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!”
Lapua offers a FREE Ballistics App. This was the first mobile ballistics App utilizing the 6DOF calculation model, making it one of most accurate ballistics Apps on the market. With this free App you can calculate trajectories, range, bullet drop, turret adjustments and more. Lapua Ballistics offers up-to-date, Doppler-measured Lapua cartridge and bullet data. It also includes the option to define custom bullets manually.
Lapua’s sophisticated FREE Ballistics App has many great features — much more than you’d expect for a free App. If you do much shooting past 300 yards, or use a wide variety of bullets and/or cartridge types, definitely download the App and give it a try. For more details, read the Lapua Ballistics App User Manual. This handy PDF file explains how to set up the App and utilize all its powerful features.
Utilizes 6DOF, the most accurate calculation method
Always available with latest Lapua cartridge / bullet information
Quick and easy to change inputs like distance, wind speed and angle
Several result outputs available, with numerical, reticle, table and graph views
Create and clone your own firearm / reticle combinations
Choose between metric and imperial values
Set Point Blank-range to different sight-in distances and impact windows
Set Aiming point to moving target
Add custom bullets (calculations based on BC G1 or G7 and Siacci method)
Features include Sight-in-POI, Coriolis, Max Range and Cant Angle calculation
Compare up to 3 Lapua cartridge/bullet performances to each other
Custom trajectory tables
After downloading the FREE Lapua Ballistics App for Android device or Apple iPhone/iPad, you’ll want to access the Lapua Ballistics App Guide which shows how to use all the features and options. In addition, Lapua offers a handy FAQ Page with User Tips and Answers to frequently Asked Questions. After downloading the FREE App, you should definitely go to the FAQ page. It has helpful illustrations showing how to set up the App for your firearms and cartridge types. Also check out the page explaining the Sight-In POI feature which allows profiles of different bullet weights in the same firearm.
Watch Video for Explanation of Lapua Ballistics App Features
Recent Lapua Ballistics App Updates
In 2025 Lapua added major Software Updates to its Ballistics App. Enhanced features include:
Range Presets: Create ranges, with angles, and quickly move between them. Output Units: Set the unit of the calculation output to clicks, MRAD, or MOA Device Compass for Shooting Direction: When getting wind data or getting location in Coriolis tab, shooting direction is taken from device compass. Wind Direction Correction: When changing shooting direction, ether by Coriolis tab or Get wind data button, wind direction is corrected by the new shooting direction.
Leveraging the incredible success of the 6.5 Creedmoor cartridge, ammo-makers and rifle manufacturers have teamed up to produce a bigger Creedmoor cartridge — the 7.6 Creedmoor. The latest addition to the Creedmoor line gets its name from its 7.62mm bullet dimension. Yep, that makes it a .30-cal cartridge, but the creators stuck with the metric title for consistency. Makes sense. We like the way “7.6 Creedmoor” sounds and we bet consumers will too. The 6.5 Creedmoor has been a singular success — it is by far the most popular new cartridge introduced in the last decade. We think the 7.6 Creedmoor could become equally successful in short order.
In creating the new 7.6 Creedmoor, the product engineers were primarily concerned with accuracy, reliability, and compatibility. In a brilliant marketing stroke, the 7.6 Creedmoor’s designers crafted this cartridge to be 100% compatible with existing .308 Winchester and 7.62×51 rifles. So you can shoot the 7.6 Creedmoor safely in your existing .308 Win deer rifle or F-TR rig. As one ammo-maker’s marketing manager told us: “The 7.6 Creedmoor gives you everything you liked about the .308 Win, with a trendy name and the undeniable Creedmoor cachet. The 6.5 Creedmoor has become hugely popular. We expect the new 7.6 Creedmoor to do as well, or better!” We agree. Consider this — the 7.6 Creedmoor offers much better barrel life than the 6.5 Creedmoor, along with better bullet selection, particularly for hunters. With these advantages, how could the 7.6 Creedmoor not become a huge hit? The Creedmoor name alone should ensure success.
