Proper degree of neck turning?

[jlow]

I’ve heard different opinions on this and was wondering what people’s experience is?

One opinion is to just trim off the high spots. The advantage of this method is it preserves most of the thickness of the neck. The disadvantage is that you still have uneven neck thickness which can cause inconsistent neck tension.

The other opinion is to trim until the neck is of an even thickness within a group of cases. The big disadvantage of this is all the necks will be significantly thinner and thus supposedly more predisposed to neck splits but my question is how true is this if you anneal after every firing?

 

[nra-for-life]

For what its worth, i have been trimming my 22-250 necks to .013...this gives most cases exactly .013 neck thickness....about 1 in 6 cases is a little bit thinner on one side than .013..... sometimes they go down to about .0125... different calibers, as i'm sure you know, have different case neck thicknesses.... this is what i have determined as optimal for the 22-250 lapua brass for me... it is just enough to trim almost all of the cases completely but the ones that are extremely thin still have spots that don't get touched.

it has increased the consistency in seating force required to seat the bullet (verified by force measurement) and also more consistency in the overall length after seating the bullet as well.

I am fairly new to handloading and I have not been able yet to document in increased level of accuracy from neck turning alone... but i do think it is contributing. when i started turning my necks i also changed a few other variables and the groups were tighter but i cant say how much the neck turning alone contributed.

as i understand it, the general consensus on neck turning is this: if you dont have a tight neck chamber then it is pointless to turn any more than you need to get the necks consistent. it will only allow for excess play in the chamber and also will likely shorten the lifespan of your brass.

 

[DennisH]

One opinion is to just trim off the high spots.

This is all I do, just to even out the necks!

Dennis

 

[Steve Blair]

I look at the neck wall thickness of the brass, determine what will completely clean up the neck, order a reamer with a neck .003" over loaded round diameter for small calibers and .004" for larger (7mm & .30) and turn necks to that thickness. If I have the possibility of using multiple manufacturer's brass, I use the thickness from the thinnest, completely turned neck. Within a given cartridge, like .243 Win., the necks are usually reasonably close.

 

[jlow]

The premise that you only need to neck turn brass if you have a tight chamber has been repeated countless number of times but is incorrect. It is true that if you have a tight chamber, you must neck turn to ensure that the brass will fit. However, neck turning has two other effects, one is as you say it affects neck tension consistency which will affect MV and therefore your ES and SDEV which is very important for long distance shooting. The other reason to neck turn is to enhance concentricity of the rounds.

I am thinking of going the route that sleepygator is going i.e. trim until all the brass has the thickness of the thinnest neck. The reason being that if you only trim off the high spots, you can still have significantly different neck thickness of up to one plus thousands. That does not sound like it is a lot but if you neck is only 12 thousands, it is almost 10% thicker in some areas which is a lot since the surface area that holds the bullet i.e. on the neck is very long….

 

[Zia Hunter]

I neck turn all my new brass during the initial case preparation for my bolt and single shot rifles. I measure a sample of the brass to determine a suitable thickness with the intent to remove a minimum amount necessary to achieve a consistent thickness. I primarily neck size w/o an expander plug. It most definitely improves concentricity as well as improved accuracy in my rifles.

 

[DennisH]

The reason being that if you only trim off the high spots, you can still have significantly different neck thickness of up to one plus thousands.

Above is true, I just preped 2 boxes of 308 Lapua brass. When I turned the necks, I still had dull spots on some, some had bad dull spots! I was only taking off 1/2 to 1 thousandths. I could have gone almost double this to completely straighten out the necks! Maybe I should have! But only a few had significant low spots.

I will say this is the worse lot of Lapua Brass I have prepped for my 308. I usually do 2 boxes per year. I threw away about 10 pieces of brass because I "considered" them too BAD to keep! When the base wont fit in the trimmer correctly, there is a problem. Believe me, about 180 cases fit like a glove, about 10 were questionable, the other 10, NO WAY, went in the garbage! They would not evenly sit flush on my loading table, eye noticeable compared to the other brass. The OAL of the case varied excessively, and I am comparing this to previous brass I have prepped over the years. These are bue box brass!

I also have preped Federal and Winchester brass! Now, I use Lapua exclusively, then Winchester comes next. I gave up on Federal for reloads! Federal is good brass, but I cannot prep the brass using the same procedures as I do on Lapua and Winchester! I will use Federal in a pinch or for hunting!

Just kind of surprised, Dennis

 

[nra-for-life]

I look at the neck wall thickness of the brass, determine what will completely clean up the neck, order a reamer with a neck .003" over loaded round diameter for small calibers and .004" for larger (7mm & .30) and turn necks to that thickness. If I have the possibility of using multiple manufacturer's brass, I use the thickness from the thinnest, completely turned neck. Within a given cartridge, like .243 Win., the necks are usually reasonably close.

can you explain this in more detail what you are doing with the reamer?

 

[Steve Blair]

can you explain this in more detail what you are doing with the reamer?

[br]
I am referring to the chambering reamer used in the subject barrel. My approach is to start with the cartridge and work my way out. The cartridge, specific loading and application determine chamber dimensions, barrel length and profile, action type and configuration, trigger, scope (if any) mounting requirements and stock type and configuration. Some applications, like my tactical rifle, have adequate neck clearance for unturned brass because of magazine feeding.

 

[jlow]

I neck turn all my new brass during the initial case preparation for my bolt and single shot rifles. I measure a sample of the brass to determine a suitable thickness with the intent to remove a minimum amount necessary to achieve a consistent thickness. I primarily neck size w/o an expander plug. It most definitely improves concentricity as well as improved accuracy in my rifles.

This does sound like you remove enough so that all the brass have the same neck thickness all the way around. Any problem with neck splits?

 

[Steve Blair]

No, I anneal frequently and the neck expansion is minimal.

 

[jlow]

That is what I figured and was hoping to hear! Thanks!

 

[amlevin]

The advice I first received was to "just knock off the bumps". Have done that from the beginning. I find that in almost all cases, when I cut deep enough to get a little more than half of the neck showing a cut, the rest has fine scratch marks indicating that the area there is only a fraction thinner than the cut area. that way I remove minimal thickness but still get uniform neck tension. This is for a factory chamber and I might do otherwise if I had a custom chambered barrel.

 

[jlow]

The advice I first received was to "just knock off the bumps". Have done that from the beginning. I find that in almost all cases, when I cut deep enough to get a little more than half of the neck showing a cut, the rest has fine scratch marks indicating that the area there is only a fraction thinner than the cut area. that way I remove minimal thickness but still get uniform neck tension. This is for a factory chamber and I might do otherwise if I had a custom chambered barrel.

This is the same advice I originally received and have been using for a while. However I find that I really don't know the difference in thickness between the turned and unturned areas. When I check the neck after purchasing a high quality Mitutoyo Digimatic tube micrometer, the neck thickness were still as much as 1 thousands off between spots – thus the rationale to cut deeper and make sure all the surface gets turned. My only concern was neck splits.