. For the purposes of neck tension, sorting cases by weight accomplishes the same thing as neck turning.

Whether .002" of runout destroys accuracy is debatable. Most factory chambers are off by that amount so worrying about .002" is silly.

When you turn necks it does not make the neck eccentric.
The reason necks are turned is to not make them eccentric and they are not eccentric in the first place.
All one needs to do to see this is to turn the necks to afitted neck. If they are eccentric from the body they would not chamber.

In general thicker necks would produce heavier weight but this is not a hard fact. You can have a case with very concentric walls that are 0.014 thick for there entire circumference weigh the exact same as a case with a neck 0.016 thick on one section of its circumference. The case that is uniform in thickness would require 0.001 worth of neck clean up to be absolutely perfect and the case that is 0.016 thick one side might need to be turned to 0.012 or thinner to be perfect.

Sorting cases by weight has nothing at all to do with neck tension.
A case that has a perfect neck at 0.014 thickness and a case with 0.016 on one side and 0.012 on the other side may both weigh exactly the same weight but the necks tension will be way different.
This difference will affect seating depth.
The worlds most accurate rifles have one thing in common. The necks have all been turned and they have been turned for a reason other than excersize.

[LynnJr]

CSACannoneer
I am using Barrett brass which is made by IMI.

[Mike402]

I have actually, but with a 223 setup. I'm a member on the hide. I've posted several groups with my different rigs, including one from my white oak service rifle.

You think something like that would work on this site? Has it been tried?

[LynnJr]

Get those things to a benchrest match stat! Sub 1/4" aggregate groups will win benchrest matches

Brian
I see this stuff posted on every forum. Factory guns shooting quarter minute all day long.
We invite the posters to a benchrest match and so far not a single gun has performed as claimed.
It gets even better when they can do it with factory ammo.

[J-cat]

When you turn necks it does not make the neck eccentric.
The reason necks are turned is to not make them eccentric and they are not eccentric in the first place.
All one needs to do to see this is to turn the necks to afitted neck. If they are eccentric from the body they would not chamber.

In general thicker necks would produce heavier weight but this is not a hard fact. You can have a case with very concentric walls that are 0.014 thick for there entire circumference weigh the exact same as a case with a neck 0.016 thick on one section of its circumference. The case that is uniform in thickness would require 0.001 worth of neck clean up to be absolutely perfect and the case that is 0.016 thick one side might need to be turned to 0.012 or thinner to be perfect.

Sorting cases by weight has nothing at all to do with neck tension.
A case that has a perfect neck at 0.014 thickness and a case with 0.016 on one side and 0.012 on the other side may both weigh exactly the same weight but the necks tension will be way different.
This difference will affect seating depth.
The worlds most accurate rifles have one thing in common. The necks have all been turned and they have been turned for a reason other than excersize.

A lot of incorrect.

If the neck is thicker on one side than the other, then the ID is eccentric. Think of a circle within a circle with the inner circle touching the outer. If you indicate off the ID then the whole neck ends up eccentric by the amount of material you remove.

Neck tension is controlled by several variables, with neck thickness being only one. There's that, sized diameter, brass hardness, and most importantly shoulder thickness. Shoulder thickness and diameter applies pressure at the base of the neck (unless you only size half the neck with bushing dies) and is the primary influence on neck tension in conventionally loaded rounds. Since you cannot clean up the shoulder by turning it, you just have to live with the problem or minimize it by sorting the cases by weight.

Yes, uneven neck thickness affects neck tension but you can't magically fix neck tension by turning necks. I have the means to turn necks and inside ream them. I can even inside ream the necks while the whole length of the material is supported in a FL die. I can create a perfect concentric neck. But I don't because it does not beat sorting by weight.

See, sorting by weight gives you most of the benefit with the least amount of effort.

[eric n]

I've never looked for a correlation between weighing brass and neck thickness, so I ask this question.... What if the extra weight is in the web area?

[LynnJr]

A lot of incorrect.

If the neck is thicker on one side than the other, then the ID is eccentric. Think of a circle within a circle with the inner circle touching the outer. If you indicate off the ID then the whole neck ends up eccentric by the amount of material you remove.

