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.”

In 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.

Neck-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.

Wouldn’t it be nice to have a print resource at your fingertips that has hundreds of true-size cartridge illustrations, plus technical descriptions of thousands of popular cartridge types? That could be a real time-saver. It’s no wonder this book is an Amazon category best-seller.

If you’re a serious shooter, the latest 7th Edition of the Ammo Encyclopedia belongs in your library. Released in late 2022, this 928-page book is probably the most comprehensive and up-to-date book in print covering current and obsolete cartridge and shotshell types. The Ammo Encyclopedia is a massive resource work with 100+ chapters, covering thousands of handgun, rifle, and shotgun cartridges from the past century and a half. This 928-page edition includes over 150 new cartridge profiles. An expanded Trademark Index lists contact information for all current ammunition manufacturers.

One of the best features is a full-color section with actual size drawings of over 320 current rimfire/centerfire cartridges and shotshells. You won’t find that many “life-size” cartridge drawings in one place even on the internet. Cartridge profiles and ballistic charts have been expanded to include many new factory cartridges. An updated Cartridge Index lists both the standard and alternate names for each cartridge in chronological order. The authors have even included air rifle pellets and historical images and charts. This 928-page softcover book is now just $29.99 on Amazon, 40% off list price.

Comments from guys who bought the book:

“This book contains a vast array of information on many modern and even obsolete ammunition. Definitely recommend for any modern reloader novice or experienced.” – Duggaboy460

“It’s a great reference book for individuals who reload their own ammunition. There is a lot more info in this Edition. Everyone who likes this information should have it in their library.” – Reloader

“Very comprehensive with great photos and detailed information. A Must have for anybody with several guns/ammo.” – M.Ibarra

A new Vortex video series, Cartridge Talks Comparisons, looks at multiple variables along with ballistics gel tests to determine the comparative performance of popular cartridge types. Each Month, Cartridge Talks will examine and test two popular cartridges, comparing their head to head performance. In Episode 1, Vortex Nation™ hosts Mark Boardman and Ryan Muckenhirn pit the 6.5 Creedmoor and .308 Winchester cartridges against each other, examining projectile performance. Mark and Ryan then make conclusions about the applications best suited to each cartridge type.

Cartridge Comparison 14-minute video, Highlighting Ballistic Gel Testing

This first Cartridge Talks Episode pits the 6.5 Creedmoor against the .308 Winchester in a head-to-head, ballistics gel-induced bullet battle. Ballistics (drop/drift), penetration ability, terminal performance and other variables are tested with a variety of tools and tests. Viewers are invited to check out Episode 1, and suggest future cartridge battles in the comments section.

Here is the full 67-minute 6.5 Creedmoor vs. .308 Win Cartridge comparison video:

““With the myriad of cartridges available to the big game hunter, picking which chambering is best for you and your application can be a daunting task”, says Muckenhirn. “In Cartridges Talks, we put our biases on the shelf and put as much scientific process to this as possible. From ‘shootability’ and accessibility, to terminal performance as observed in ballistics gel, Cartridge Talks wades through the numbers and figures with you, loads you up with the pertinent information, and helps you select the ideal cartridge for your next hunt!”

Vortex Nation Has 10 MORE Cartridge Comparison Videos. Here are four we recommend. CLICK HERE to view all four videos.

Tactical competitor Zak Smith stores his elevation and wind drift data on a handy laminated data card. To make one, first generate a come-up table, using one of the free online ballistics programs such as JBM Ballistics. You can also put the info in an Excel spreadsheet or MS Word table and print it out.

Above is a sample of a data card. For each distance, the card includes drop in inches, drop in MOA, drop in Mils. It also shows drift for a 10-mph cross wind, expressed in inches, MOA, and mils. Zak explained that “to save space… I printed data every 50 yards. For an actual data-card, I recommend printing data every 20 or 25 yards.” But Zak also advised that you’ll want to customize the card format to keep things simple: “The sample card has multiple sets of data to be more universal. But if you make your own data card, you can reduce the chance of a mistake by keeping it simple.”

Once you have the card you can fold it in half and then have it laminated at a local office store or Kinko’s. Keep this in your pocket, tape it to your stock, or tie the laminated card to your rifle. If you regularly shoot at both low and high elevations, you may want to create multiple cards (since your ballistics change with altitude). To learn more about ballistic tables and data cards, check out the excellent “Practical Long-Range Rifle Shooting–Part 1″ article on Zak’s website.

Scope-Cover Mounted Ballistics Table
Another option is to place your ballistics card on the back of the front flip-up scope cover. This set-up is used by Forum member Greg C. (aka “Rem40X”). With your ‘come-up’ table on the flip-up cover you can check your windage and elevation drops easily without having to move out of shooting position.

Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit.

And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”

Links for JBM Ballistics Program

Credit our buddy Joe Friedrich for this simple yet effective accessory for your benchrest rifle. Joe shoots a .22 LR benchrest rig with a barrel tuner. When he added weights to his tuner, he found his rifle no longer balanced well. He wanted to add some weight in the rear without drilling holes in the stock. He also wanted the weight to be removable, and easily placed on another rifle in his stable. He wanted a weight that could be moved from gun to gun as needed.

At a local sporting goods shop Joe found a 1.5-lb ankle weight that comes in a padded, tubular elastic cover. It’s like a 1.5-lb sausage in a soft, stretchy nylon cover. (Imagine a really fat, heavy bungee cord). Joe simply attached a plastic zip tie at the end to make a loop that fits perfectly over his buttstock. CLICK HERE for full-screen photo.

To “tune” the rifle’s balance, Joe just slides the ankle weight fore and aft on the stock. We have tried this moveable ankle weight on a variety of different BR stocks (including a McMillan Edge) and it worked perfectly. This is a great invention, and would work with sporter rifles and ARs just as well.

NOTE: Obviously, this ring will increase the measured weight of your rifle. So, if you are competing in a registered match with weight restrictions, you have to ensure that your rifle still makes class weight limits with the ankle weight ring in place.

At the request of our Shooters’s Forum members, we’re repeating an excellent article by Steven Blair on wind reading. Steven, a top F-Class shooter, talks about mirage, topography effects, tail winds, and other subtle factors that can cause frustration for shooters. Steve explains that wind effects can be complex — there’s more going on than just velocity and angle. You need to notice things like berm locations and effects of temp changes over the course of the day.

Wind Reading Tips for Competitive Shooters
by Steven Blair, Past California State Long Range F-Open Champion

Assess the Terrain and How the Wind Will Interact with It
Before you begin a match, take a few minutes to look around the range at the terrain, any obstructions, range topography (berms and backstop), and trees, buildings or structures that could affect wind flow over the range. Imagine what might happen if the wind was from the left or right, headwind or tailwind. Depending upon the direction, significant effects may be seen on range. A head or tail wind may ripple across the berms, causing elevation changes, both high and low. A tall side berm, like the east side berm at Ben Avery, may cause turbulence when the wind comes from that direction. Blocking features might shield most of the wind but a break along the range can funnel strong gusts through the gap with no other indications. Take a few notes about the effects of different wind directions and refer to them if the prevailing direction changes. (Tip courtesy Tony Robertson.)

Use a Spotting Scope, Even When Shooting a Scoped Rifle
A good spotting scope can “see” mirage much more clearly than even an expensive rifle scope. Take your spotting scope to the line and position it as sling shooters do, close enough to use without much movement. Focus the scope approximately 1/3 of the way down range or where the most significant wind effects are likely to occur. Take a quick look while waiting for pit service, glance at the flags and compare to your scope sight picture. I often see ambiguous indications at the target through the rifle scope, but see a clear indication of wind direction and speed through the spotting scope at the shorter distance. When shooting the Arizona Palma Championship at Ben Avery last weekend, I was scoring while the wind was coming from the east. Shooters up and down the line were out to the left, losing points. Mirage at the target looked moderate and the flags weren’t indicating strong wind. As I focused the spotting scope back, the mirage suddenly looked like it was flowing twice as fast around 500 yards than it was closer or farther. It wasn’t until I realized that the access road cut through the berm there that I understood what was happening. (Tip courtesy Gary Eliseo.)

Don’t Over-React to Something That May Be an Anomaly
On ranges with sizable berms, a headwind or tailwind can cause significant elevation problems. It is generally not possible to see or predict when this will occur. When the conditions exist that cause elevation changes and other competitors are experiencing the same problem, the best strategy is to ignore it. Certainly, avoid shooting when the head or tail wind is gusting, the same as you would in a crosswind. But, if you react to random, range-induced elevation changes, the only likely result is to make it worse. Whether the problem is caused by range or ammunition, maintain your waterline hold until you have evidence that something has fundamentally changed.

My .284 Shehane will usually require a click or two down during a string as the barrel warms. That is normal and manageable. But, if your shots are just bouncing up and down in the 10 ring, leave it alone. The same is also true of an occasional gust pushing a shot into the 9 ring. If the conditions have not changed and one shot just went out, it may be the result of a random occurrence that was not predictable. (Tip courtesy “School of Hard Knocks”.)