We discussed the new 7.6 Creedmoor with Dennis DeRille, one of the “founding fathers” of the 6.5 Creedmoor. Dennis said — “The Creedmoor name is synonymous with innovation and tactical success. This new 7.6 should live up to its name as it delivers .308 Win performance in a package for the 21st Century.”
Reassuring .308 Win Ballistics and Die Compatibility
Another great feature of the new 7.6 Creedmoor is that you can use existing .308 Win dies and reloading components. That excited one PRS shooter: “I had all this old .308 brass and .30-Cal bullets sitting around. When I heard about the 7.6 Creedmoor I said ‘Wow this is great, I can use this stuff in a Creedmoor now’. I know it will be accurate based on the name alone. That’s cool — tacticool!”
Because the new 7.6 Creedmoor shares case capacity and design details with the venerable .308 Win, it also shares the .308 Win’s impressive ballistics performance. “Whatever you can do with a .308 Win, you can do with the 7.6 Creedmoor… and then some!” says Hornady. Here is a chart showing projected velocities for the 7.6 Creedmoor with various barrel lengths and bullet weights.
NRA Approves 7.6 Creedmoor for F-TR Competition
Currently, NRA competition rules restrict F-TR rifles to the .308 Win (7.62×51) and .223 Rem (5.56×45) chamberings. But that’s going to change. Starting in June 2026, the NRA will allow 7.6 Creedmoor rifles in all F-TR matches. In addition, the 7.6 Creedmoor can be used in service rifles such as the popular M1A. It’s great to see this old battle rifle updated with Creedmoor accuracy and performance.
USA and Foreign Ammo Makers will Produce 7.6 Creedmoor Ammo
7.6 Creedmoor factory-loaded ammunition will be available from all major USA ammo-makers including Federal, Hornady, CCI, and Remington. As well, foreign ammo-makers Hirtenberger, Sellier & Bellot, and Prvi Partizan have pledged to produce 7.6 Creedmoor ammunition. That’s good news for shooters who want affordable Creedmoor ammo. One ammo-maker told us: “The whole industry is excited about the 7.6 Creedmoor. To be honest, .308 Win ammo sales have been declining for a number of years. Now we can repackage those same great components and market them to a new set of consumers reared on the 6.5 Creedmoor. This is a great deal for ammo-makers, who know how excitable Creedmoor fan-boys can be!”
Efficient cartridges make excellent use of their available powder and case/bore capacity. They yield good ballistic performance with relatively little recoil and throat erosion.
Cartridge Efficiency: A Primer (pun intended!)by USAMU Staff
The U.S. Army Marksmanship Unit (USAMU) published a series of reloading articles on its Facebook Page. In this article, the USAMU discusses cartridge case efficiency and its benefits. While this is oriented primarily toward NRA High Power Rifle and Long Range (1000-yard) competition, these factors also apply to medium/big game hunters. Assuming one’s rifle and ammunition are accurate, key considerations include ballistic performance (i.e., resistance to wind effects, plus trajectory), recoil, and throat erosion/barrel life.
Efficient cartridges make excellent use of their available powder and case/bore capacity. They yield good ballistic performance with relatively little recoil and throat erosion. A classic example in the author’s experience involved a featherweight 7x57mm hunting/silhouette rifle. When loaded to modern-rifle pressures, just 43-44 grains of powder pushed a 139gr bullet at 2900 fps from its 22″ barrel. Recoil in this light rifle was mild; it was very easy to shoot well, and its performance was superb.
An acquaintance chose a “do everything” 7mm Remington Magnum for use on medium game at short ranges. A larger, heavier rifle, it used ~65 grains of powder to achieve ~3200 fps with similar bullets — from its 26″ barrel. Recoil was higher, and he was sensitive to it, which hampered his shooting ability.
Similarly efficient calibers include the 6mm BR [Norma], and others. Today’s highly-efficient calibers, such as 6mm BR and a host of newer developments might use 28-30 grains of powder to launch a 105-107gr match bullet at speeds approaching the .243 Winchester. The .243 Win needs 40-45 grain charges at the same velocity.
