Eurooptic vortex burris nightforce sale




teslong borescope digital camera barrel monitor


As an Amazon Associate, this site earns a commission from Amazon sales.









January 5th, 2024

Smart Reloading — Use Expander Mandrels with New Brass

Expander Mandrel reloading case neck tension cartridge brass

Before you load that nice new cartridge brass for the first time, run an expander mandrel down the case necks. This will iron out dents and provide more uniform neck tension. Chose a mandrel diameter that provides appropriate neck tension.

Lapua brass is so good that you’ll be tempted to just load and shoot, if you have a “no-turn” chamber. However, some minimal case prep will ensure more uniform neck tension. Keeping your neck tension very uniform allows more consistent bullet seating. That, in turn, usually yields better accuracy, and lower Extreme Spread and Standard Deviation (ES/SD). Lapua brass, particularly 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win comes from the factory with tighter-than-optimal necks. Before you seat bullets, at a minimum, you should inside chamfer the case mouths, after running an expander mandrel down the necks. The expander mandrels from both Sinclair Int’l and K&M will both leave the necks with enough neck tension (more than .001″) so you can then seat bullets without another operation. We suggest putting a bit of lube on the mandrel before running it down the necks — but remove any lube that gets inside the necks before seating bullets.

Sinclair Expander Tool Mandrel

Both Sinclair and K&M Tools make a die body specifically to hold expander mandrels. The Sinclair version, is shown above. This $32.99 unit fits caliber-specific expander mandrels ($9.99) which measure approximately .001″ less than bullet diameter for each caliber. This is an updated “Gen II” design that completely captures the mandrel within the die so the mandrel cannot pull out. It also has an O-ring in the die cap that allows the mandrel to self-center within the case neck. Sinclair now offers three sizes of die bodies for expander mandrels: .17 -.338 Caliber (#749-011-715WS $32.99); .357 – .50 caliber (#749-008-843WS, $32.99), and a special .50 Cal die body for large-diameter 50 BMG presses (#749-009-163WS, $39.99). All Generation II dies are machined from stainless steel and the standard diameter 7/8-14 dies include the Sinclair Stainless Steel Split Lock Ring.

Once you run the Sinclair expander mandrel down the necks of Lapua brass, after you account for brass spring-back, you’ll have about .002″ neck tension*. This will make the process of seating bullets go much more smoothly, and you will also iron out any dents in the case mouths. Once the case mouths are all expanded, and uniformly round, then do your inside neck chamfering/deburring. The same expander mandrels can be used to “neck-up” smaller diameter brass, or prepare brass for neck-turning.

Forum member Mike Crawford adds: “These expanders can also reduce runout from offset seating. Prior to bullet seating, expand the sized necks to force thickness variance outward. With the Sinclair system, the necks will springback fine, and will not be pulled out of center. This leaves plenty of tension, and bullets seated more centered. I do this, even with turned necks, to get improved seating.”

Mandrels vs. Expander Balls on Decapping Rods
If you haven’t acquired an appropriate expander mandrel for your brass, but you DO have a full-length sizing die with an expander ball, this will also function to “iron out” the necks and reduce tension. However, using a die with an expander ball will work the necks more — since you first size them down, then the ball expands them up again. Typically (but not always), run-out is worse when using an expander ball vs. an expander mandrel.


* This .002″ tension is what we have observed with Lapua 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win brass. This might vary with much smaller or larger cases, and of course a different brand of brass might yield different results. If you get too little tension with your current mandrel, you can get a smaller-diameter mandrel from 21st Century Shooting. 21st Century even offers low-friction Titanium Nitride-coated mandrels.

Permalink Bullets, Brass, Ammo, Reloading No Comments »
November 29th, 2023

Reloading Tip — With New Brass, Use Expander Mandrels

Expander Mandrel reloading case neck tension cartridge brass

Before you load that new cartridge brass for the first time, run an expander mandrel down the case necks. This will iron out dents and provide more uniform neck tension. Chose a mandrel diameter that provides appropriate neck tension.