Adjust Spotting Scope Focus and Magnification as Needed to View Mirage vs. Target Details
In F-Class we only need to see mirage, spotters, and scoring disks. That does not take a lot of magnification. My scope is a Nikon 25-75x82mm ED. It is a superb scope for the money and makes it trivial to see minor variations in mirage. It is good to have the high magnification available, and it can always be reduced if necessary. I use different power settings for different situations.

Setting Magnification Levels
During a match, in very good viewing conditions, I set my spotting scope at 75X, full power. The mirage is more subtle in the morning and greater magnification is needed.

During a match with heavy mirage I set my spotting scope at about 40X. I have no problem seeing mirage, even at this magnification.

When practicing at 300 yards or closer I set my spotting scope at max power (75X) so I can see the little 6mm holes from my 6BR rifle. I usually need to focus back and forth between shots to see both bullet holes and mirage.

Steven Blair, 2012 California State Long Range F-Open Champion, has been shooting since childhood and competing for over 30 years. Before retiring, Steve spent 16 years in Engineering and IT with General Atomics. He has held Engineering and Marketing positions with several firearms companies and worked on projects from pistols to 155mm howitzers.

There are three readily-available 17-caliber rimfire rounds now on the market: 17 HMR, 17 WSM, and 17 Mach 2(aka 17 HM2). Aguila also made a .17 rimfire, the .17 PMC/Aguila, but it never became popular. What should be your choice? The 17 HMR is a very popular round, available from multiple manufacturers — CCI, Hornady, and now Norma. The 17 Mach 2 (HM2) is making a resurgence, as it is less expensive than 17 HMR and it can be shot from rifles converted from .22 LR since it shares the .22 LR cartridge OAL. Finally the 17 WSM is, without question, the performance leader among .17-Cal rimfire rounds.

17 HMR — Still the Market Leader in 17-Cal Rimfires

The 17 HMR (Hornady Magnum Rimfire) is popular and well-established. Ammo with a variety of bullet weights and designs is available. Most 17 HMR ammo is priced from $10-$12 per box, and you can get some better deals during sales.

You can buy quality 17 HMR rifles from many makers at all price levels. The Savage A17 with laminated thumbhole stock is a good choice. There were some early issues with the A17, but Savage improved the magwell and now this rifle is very reliable and accurate, particularly with the CCI-brand A17 ammo.

The laminated thumbhole stock version of the Savage A17 is a great carry-around varminter.

Ruger now makes a .17 HMR version of the Ruger Precision Rifle. If you prefer a modular chassis type rig, this is a great option:

Here is a semi-auto 17 HMR fitted with a suppressor. Even with the cameraman just 20 feet away, you can barely hear the shot, and recoil is non-existent. (NOTE: be sure to turn on the sound icon). Varminter Magazine says: “No ground squirrels were spooked during these shots. Quiet is an understatement!”. This may be the ultimate stealth varminter set-up.

17 Mach 2 (17 HM2) — Best Bang for the Buck?

The 17 Mach 2 (17 HM2) is making a comeback. Now leading manufacturers are offering this efficient little rimfire cartridge in some nice rifles. Both Anschutz and Volquartsen will offer new 17 Mach 2 rifles in 2019. Check out this Volquartsen Summit from SHOT Show. It offers a slick, straight-pull toggle bolt, like you’d find on Olympic biathlon rifles.

Considering that 17 HMR ammo costs $14 to $16 per 50ct box, the 17 Mach 2 is an excellent value by comparison. You can now get 50 rounds of CCI 17 Mach 2 for just $8.99 at Midsouth. Grab it while you can.

The Mach 2 propels the same 17gr V-Max bullet as the 17 HMR, but the Mach 2 runs about 16% slower — 2100 fps vs. 2500 for the 17 HMR. For many shooters, it makes sense to use the 17 Mach 2 rather than a 17 HMR. You save money, barrel life is a little longer, and the 17 Mach 2 is still a much more potent cartridge than the .22 LR. Check out this comparison, and note how the 17 Mach 2 has a much flatter trajectory than the .22 LR:

Hornady’s 17 Mach 2 has a 2100 FPS muzzle velocity vs. 1255 FPS for .22 LR.

17 WSM — More Speed, More Energy, and Flatter Trajectory

The 17 WSM (“Winchester Super Magnum”) is the fastest, flattest-shooting rimfire round you can buy. It totally stomps the .22 LR, and even offers significantly better ballistics than the popular 17 HMR. Check out this comparison of three rimfire magnmum cartridges (17 WMS, 17 HMR, and 22 WMR):

And now lead-free 17 WSM ammo is available. This “unleaded” version is impressively flat-shooting. With a 100-yard zero, it drops only 4.3 inches at 200 yards. Compare that with a .22 LR which can drop 18 inches or more from 100 to 200 yards (based on 1150 fps MV).