Champion-level Long Range shooters need every ballistic edge feasible. They compete at a level where 1″ more or less drift in a wind change could make the difference between winning and losing. Shooters recognized this early on — the then-new .300 H&H Magnum quickly supplanted the .30-06 at the Wimbledon winner’s circle in the early days.
The .300 Winchester Magnum became popular, but its 190-220gr bullets had their work cut out for them once the 6.5-284 and its streamlined 140-142gr bullets arrived on the scene. The 6.5-284 gives superb accuracy and wind performance with about half the recoil of the big .30 magnums – albeit it is a known barrel-burner.
Currently, the 7mm Remington Short Action Ultra-Magnum (aka 7mm RSAUM), is giving stellar accuracy with cutting-edge, ~180 grain bullets, powder charges in the mid-50 grain range and velocities about 2800+ fps in long barrels. Beyond pure efficiency, the RSAUM’s modern, “short and fat” design helps ensure fine accuracy relative to older, longer cartridge designs of similar performance.
Recent design advances are yielding bullets with here-to-fore unheard-of ballistic efficiency; depending on the cartridge, they can make or break ones decision. Ballistic coefficients (“BC” — a numerical expression of a bullet’s ballistic efficiency) are soaring to new heights, and there are many exciting new avenues to explore.
The ideal choice [involves a] balancing act between bullet BCs, case capacity, velocity, barrel life, and recoil. But, as with new-car decisions, choosing can be half the fun!
Factors to Consider When Evaluating Cartridges
For competitive shooters… pristine accuracy and ballistic performance in the wind are critical. Flat trajectory benefits the hunter who may shoot at long, unknown distances (nowadays, range-finders help). However, this is of much less importance to competitors firing at known distances.
Recoil is an issue, particularly when one fires long strings during competition, and/or multiple strings in a day. Its effects are cumulative; cartridges with medium/heavy recoil can lead to shooter fatigue, disturbance of the shooting position and lower scores.
For hunters, who may only fire a few shots a year, recoil that does not induce flinching during sight-in, practice and hunting is a deciding factor. Depending on their game and ranges, etc., they may accept more recoil than the high-volume High Power or Long Range competitor.
Likewise, throat erosion/barrel life is important to competitive shooters, who fire thousands of rounds in practice and matches, vs. the medium/big game hunter. A cartridge that performs well ballistically with great accuracy, has long barrel life and low recoil is the competitive shooter’s ideal. For the hunter, other factors may weigh more heavily.
Cartridge Efficiency and Energy — Another Perspective
Former Lapua staffer Kevin Thomas explains that efficiency can be evaluated in terms of energy:
“Cartridge efficiency is pretty straight forward — energy in vs. energy out. Most modern single-based propellants run around 178-215 ft/lbs of energy per grain. These figures give the energy potential that you’re loading into the rifle. The resulting kinetic energy transferred to the bullet will give you the efficiency of the round. Most cases operate at around 20-25% efficiency. This is just another way to evaluate the potential of a given cartridge. There’s a big difference between this and simply looking at max velocities produced by various cartridges.”
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.
Get 25% OFF Applied Ballistics Books! Use code: READ2026 at checkout.
Today we showcase six YouTube videos that explain basic reloading processes. This article focuses on the .45 ACP cartridge because this a very good choice for hand-loaders getting started. The .45 ACP is one of the easier cartridges to reload, because it has a large case diameter and large primer pocket, and because it operates at relatively low pressures (compared to rifle rounds).
We recommend that new reloaders consider starting with the .45 ACP cartridge. There are many reasons why the .45 ACP is a good choice for those just getting started in hand-loading:
1. The case is fairly short but has a relatively large diameter (and minimal taper), so it is easy to see inside the case. That helps you quickly check powder levels.
2. Many good powders (for the .45 ACP) will fill the case over 60%, so you will have an obvious overflow if you double-charge by accident.