Neck tension is controlled by several variables, with neck thickness being only one. There's that, sized diameter, brass hardness, and most importantly shoulder thickness. Shoulder thickness and diameter applies pressure at the base of the neck (unless you only size half the neck with bushing dies) and is the primary influence on neck tension in conventionally loaded rounds. Since you cannot clean up the shoulder by turning it, you just have to live with the problem or minimize it by sorting the cases by weight.

Yes, uneven neck thickness affects neck tension but you can't magically fix neck tension by turning necks. I have the means to turn necks and inside ream them. I can even inside ream the necks while the whole length of the material is supported in a FL die. I can create a perfect concentric neck. But I don't because it does not beat sorting by weight.

See, sorting by weight gives you most of the benefit with the least amount of effort.

JCat
A lot of incorrect indeed.

Most guns that one turns the necks on get fireformed after turning and they get firef in a concentric chamber. The reason for this is to get perfect brass. Likewise Benchrest brass is always sorted by weight or water volume.
In loose chambers eccentric brass might work but with fitted brass in a concentric chamber it won't happen.
If I follow your logic that the necks are eccentric how do they go in the gun a second time? Are you indexing them so the lopsided necks fit in the concentric chamber each time?
As to the shoulder having more influence that is a reloading problem on your part. Nobody who shoots for accuracy seats a bullets base or heel near the neck/shoulder junction with boattail bullets and you can't seat past that junction with a flat based bullet because you won't have any neck tension to hold the bullet. Real flat base bullets have a larger diameter at the base which will iron out the neck tension on seating and allow the bullet to fall into the powder.

I have added a picture of my mandrel with the inside reamer. When you spin a case the first thing you will notice is the only area the cutter touches is the neck/shoulder junction and it only touches it once upon the initial turning.
If it touches it a second time your pushing your shoulders back too much leading to short brass life.

[J-cat]

The problem is you are arguing from the perspective of using a fireformed/necksized case and I'm from the FL side of the field.

You turn your neck, it is eccentric, then you fireform, it is concentric, the. You neck size half of it using a bushing and seat a bullet at a very long OAL thereby avoiding the shoulder altogether. But that's specialty ammo. It only works in one gun. It won't feed from a magazine.

But what if you use a 185LRBT in a 308? You are kinda forced to seat it deep. What if you wanna shoot any bullet in a .300 Win Mag? You have to seat it deep, past the shoulder.

Not everyone handloads specialty rounds. Most handload regular SAAMI spec rounds. That's where I'm coming from. Bottom line, you don't need to use specialty tricks to get accuracy.

[bsumoba]

I've never looked for a correlation between weighing brass and neck thickness, so I ask this question.... What if the extra weight is in the web area?

Ding ding! weight sorting does not necessarily correlate to neck thickness uniformity.

I bet if I take two pieces of brass with the same starting initial weight out of the box that is identical and then turn them to the same neck thickness. I bet if I weigh them that the weights will not be identical afterwards.

Absolutely the weight can be in the web area, in the body, etc.

As a sidenote, my theory (stolen from a well respected shooter in my neck of the woods) is that neck clearance and jumping the bullets helps aid the bullet in entering the lands straighter, thus resulting in better accuracy downrange. If the bullet has ample neck clearance, when that round leaves the brass, the theory is that there is no part of the chamber to impart a force on the round that can cause the bullet to start into the lands crooked. It basically releases from the brass freely. This may mean that non concentric necks, and essentially non-uniform neck tension will still work. Likewise, jumping the bullet may also aid in straightening out the round for that little bit of jump prior to entering the lands. The jump allows the bullet to sort of self center itself as it enters the lands. This is just a theory of course, but to me, makes sense. This is why all my competition guns will have .003-.004" or more neck clearance and I will try to jump almost all of my bullets if I can help it. I do not shoot VLD style bullets typically. If i were to use VLD type bullets, I would still want the neck clearance, but I may pay more attention to the concentricity of my brass and how uniform the bullets are, assuming I am jamming them into to lands.

[J-cat]

Except that it does.

If you sort your brass by weight you'll see an increase in seating pressure and a corresponding increase in velocity resulting from the decrease in case volume.

Get a HydroPress and strap a Magnetospeed to your barrel. Then we'll talk.

[Fjold]

I have a 22.250 built with a .250 neck and it's a pain to turn necks all the time.