Lapua brass is so good that you’ll be tempted to just load and shoot, if you have a “no-turn” chamber. However, some minimal case prep will ensure more uniform neck tension. Keeping your neck tension very uniform allows more consistent bullet seating. That, in turn, usually yields better accuracy, and lower Extreme Spread and Standard Deviation (ES/SD). Lapua brass, particularly 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win comes from the factory with tighter-than-optimal necks. Before you seat bullets, at a minimum, you should inside chamfer the case mouths, after running an expander mandrel down the necks. The expander mandrels from both Sinclair Int’l (Brownells) and K&M will both leave the necks with enough neck tension (more than .001″) so you can then seat bullets without another operation. We suggest putting a bit of lube on the mandrel before running it down the necks — but remove any lube that gets inside the necks before seating bullets.

Sinclair Expander Tool Mandrel

Both Sinclair and K&\M Tools make a die body specifically to hold expander mandrels. The Sinclair version, is shown above. This $37.99 unit fits caliber-specific expander mandrels which measure approximately .001″ less than bullet diameter for each caliber. This is an updated “Gen II” design that completely captures the mandrel within the die so the mandrel cannot pull out. It also has an O-ring in the die cap that allows the mandrel to self-center within the case neck. Sinclair now offers three sizes of die bodies for expander mandrels: .17 -.338 Caliber (#749-011-715WS, $53.99); .357 – .50 caliber (#749-008-843WS, $37.99), and a special .50 Cal die body for large-diameter 50 BMG presses (#749-009-163WS, $51.99). All Generation II dies are machined from stainless steel and the standard diameter 7/8-14 dies include the Sinclair Stainless Steel Split Lock Ring.

Once you run the Sinclair expander mandrel down the necks of Lapua brass, after you account for brass spring-back, you’ll have about .002″ neck tension*. This will make the process of seating bullets go much more smoothly, and you will also iron out any dents in the case mouths. Once the case mouths are all expanded, and uniformly round, then do your inside neck chamfering/deburring. The same expander mandrels can be used to “neck-up” smaller diameter brass, or prepare brass for neck-turning.

Forum member Mike Crawford adds: “These expanders can also reduce runout from offset seating. Prior to bullet seating, expand the sized necks to force thickness variance outward. With the Sinclair system, the necks will springback fine, and will not be pulled out of center. This leaves plenty of tension, and bullets seated more centered. I do this, even with turned necks, to get improved seating.”

Mandrels vs. Expander Balls on Decapping Rods
If you haven’t acquired an appropriate expander mandrel for your brass, but you DO have a full-length sizing die with an expander ball, this will also function to “iron out” the necks and reduce tension. However, using a die with an expander ball will work the necks more — since you first size them down, then the ball expands them up again. Typically (but not always), run-out is worse when using an expander ball vs. an expander mandrel.


* This .002″ tension is what we have observed with Lapua 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win brass. This might vary with much smaller or larger cases, and of course a different brand of brass might yield different results. If you get too little tension with your current mandrel, you can get a smaller-diameter mandrel from 21st Century Innovation, with stainless, Black Nitride, or Titanium nitride versions. The Nitride models have less friction.

Permalink Bullets, Brass, Ammo, Gear Review, Reloading No Comments »
November 1st, 2023

Selecting Bushings for Bushing Dies — Tips from John Whidden

John Whidden Dies Neck Bushing diameter reloading

Whidden Gunworks makes great sizing and seating dies. The Whidden full-length sizing die with neck bushing is very popular because it allows you to “tune” the neck tension by using different bushings, with larger or smaller inside diameters. In this video, John Whidden explains how to choose a the right bushing size for use with your neck-sizing and full-length sizing bushing dies.

For most applications, John suggest starting with the caliper-measured outside diameter of a loaded cartridge (with your choice of bullet), and then SUBTRACT about three thousandths. For example, if your loaded round mics at .333, then you would want to start with a 0.330 neck bushing. John notes, however, that you may want to experiment with bushings, going down a thousandth and up a thousandth. With thin In addition, as your brass ages and the necks harden, you may want to change your bushing size.

