July 9th, 2019

Tool Time: Case-Neck Sorting Tool Works Fast

Sinclair Case Neck Sorting tool reloading benchrest neck-turning

Case Neck thickness sorting gauge Sinclair accurateshooter.comHe who dies with the most toys wins — right? Well Sinclair has another interesting gadget you can add to your reloading bench. The Sinclair Case Neck Sorting Tool lets you quickly sort brass by neck-wall thickness. For those who shoot “no-turn” brass, this can improve neck-tension consistency. Large variances in neck-wall thickness can cause inconsistent neck “grip” on the bullet. Generally, we’ve found that more consistent neck tension will lower ES and (usually) improve accuracy. We know some guys who shoot no-turn 6mmBR brass in competition with considerable success — but their secret is pre-sorting their brass by neck-wall thickness. Cases that are out-of-spec are set aside for sighters (or are later skim-turned).

Watch Case Neck Sorting Tool Operation in Video

How the Case Neck Sorting Tool Works
Here’s how the Sinclair tool works. Cases are rotated under an indicator tip while they are supported on a case-neck pilot and a support pin through the flash hole. The unit has a nice, wide base and low profile so it is stable in use. The tool works for .22 through .45 caliber cases and can be used on .17- and .20-caliber cases with the optional carbide alignment rod. The MIC-4 pin fits both .060 (PPC size) and .080 (standard size) flash holes. Sinclair’s Case Neck Sorting Tool can be ordered with or without a dial indicator. The basic unit without dial indicator (item 749-006-612WB) is priced at $59.99. You can also buy the tool complete with dial indicator (item 749-007-129WB) for $89.99. IMPORTANT: This sorting tool requires caliber-specific Case Neck Pilots which must be ordered separately.

Editor’s Comment: The purpose of this Sinclair tool is rapid, high-quantity sorting of cartridge brass to ascertain significant case-neck-wall thickness variations. Consider this a rapid culling/sorting tool. If you are turning your necks, you will still need a quality ball micrometer tool to measure neck-wall thickness (to .0005) before and after neck-turning operations.

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November 17th, 2018

Case Grip on Bullet — There’s More to Neck Tension Than Just Bushing Size

case neck bushing reloading die tension bullet release

Many novice hand-loaders believe that neck bushing Inside Diameter (ID) size is the only important factor in neck tension. In fact, many different things will influence the grip on your bullet and its ability to release from the case neck. To learn more about neck tension and “case grip”, take the time to read this article carefully. We bet you’ll gain knowledge that will let you load more accurate ammo, with better ES/SD.

Neck Tension (i.e. Grip on Bullets) Is a Complex Phenomenon
While we certainly have considerable control over neck tension by using tighter or looser bushings (with smaller or bigger Inside Diameters), bushing size is only one factor at work. It’s important to understand the multiple factors that can increase or decrease the resistance to bullet release. Think in terms of overall brass-on-bullet “grip” instead of just bushing size (or the internal neck diameter in non-bushing full-length sizing dies).

Bullet grip is affected by many things, such as:

1. Neck-wall thickness.
2. Amount of bullet bearing surface (shank) in the neck.
3. Surface condition inside of neck (residual carbon can act as a lubricant; ultrasonic cleaning makes necks “grabby”).
4. Length of neck (e.g. 6mmBR neck vs. 6mm Dasher).
5. Whether or not the bullets have an anti-friction coating.
6.The springiness of the brass (which is related to degree of work-hardening; number of firings etc.)
7. The bullet jacket material.
8. The outside diameter of the bullet and whether it has a pressure ridge.
9. Time duration between bullet seating and firing (necks can stiffen with time).
10. How often the brass is annealed.
11. Amount (length) of neck sized (e.g. you can size only half the neck).
12. Interior diameter of bushing, or neck section of non-bushing die.

— and there are others…

One needs to understand that bushing size isn’t the beginning and end of neck tension questions, because, even if bushing size is held constant, the amount of bullet “grip” can change dramatically as the condition of your brass changes. Bullet “grip” can also change if you alter your seating depth, and it can even change if you ultrasonically clean your cases.

Redding neck bushingsIn our Shooters’ Forum a reader recently asked: “How much neck tension should I use?” This prompted a Forum discussion in which other Forum members recommended a specific number based on their experience, such as .001″, .002″, or .003″. These numbers, as commonly used, correspond to the difference between case-neck OD after sizing and the neck OD of a loaded round, with bullet in place. In other words, the numbers refer to the nominal amount of interference fit (after sizing).

While these commonly-used “tension numbers” (of .001″, .002″ etc.) can be useful as starting points, neck tension is actually a fairly complex subject. The actual amount of “grip” on the bullet is a function of many factors, of which neck-OD reduction during sizing is just one. Understanding these many factors will help you maintain consistent neck tension as your brass “evolves” over the course of multiple reloadings.

Seating Depth Changes Can Increase or Decrease Grip on Bullet
You can do this simple experiment. Seat a boat-tail bullet in your sized neck with .150″ of bearing surface (shank) in the neck. Now remove the bullet with an impact hammer. Next, take another identical bullet and seat it with .300″ of bearing surface in another sized case (same bushing size/same nominal tension). You’ll find the deeper-seated bullet is gripped much harder.