3. The .45 ACP round runs at relatively low pressures, but delivers excellent accuracy.
4. Good .45 ACP brass lasts a long time, is easy to size, and is good for many reloads.
5. Along with 1911s, there are fine .45 ACP revolvers that shoot the round with moon clips.
6. The vast majority of .45 ACP brass uses large pistol primers (although there ARE some small primer pocket varieties*). We find that large primers are easier to pick up and handle if you are using a single primer tool.
The .45 ACP (Automatic Colt Pistol) cartridge is a rimless straight-walled handgun cartridge originally developed in 1904 by John Moses Browning for use in his prototype Colt semi-automatic pistol. After successful military trials, it was adopted as the standard chambering for Colt’s M1911 pistol.
For reloading, there are many good powder choices. We recommend Vihtavuori N320. This is very accurate and burns cleaner than some otherwise good powders, such as Accurate (AA) No. 5 and Unique.
Basic Reloading for the .45 ACP Cartridge
This is the most-viewed .45 ACP reloading video on YouTube. It is directed primarily for the novice or prospective reloader. It covers the basic processes: case inspection, cleaning, trimming, sizing, priming, powder filling, bullet seating, and crimping. The video creator notes: “Trimming pistol/revolver brass is optional and usually not necessary. it was included because that is what I did when I first began reloading, before I found out that handgun brass does not stretch as much as bottleneck rifle brass.”
How To Reload .45 ACP — Basic Tutorial for Newer Reloaders
This is a detailed 20-minute video that shows the reloading process start to finish. The video shows how to clean the cases, deprime, and check them before loading.
In this video the cases are sized and bullets seated using a single-stage RCBS press. The cases are primed using an RCBS hand-priming tool which keeps multiple primers in a tray (see 8:55 time-mark). For efficiency, we recommend seating with a hand tool (or bench-mounted tool) vs. seating primers using the priming system on the press itself. The hand seating tool also gives you a better “feel” for setting the primers.
How To Reload .45 ACP Start to Finish on a Progressive Press
This is a detailed 19-minute video that shows the reloading process start to finish, along with an bit of history on the .45 ACP cartridge. The video begins with case cleaning using a tumbler. The cartridges are loaded with Hodgdon CFE pistol powder, Federal primers, and 230gr plated bullet. Equipment used in the video are: Hornady LnL progressive press, Hornady Carbide die set and taper crimp die, RCBS 505 balance scale, and harbor freight wet tumbler. While we like the efficiency of a progressive press, we recommend that novice hand-loader begin with a single stage or turret press. We recommend a powder that fills the .45 ACP case pretty full. That reduces the risk of double-charging.
Safety First When Loading All Cartridges
Along with the first two instructional videos above, we include two important videos focused on reloading safety. In the first video, UltimateReloader’s Gavin Gear explains how to check your cartridge during the loading process to eliminate squib loads and other defects. In the second video, Starline Brass tech Hunter Pilant explains how to avoid double charges.
Load .45 ACP Safely — Avoid Squib Loads and Overcharges
You need to check the powder level of EVERY round you load. Do this visually BEFORE seating a bullet. (Or, with a progressive press, use a lock-out die that monitors powder levels). This is very important because a squib load (with little or no powder) can leave a bullet lodged in the barrel. A subsequent full, live round can cause a Kaboom with dire consequences.
Preventing Double Charges — Use a Case-filling Powder with .45 ACP
IMPORTANT TIP: Use a bulky powder that fills your case more than half way with a correct charge. “This will over-fill the case if it is double-charged, making it impossible to load. This is one safeguard that can keep you from making a big [mistake]” (Hunter Pilant, Starline). A bulky powder with high fill level will also be easier to see inside the case.
Good Powder Choices for the .45 ACP Cartridge
We know that many of our readers own .45 ACP handguns and load for this extremely accurate “classic” cartridge. When selecting a powder for the .45 ACP, there are many good options. All the major powder manufacturers make propellants with appropriate density and burn rate characteristics for the .45 ACP. Popular choices include: AA #5 (Accurate Powder); Bullseye (Alliant); Clays, HP-38, and Titegroup (Hodgdon); VV N310 and N320 (Vihtavuori); and WW 231 and WST (Winchester). We’ve tried all those powders in a variety of .45 ACP handguns. When we consider all the factors that make for a good pistol powder, we think Vihtavuori N320 is one of the best available propellants for the .45 ACP.