John Whidden Dies Neck Bushing diameter reloadingQuick Tip: Try Flipping Your Bushings
You may also want to experiment with “flipping” your neck bushings to alternate the side that first contacts the neck of the case. (One side of the bushing is usually marked with the size, while the other side is unmarked.) So try “number side up” as well as “number side down”.

Some folks believe that one side of the bushing may allow a smoother entry, and that this can enhance concentricity. Other people think they can get very slightly more or less neck tension depending on how the bushing is oriented. This is a subtle effect, but it costs nothing to experiment.

If one bushing orientation proves better you can mark the “up” side with nail polish so that you can always orient the bushing optimally. NOTE: We have confirmed that some bushings are actually made with a slight taper. In addition, bushings may get distorted slightly when the brand name and size is stamped. Therefore there IS a reason to try both orientations.

Permalink Bullets, Brass, Ammo, Reloading No Comments »
October 8th, 2023

Optimize Case Neck Tension with Bushings, Expanders, Annealing

Case Loading Neck Tension Sierra Bullets Paul Box

by Sierra Bullets Ballistic Technician Paul Box
One thing that plays a major role in building an accuracy load is neck tension [one of the factors that controls the “grip” on a bullet]. I think a lot of reloaders pretty much take this for granted and don’t give that enough thought.

So, how much neck tension is enough?

Through the years and shooting both a wide variety of calibers and burn rates of powder, I’ve had the best accuracy overall with .002″ of neck tension. Naturally you will run into a rifle now and then that will do its best with something different like .001″ or even .003″, but .002″ has worked very well for me. So how do we control the neck tension? Let’s take a look at that.

First of all, if you’re running a standard sizing die with an expander ball, just pull your decapping rod assembly out of your die and measure the expander ball. What I prefer [for starters] is to have an expander ball that is .003″ smaller than bullet diameter. So for example in a .224 caliber, run an expander ball of .221″. If you want to take the expander ball down in diameter, just chuck up your decapping rod assembly in a drill and turn it down with some emery cloth. When you have the diameter you need, polish it with three ought or four ought steel wool. This will give it a mirror finish and less drag coming through your case neck after sizing.

Tips for Dies With Interchangeable Neck Bushings
If you’re using a bushing die, I measure across the neck of eight or ten loaded rounds, then take an average on these and go .003″ under that measurement. There are other methods to determine bushing size, but this system has worked well for me.

Case Loading Neck Tension Sierra Bullets Paul Box

Proper Annealing Can Deliver More Uniform Neck Tension
Another thing I want to mention is annealing. When brass is the correct softness, it will take a “set” coming out of the sizing die far better than brass that has become too hard. When brass has been work hardened to a point, it will be more springy when it comes out of a sizing die and neck tension will vary. Have you ever noticed how some bullets seated harder than others? That is why.

Case Loading Neck Tension Sierra Bullets Paul Box

Paying closer attention to neck tension will give you both better accuracy and more consistent groups.

Permalink - Articles, Bullets, Brass, Ammo, Reloading No Comments »
July 23rd, 2023

Case Grip on Bullets — Neck Bushing Size is Just ONE Factor

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.

Editor: Guys, this is a VERY important article. You really should read it over carefully, twice. Variations in the force required to release a bullet can significantly affect accuracy and ES/SD. You really need to know how the grip on bullet can be altered by many different factors.

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.

6-time U.S. National Long-Range Champion John Whidden adds: “Our tests show us that the condition of the necks in regards to lubed or not, carbon inside or not, squeaky clean or not, etc., matter even more than the size of the bushing used. An ultrasonically cleaned or brand new dry case neck make for some quite high seating force.”

Redding neck bushingsIn our Shooters’ Forum a reader asked: “How much neck tension should I use?” This prompted a lengthy 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 6mm PPC benchrest 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 - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
November 1st, 2022

Grip on Bullet — Many Factors Involved, Not 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.

Editor: Guys, this is a VERY important article. You really should read it over carefully, twice. Variations in the force required to release a bullet can significantly affect accuracy and ES/SD. You really need to know how the grip on bullet can be altered by many different factors.

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.

5-time U.S. National Long-Range Champion John Whidden adds: “Our tests show us that the condition of the necks in regards to lubed or not, carbon inside or not, squeaky clean or not, etc., matter even more than the size of the bushing used. An ultrasonically cleaned or brand new dry case neck make for some quite high seating force.”