PPC lapua brassNeck-Wall Thickness is Important Too
I have also found that thinner necks, particularly the very thin necks used by many PPC shooters, require more sizing to give equivalent “grip”. Again, do your own experiment. Seat a bullet in a case turned to .008″ neckwall thickness and sized down .003″. Now compare that to a case with .014″ neckwall thickness and sized down .0015″. You may find that the bullet in the thin necks actually pulls out easier, though it supposedly has more “neck tension”, if one were to consider bushing size alone.

In practical terms, because thick necks are less elastic than very thin necks, when you turn necks you may need to run tighter bushings to maintain the same amount of actual grip on the bullets (as compared to no-turn brass). Consequently, I suspect the guys using .0015″ “tension” on no-turn brass may be a lot closer to the guys using .003″ “tension” on turned necks than either group may realize.

Toward a Better Definition of Neck Tension
As a convenient short-cut, we tend to describe neck tension by bushing size alone. When a guy says, “I run .002 neck tension”, that normally means he is using a die/bushing that sizes the necks .002″ smaller than a loaded round. Well we know something about his post-sizing neck OD, but do we really have a reliable idea about how much force is required to release his bullets? Maybe not… This use of the term “neck tension” when we are really only describing the amount of neck diameter reduction with a die/bushing is really kind of incomplete.

My point here is that it is overly simplistic to ask, “should I load with .001 tension or .003?” In reality, an .001″ reduction (after springback) on a thick neck might provide MORE “grip” on a deep-seated bullet than an .003″ reduction on a very thin-walled neck holding a bullet with minimal bearing surface in the neck. Bushing ID is something we can easily measure and verify. We use bushing size as a descriptor of neck tension because it is convenient and because the other important factors are hard to quantify. But those factors shouldn’t be ignored if you want to maintain consistent neck tension for optimal accuracy.

Consistency and accuracy — that’s really what this all about isn’t it? We want to find the best neck tension for accuracy, and then maintain that amount of grip-on-bullet over time. To do that you need to look not only at your bushing size, but also at how your brass has changed (work-hardened) with time, and whether other variables (such as the amount of carbon in the neck) have changed. Ultimately, optimal neck tension must be ascertained experimentally. You have to go out and test empirically to see what works, in YOUR rifle, with YOUR bullets and YOUR brass. And you may have to change the nominal tension setting (i.e. bushing size) as your brass work-hardens or IF YOU CHANGE SEATING DEPTHS.

Remember that bushing size alone does not tell us all we need to know about the neck’s true “holding power” on a bullet, or the energy required for bullet release. True bullet grip is a more complicated phenomenon, one that is affected by numerous factors, some of which are very hard to quantify.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 3 Comments »
March 12th, 2013

Lapua .260 Rem Brass Proves Very Uniform

If you have a rifle chambered in .260 Remington, you may be wondering if the Lapua .260 Brass is worth the money compared to domestic-made brass. Well, the answer is “yes” if you demand consistent weight and dimensional uniformity (including neckwall thickness).

Mike Harpster of Dead Center Sports took the time to weigh and measure Lapua .260 Rem brass. His test show this brass to be extremely uniform. Weight variance was less than one (1) grain in a 20-case sample. And case neckwall thickness was very consistent.

Report by Mike Harpster: Lapua .260 Rem Brass Test Results (with Comparisons)
I pulled twenty (20) pieces randomly from one Lapua box to do some measurements. I weighed them on my Mettler-Toledo digital lab scale and here are the individual weights of each case. Remarkably, the Lapua brass had less than one grain total weight variance among all 20 cases!

While checking the Lapua brass I remembered I had just received some Winchester brand .308 brass, so I thought it would be interesting to do a comparison between the two brands. I again pulled 20 cases at random from a bag of 50 and repeated the same measurements. The results are shown in the right half of the table below.

Weight Variance Lapua .260 Rem Brass vs. Winchester .308 Brass

LAPUA .260 Rem Brass Winchester .308 Win Brass
Average: 172.20 grains
ES: 0.94 grains
SD: 0.259
Average: 158.49 grains
ES: 2.64 grains
SD: 0.678

Lapua Brass Further Inspection
With sample Lapua .260 Rem cases, I also measured the neck wall thickness in four places with calipers, not the most accurate method but I feel confident that the thickness did not vary more than .001″ over the 20 cases (.0145-.0155). The inside diameter of the neck measured .260 which would give .004 of neck tension out of the box. I visually checked the flash holes and I did not find any flakes of brass or burrs inside, the holes were round and centered.

Winchester Brass Further Inspection
The flash holes on the majority of the Winchester brass were not round or centered and they had large burrs inside. The neck wall thickness was pretty consistent, varying only .0015″ (.0125″ – .014″). As you can see in the photo (right) many of the Winchester cases were badly dented while the Lapua brass showed very few minor dents. The annealing on the necks of the Lapua brass was clearly evident while the Winchester showed no signs of being annealed. [Editor’s note: Winchester tumble-polishes its brass before shipping — so you would not notice annealing coloration if annealing had been done.]

I have never done these measurements on any other brass so I don’t know how they compare, but I am very impressed with the overall quality of the Lapua .260 brass. If they prove to hold up to the repeated firings I get from my Lapua 6BR brass I believe .260 shooters wil be very happy.

Mike Harpster — Dead Center Sports
105 Sunrise Drive
Spring Mills, PA 16875
phone: 814-571-4655
www.deadcentersports.com

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