CLICK HERE for 17 WSM lead-free ammo test article.

The Applied Ballistics Facebook Page features great, interesting new content posted multiple times each week. This resource features videos, test results, accuracy tips, and samples from Bryan Litz’s excellent books on ballistics and the three volume series on Modern Advancements in Long Range Shooting. Here are some highlights from Applied Ballistics’ Facebook posts from the past two weeks. Plus there’s a discount code, READ2026, that can save you 25% on Applied Ballistics books purchased in the month of March.

.22 LR Super Slow Motion Video — Watch the Bullet!

Watch .22 LR Rimfire Projectile Exiting Rifle Muzzle
This video, filmed with an ultra-high-speed camera, shows the milliseconds in time as a .22-caliber bullet travels the first 11 inches after leaving a .22 LR rifle barrel. Applied Ballistics states: “Notice that the bullet is fully obturated to the internal bore dimension — the step/rebate that exists on the unfired bullet where it meets the case gets expanded (obturated) and doesn’t exist on the fired bullet.”

How Important is Case Fill Ratio — You May Be Surprised

Conventional reloading practice is to select a powder that gives you a good case fill, meaning 90%-100% fill ratio for the cartridge and bullet you’re using. But why?

Some say that a higher fill ratio is good because it prevents the powder from settling differently in the case (which could lead to inconsistent ignition and greater MV SD). This explanation sounds good, and went unchallenged for a long time. However, Applied Ballistics has done some interesting testing that sheds new light on the density issue.

Modern Advancements in Long Range Shooting – Vol. 2 contains the results of Applied Ballistics tests of five different cartridge types — .223 Rem to .338 Lapua — loaded with different powders to produce fill ratios of 80%, 90%, and 100%. The testers wanted to see if 100% fill ratios actually gave better results (lower MV SDs) than the lower fill ratios.

Results of testing 3 different loads in 5 different cartridges — The highest MV SD was in fact measured in an 80% fill ratio load. However, the lowest MV SD was also measured for a different 80% load! Seems like the more we learn, the more questions we have. An informative Applied Ballistics podcast covers the Fill Ratio test. Visit Thescienceofaccuracy.com to access this and interesting podcasts.

EDITOR’s NOTE: There were multiple comments from Facebook readers stating that fill ratios 90% and above worked more consistently for them. And the reloading manuals warn against very low fill ratios.

Get 25% Off Applied Ballistics Books in March 2026

Applied Ballistics, through its Science of Accuracy webstore, is currently offering big savings on its popular books — considered to be the best print resources about rifle accuracy/ballistics ever published. This month you can save 25% on all Applied Ballistics book titles by respected expert (and past national champion) Bryan Litz. Use Code READ2026 to get 25% of one or more of these books.

We like well-executed DIY (Do-It-Yourself) projects. You can save money with DIY projects, and often create something unique and special that can’t be purchased from any vendor. That’s the case with this very cool double shooting bench built by Jacob D., a pilot and 6.5 Creedmoor shooter. The design of the bench is smart — it allows two right-handed shooters, but it can also handle a right-hander and a left-hander. (The lefty sets up in the right half of the bench.)

Jacob, who flies for Arizona’s Mesa Airlines, built his own side-by-side benchrest shooting bench. He then posted photos of this on the 6.5 Creedmoor Group Facebook Page. We like this — very nice work Jacob!

Jacob writes: “Sighting in my new Ruger Precision Rifle with Leupold VX3i LRP 6.5-20x50mm and Burris tactical rings, using my benchrest table I built. Very happy with the combo!”

There is plenty of room for two shooters and two rifles on Jacob’s big and sturdy DIY shooting bench.

Montana-based PROOF Research has released a revealing video showcasing carbon fiber firearms technology and the company’s barrel-making process. Viewers will find the 8-minute film an intriguing introduction to composite barrel-making, which employs aerospace carbon fiber wrapped around a steel barrel core. The video showcases the high-tech machines used at PROOF’s production facilities.

This video shows how PROOF Research employs aerospace-grade, high-temperature composite materials to build match-grade carbon fiber-wrapped barrels.

Dr. David Curliss, General Manager of PROOF Research’s Advanced Composite Division, and former head of the U.S. Air Force High Temperature Composites Laboratory, explains how aerospace expertise helps in the development of PROOF’s firearms-related products: “We are able to provide premier materials for PROOF Research for firearms barrels applications as well as the aerospace market. We’re probably the only firearms technology company that has composite materials in orbit around the earth.”