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 - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip 2 Comments »
July 1st, 2022

Choosing the Optimal Neck Bushing Size — Tips from Whidden

John Whidden Dies Neck Bushing diameter reloading

Whidden Gunworks makes great sizing and seating dies. The Whidden full-length sizing die with neck bushing is very popular because it allows you to “tune” the neck tension by using different bushings, with larger or smaller inside diameters. In this video, John Whidden explains how to choose a the right bushing size for use with your neck-sizing and full-length sizing bushing dies.

For most applications, John suggest starting with the caliper-measured outside diameter of a loaded cartridge (with your choice of bullet), and then SUBTRACT about three thousandths. For example, if your loaded round mics at .333, then you would want to start with a 0.330 neck bushing. John notes, however, that you may want to experiment with bushings, going down a thousandth and up a thousandth. With thin In addition, as your brass ages and the necks harden, you may want to change your bushing size.

John Whidden Dies Neck Bushing diameter reloadingQuick Tip: Try Flipping Your Bushings
You may also want to experiment with “flipping” your neck bushings to alternate the side that first contacts the neck of the case. (One side of the bushing is usually marked with the size, while the other side is unmarked.) So try “number side up” as well as “number side down”.

Some folks believe that one side of the bushing may allow a smoother entry, and that this can enhance concentricity. Other people think they can get very slightly more or less neck tension depending on how the bushing is oriented. This is a subtle effect, but it costs nothing to experiment.

If one bushing orientation proves better you can mark the “up” side with nail polish so that you can always orient the bushing optimally. NOTE: We have confirmed that some bushings are actually made with a slight taper. In addition, bushings may get distorted slightly when the brand name and size is stamped. Therefore there IS a reason to try both orientations.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 1 Comment »
May 19th, 2022

Reloading Bench — How to Optimize Case Neck Tension

Case Loading Neck Tension Sierra Bullets Paul Box

by Sierra Bullets Ballistic Technician Paul Box
One thing that plays a major role in building an accuracy load is neck tension [one of the factors that controls the “grip” on a bullet]. I think a lot of reloaders pretty much take this for granted and don’t give that enough thought.

So, how much neck tension is enough?

Through the years and shooting both a wide variety of calibers and burn rates of powder, I’ve had the best accuracy overall with .002″ of neck tension. Naturally you will run into a rifle now and then that will do its best with something different like .001″ or even .003″, but .002″ has worked very well for me. So how do we control the neck tension? Let’s take a look at that.

First of all, if you’re running a standard sizing die with an expander ball, just pull your decapping rod assembly out of your die and measure the expander ball. What I prefer [for starters] is to have an expander ball that is .003″ smaller than bullet diameter. So for example in a .224 caliber, run an expander ball of .221″. If you want to take the expander ball down in diameter, just chuck up your decapping rod assembly in a drill and turn it down with some emery cloth. When you have the diameter you need, polish it with three ought or four ought steel wool. This will give it a mirror finish and less drag coming through your case neck after sizing.

Tips for Dies With Interchangeable Neck Bushings
If you’re using a bushing die, I measure across the neck of eight or ten loaded rounds, then take an average on these and go .003″ under that measurement. There are other methods to determine bushing size, but this system has worked well for me.

Case Loading Neck Tension Sierra Bullets Paul Box

Proper Annealing Can Deliver More Uniform Neck Tension
Another thing I want to mention is annealing. When brass is the correct softness, it will take a “set” coming out of the sizing die far better than brass that has become too hard. When brass has been work hardened to a point, it will be more springy when it comes out of a sizing die and neck tension will vary. Have you ever noticed how some bullets seated harder than others? That is why.

Case Loading Neck Tension Sierra Bullets Paul Box

Paying closer attention to neck tension will give you both better accuracy and more consistent groups.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 4 Comments »
January 9th, 2022

Why You Should Use Expander Mandrels on New Brass

Expander Mandrel reloading case neck tension cartridge brass

Before you load that nice new cartridge brass for the first time, run an expander mandrel down the case necks. This will iron out dents and provide more uniform neck tension. Chose a mandrel diameter that provides appropriate neck tension.