Vihtavuori N320 is very accurate, it meters well, and it burns clean, with minimal smoke and flash. If you haven’t tried VV N320 yet, you should.
Pros and Cons of Different Powders for the .45 ACP
This Editor has personally tried out eight or more different powders for the .45 ACP. Bullseye works but it is very dirty (both smoke out the barrel and sooty powder fouling on case). Though it otherwise burns clean, Titegroup leaves a singular (and nasty) high-temp flame streak on your brass that is hard to remove. AA #5 is a good choice for progressive press newbies as you use more powder so a double charge will (usually) be obvious. I like AA #5 but N320 was more accurate. Clays burns clean but some powder measures struggle with flake powders like this. WW 231 offered excellent accuracy and metered well, but it kicked out sparks with little pieces of carbon that would hit me in the face.
The Progressive Option — Loading .45 ACP on the Dillon 550B
Once you have mastered the basics of reloading for the .45 ACP, if you require large quantities of ammo, you may want to consider getting a progressive press. Progressive presses can significantly increase your ammo output, but there are also important safety considerations. You need to be careful about powder levels and priming. In this video, Gavin Gear explains how to reload safely with a Dillon 550B progressive press. The equivalent current model is the Dillon 550C.
.45 ACP Ammunition Loading Guide — Nosler Data
If you “roll your own” .45 ACP cartridges, there are many good powder choices. Our favorites are Vihtavuori N320, AA No. 5, and Hodgdon TiteGroup, but there are many other good choices. You’ll find these three recommended powders (plus many others) in the .45 ACP Load Data Charts from Nosler. Shown below are the Nosler Guides for 185gr bullets and 230gr bullets. Click each image below to access printable PDF files.
Click for PDF File
Click for PDF File
* However, be aware that CCI and other companies are now manufacturing .45 ACP brass with SMALL PRIMER POCKETS. Whenever you get new brass, be sure so check ALL the cases for primer size, and segregate large and small in two groups. Attempting to push a large primer into a small primer hole can lead to jams, or worse, dangerous detonation. Be CAREFUL!
Want to see a bullet hit a target in ultra-slow motion? Watch this video to witness some amazing things — such as a bullet jacket peeling back like a banana-skin (at time-mark 7:30). A while back, Germany’s Werner Mehl produced this remarkable 10-minute video for the NSSF SHOT Show. This video has has been watched over 15.6 million times, making it one of the most popular shooting-related videos in history. Employing cameras recording at up to 1,000,000 (one million) frames per second, Mehl’s bullet flight video has been called “astounding” and “mesmerizing”. If you haven’t seen it yet, sit back and enjoy!
Watch This Video! It’s Really Something Special…
This remarkable 1 million Frame Per Second video by Werner has over 15,600,000 YouTube Views with 77,000+ likes. It is one of the best high-speed bullet impact videos ever created.
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).
Neck-Wall Thickness is Important Too
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.
This is a detailed 20-minute video that shows the reloading process start to finish. The video shows how to clean the cases, deprime, and check them before loading.
We know that many of our readers own .45 ACP handguns and load for this extremely accurate “classic” cartridge. When selecting a powder for the .45 ACP, there are many good options. All the major powder manufacturers make propellants with appropriate density and burn rate characteristics for the .45 ACP. Popular choices include: AA #5 (Accurate Powder); Bullseye (Alliant); Clays, HP-38, and Titegroup (Hodgdon); VV N310 and N320 (Vihtavuori); and WW 231 and WST (Winchester). We’ve tried all those powders in a variety of .45 ACP handguns. When we consider all the factors that make for a good pistol powder, we think Vihtavuori N320 is one of the best available propellants for the .45 ACP.