Lapua brass is so good that you’ll be tempted to just load and shoot, if you have a “no-turn” chamber. However, some minimal case prep will ensure more uniform neck tension. Keeping your neck tension very uniform allows more consistent bullet seating. That, in turn, usually yields better accuracy, and lower Extreme Spread and Standard Deviation (ES/SD). Lapua brass, particularly 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win comes from the factory with tighter-than-optimal necks. Before you seat bullets, at a minimum, you should inside chamfer the case mouths, after running an expander mandrel down the necks. The expander mandrels from both Sinclair Int’l and K&M will both leave the necks with enough neck tension (more than .001″) so you can then seat bullets without another operation. We suggest putting a bit of lube on the mandrel before running it down the necks — but remove any lube that gets inside the necks before seating bullets.

Sinclair Expander Tool Mandrel

Both Sinclair and K&M Tools make a die body specifically to hold expander mandrels. The Sinclair version, is shown above. This $32.99 unit fits caliber-specific expander mandrels ($9.99) which measure approximately .001″ less than bullet diameter for each caliber. This is an updated “Gen II” design that completely captures the mandrel within the die so the mandrel cannot pull out. It also has an O-ring in the die cap that allows the mandrel to self-center within the case neck. Sinclair now offers three sizes of die bodies for expander mandrels: .17 -.338 Caliber (#749-011-715WS); .357 – .50 caliber (#749-008-843WS), and a special .50 Cal die body for large-diameter 50 BMG presses (#749-009-163WS, $39.99). All Generation II dies are machined from stainless steel and the standard diameter 7/8-14 dies include the Sinclair Stainless Steel Split Lock Ring.

Once you run the Sinclair expander mandrel down the necks of Lapua brass, after you account for brass spring-back, you’ll have about .002″ neck tension*. This will make the process of seating bullets go much more smoothly, and you will also iron out any dents in the case mouths. Once the case mouths are all expanded, and uniformly round, then do your inside neck chamfering/deburring. The same expander mandrels can be used to “neck-up” smaller diameter brass, or prepare brass for neck-turning.

Forum member Mike Crawford adds: “These expanders can also reduce runout from offset seating. Prior to bullet seating, expand the sized necks to force thickness variance outward. With the Sinclair system, the necks will springback fine, and will not be pulled out of center. This leaves plenty of tension, and bullets seated more centered. I do this, even with turned necks, to get improved seating.”

Mandrels vs. Expander Balls on Decapping Rods
If you haven’t acquired an appropriate expander mandrel for your brass, but you DO have a full-length sizing die with an expander ball, this will also function to “iron out” the necks and reduce tension. However, using a die with an expander ball will work the necks more — since you first size them down, then the ball expands them up again. Typically (but not always), run-out is worse when using an expander ball vs. an expander mandrel.


* This .002″ tension is what we have observed with Lapua 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win brass. This might vary with much smaller or larger cases, and of course a different brand of brass might yield different results. If you get too little tension with your current mandrel, you can get a smaller-diameter mandrel from 21st Century Shooting. 21st Century even offers low-friction Titanium Nitride-coated mandrels.

Permalink News No Comments »
November 20th, 2020

Smarter Reloader — Use Expander Mandrels with Your New Brass

Expander Mandrel reloading case neck tension cartridge brass

Before you load that nice new cartridge brass for the first time, run an expander mandrel down the case necks. This will iron out dents and provide more uniform neck tension. Chose a mandrel diameter that provides appropriate neck tension.

Lapua brass is so good that you’ll be tempted to just load and shoot, if you have a “no-turn” chamber. However, some minimal case prep will ensure more uniform neck tension. Keeping your neck tension very uniform allows more consistent bullet seating. That, in turn, usually yields better accuracy, and lower Extreme Spread and Standard Deviation (ES/SD). Lapua brass, particularly 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win comes from the factory with tighter-than-optimal necks. Before you seat bullets, at a minimum, you should inside chamfer the case mouths, after running an expander mandrel down the necks. The expander mandrels from both Sinclair Int’l and K&M will both leave the necks with enough neck tension (more than .001″) so you can then seat bullets without another operation. We suggest putting a bit of lube on the mandrel before running it down the necks — but remove any lube that gets inside the necks before seating bullets.

Sinclair Expander Tool Mandrel

Both Sinclair and K&M Tools make a die body specifically to hold expander mandrels. The Sinclair version, is shown above. This $32.99 unit fits caliber-specific expander mandrels ($9.99) which measure approximately .001″ less than bullet diameter for each caliber. This is an updated “Gen II” design that completely captures the mandrel within the die so the mandrel cannot pull out. It also has an O-ring in the die cap that allows the mandrel to self-center within the case neck. Sinclair now offers three sizes of die bodies for expander mandrels: .17 -.338 Caliber (#749-011-715WS $32.99); .357 – .50 caliber (#749-008-843WS, $32.99), and a special .50 Cal die body for large-diameter 50 BMG presses (#749-009-163WS, $39.99). All Generation II dies are machined from stainless steel and the standard diameter 7/8-14 dies include the Sinclair Stainless Steel Split Lock Ring.

Once you run the Sinclair expander mandrel down the necks of Lapua brass, after you account for brass spring-back, you’ll have about .002″ neck tension*. This will make the process of seating bullets go much more smoothly, and you will also iron out any dents in the case mouths. Once the case mouths are all expanded, and uniformly round, then do your inside neck chamfering/deburring. The same expander mandrels can be used to “neck-up” smaller diameter brass, or prepare brass for neck-turning.

Forum member Mike Crawford adds: “These expanders can also reduce runout from offset seating. Prior to bullet seating, expand the sized necks to force thickness variance outward. With the Sinclair system, the necks will springback fine, and will not be pulled out of center. This leaves plenty of tension, and bullets seated more centered. I do this, even with turned necks, to get improved seating.”

Mandrels vs. Expander Balls on Decapping Rods
If you haven’t acquired an appropriate expander mandrel for your brass, but you DO have a full-length sizing die with an expander ball, this will also function to “iron out” the necks and reduce tension. However, using a die with an expander ball will work the necks more — since you first size them down, then the ball expands them up again. Typically (but not always), run-out is worse when using an expander ball vs. an expander mandrel.


* This .002″ tension is what we have observed with Lapua 6mmBR, 6.5×47, 6.5 Creedmoor, and .308 Win brass. This might vary with much smaller or larger cases, and of course a different brand of brass might yield different results. If you get too little tension with your current mandrel, you can get a smaller-diameter mandrel from 21st Century Shooting. 21st Century even offers low-friction Titanium Nitride-coated mandrels.

Permalink Bullets, Brass, Ammo, Reloading No Comments »
June 14th, 2020

Precise Neck Expansion with Gage Pin Die from Porter’s Precision

Porter's Precision Gauge Pin Die

Gage Pin Die System Product Review
by F-Class John
Consistent neck tension is often considered key to precision reloading. Neck tension (or interference as it’s more accurately known) helps ensure that the bullet is held with a known amount of pressure ensuring a consistent release each time. The more common expansion method employs expander mandrels. However, there is another lesser-known but very effective method — using GAGE PINS. This article reviews a unique Porter’s Precision Products Reloading Die designed to work with high-quality Gage Pins.

Gage Pins, long-time tool of machinists, are used to measure the size of a bored hole. They come in a variety of sizes and classes. In the reloading world, most people use ZZ Gage Pins that are sized .0005″ apart and are accurate to .0002″. The nice thing about Gage Pins is that you can order them in either a + or – size which means their accuracy errors on one side or the other so by ordering sets of + and – you can effectively make half-sizes. It’s this flexibility and great range of sizes that make Gage Pins so attractive.

For all the good that Gage Pins can do, until now there has not been a handy way to use them in a reloading press. Some folks tried using a bullet puller to hold the Gage Pin. But on many presses, this can be inconvenient because of long handles or unusual height requirements. As a result, I have mostly resorted to using conventional expander mandrels.

But now I have started using precision Gage Pins, thanks to a special new Gage Pin die system from Porter’s Precision Products in Texas. Not long ago I received a video from a friend showing someone using a custom die specifically made for holding Gage Pins. It turns out that Porter’s Precision Products out of Texas makes a custom Gage Pin Die product that consists of a die body, collet, and die cap. Porter’s Precision also sell a wide range of Gage Pins that have been nicely tapered to prevent damage to brass.

Porter's Precision Gauge Pin Die

Using the Porter’s Precision Gauge Pin Die for Expanding Necks
Using the Porter’s Precision Gage Pin die is pretty straight forward with one caveat. The instructions are very clear that the collet must be inserted at an angle into the threaded cap to help ensure it tightens correctly otherwise damage to the collet may occur. Once you do this a couple times it becomes very simple and shouldn’t be a concern, especially since there’s rarely a ready to actually remove the collet unless you’re changing from one caliber range to another.

With the cap and collet now threaded onto the die body, choose the Gage Pin you want to use, insert it into the collet and tighten the cap down. Once the pin is where you want it, use a set of wrenches to firmly tighten the cap down and you’re ready to go. Thread the die in your press and simply adjust the height to ensure the Gage Pin is being inserted fully into the neck of your brass. You want to make sure the entire neck is being expanded without damaging the rim by pushing it to far up inside the die.

General Thoughts — Gage Pins vs. Expander Mandrels
The actual use of Gage Pins on case neck doesn’t vary from expander mandrels. They both accomplish the same goal and which tool you choose really comes down to personal preference. Where Gage Pins really shine is in their durability and the vast selection of sizes/diameters/tolerances. You can even find long-wearing, reduced friction carbide Gage Pins, but they do cost more.

For me, using the Porter’s Precision Die allowed smooth operation and Porter’s Gage Pins are really well-made. This makes expanding a dream even without any lube in the necks (although I still recommend lube when using a steel Gage Pin, as opposed to carbide). If you’ve been in the market for a way to help expand your necks with enhanced consistency, give Gage Pins a try using the Porter’s Precision Gage Pin Die.

Permalink - Articles, Gear Review, New Product, Tech Tip 1 Comment »
June 22nd, 2019

Reloading Basics: Neck Tension, Expander Balls, and Bushings

Case Loading Neck Tension Sierra Bullets Paul Box

by Sierra Bullets Ballistic Technician Paul Box
One thing that plays a major role in building an accuracy load is neck tension. I think a lot of reloaders pretty much take this for granted and don’t give that enough thought.

So, how much neck tension is enough?

Thru the years and shooting both a wide variety of calibers and burn rates of powder, I’ve had the best accuracy overall with .002″ of neck tension. Naturally you will run into a rifle now and then that will do its best with something different like .001″ or even .003″, but .002″ has worked very well for me. So how do we control the neck tension? Let’s take a look at that.

First of all, if you’re running a standard sizing die with an expander ball, just pull your decapping rod assembly out of your die and measure the expander ball. What I prefer is to have an expander ball that [can give] you .002″ in neck tension [meaning the inside neck diameter is about .002″ smaller than the bullet diameter after passing the expander through]. If you want to take the expander ball down in diameter, just chuck up your decapping rod assembly in a drill and turn it down with some emery cloth. When you have the diameter you need, polish it with three ought or four ought steel wool. This will give it a mirror finish and less drag coming through your case neck after sizing.

Tips for Dies With Interchangeable Neck Bushings
If you’re using a bushing die, I measure across the neck of eight or ten loaded rounds, then take an average on these and go .003″ under that measurement. There are other methods to determine bushing size, but this system has worked well for me.

Case Loading Neck Tension Sierra Bullets Paul Box

Proper Annealing Can Deliver More Uniform Neck Tension
Another thing I want to mention is annealing. When brass is the correct softness, it will take a “set” coming out of the sizing die far better than brass that has become to hard. When brass has been work hardened to a point, it will be more springy when it comes out of a sizing die and neck tension will vary. Have you ever noticed how some bullets seated harder than others? That is why.

Case Loading Neck Tension Sierra Bullets Paul Box

Paying closer attention to neck tension will give you both better accuracy and more consistent groups.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 7 Comments »