Here’s a very handy cartridge information sheet you will definitely want to save for future reference. Shown below is Page One of the Primer Size and Bullet Diameter Chart created by Graf & Sons. This chart shows the bullet diameter and primer size for more than 320 popular cartridges. The full three-page chart is available in PDF format for easy printing.
NOTE: If you have the PDF reader installed in your browser, the Graf’s Chart may open in a new tab when you click on the image above. To save the three-page PDF file to your computer or device, click the Floppy Disc icon that appears in the lower right (after the PDF file opens). Here is the direct link:http://www.grafs.com/uploads/technical-resource-pdf-file/12.pdf.
Note: There are a few issues which arise from brass sources. For example, if you are making 22 BR from Lapua brass, you’ll want a small rifle primer. And the 6.5 Creedmoor is not listed (it uses Large Rifle primers for most brass, but Small Rifle primers for Lapua brass). There are a couple other oversights, so we recommend that you double-check your brass before you buy a truckload of primers.
Resource Tip from EdLongrange. We welcome reader submissions.
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The most hotly-anticipated cartridge brass, the new-for-2017 6.5 Creedmoor cases from Lapua, arrived late last week at Graf & Sons. With the strength and uniformity for which Lapua brass is famous, this new brass should definitely “raise the bar” for 6.5 Creedmoor and 6mm Creedmoor shooters. Note — the new Lapua 6.5 Creedmoor brass features a small flash hole and small primer pocket. As of 9:00 am Monday morning this brass is in stock at Grafs.com priced at $119.99 per 100-ct box, with a max order of five (5) boxes.
UPDATE: The 6.5 Creedmoor brass sold out after we posted this story. But there will be more coming. You can ask Graf’s to be notified as soon as the next shipment arrives.
TECH TIP: For those who have been loading Hornady or other-brand 6.5 Creedmoor brass with large primer pockets and large flash holes, you may need to reconfigure your reloading tools. Check your sizing die — you may need to change to a smaller-diameter decapping rod. In addition you’ll need to use a small primer size “pusher” on your priming tool.
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When we first ran this story a while back, it generated great interest among readers. By popular request, we’re reprinting this story, in case you missed it the first time around. — Editor
Precision shooters favor premium brass from Lapua, Norma, or RWS. (Lake City also makes quality brass in military calibers.) Premium brass delivers better accuracy, more consistent velocities, and longer life. Shooters understand the importance of good brass, but many of us have no idea how cartridge cases are actually made. Here’s how it’s done.
The process starts with a brass disk stamped from strips of metal. Then, through a series of stages, the brass is extruded or drawn into a cylindrical shape. In the extrusion process the brass is squeezed through a die under tremendous pressure. This is repeated two or three times typically. In the more traditional “draw” process, the case is progressively stretched longer, in 3 to 5 stages, using a series of high-pressure rams forcing the brass into a form die. While extrusion may be more common today, RWS, which makes some of the most uniform brass in the world, still uses the draw process: “It starts with cup drawing after the bands have been punched out. RWS cases are drawn in three ‘stages’ and after each draw they are annealed, pickled, rinsed and subjected to further quality improvement measures. This achieves specific hardening of the brass cases and increases their resistance to extraordinary stresses.” FYI, Lapua also uses a traditional draw process to manufacture most of its cartridge brass (although Lapua employs some proprietary steps that are different from RWS’s methods).
After the cases are extruded or drawn to max length, the cases are trimmed and the neck/shoulder are formed. Then the extractor groove (on rimless cases) is formed or machined, and the primer pocket is created in the base. One way to form the primer pocket is to use a hardened steel plug called a “bunter”. In the photos below you see the stages for forming a 20mm cannon case (courtesy OldAmmo.com), along with bunters used for Lake City rifle brass. This illustrates the draw process (as opposed to extrusion). The process of draw-forming rifle brass is that same as for this 20mm shell, just on a smaller scale.
River Valley Ordnance explains: “When a case is being made, it is drawn to its final draw length, with the diameter being slightly smaller than needed. At this point in its life, the head of the draw is slightly rounded, and there are no provisions for a primer. So the final drawn cases are trimmed to length, then run into the head bunter. A punch, ground to the intended contours for the inside of the case, pushes the draw into a cylindrical die and holds it in place while another punch rams into the case from the other end, mashing the bottom flat. That secondary ram holds the headstamp bunter punch.
The headstamp bunter punch has a protrusion on the end to make the primer pocket, and has raised lettering around the face to form the headstamp writing. This is, of course, all a mirror image of the finished case head. Small cases, such as 5.56×45, can be headed with a single strike. Larger cases, like 7.62×51 and 50 BMG, need to be struck once to form a dent for the primer pocket, then a second strike to finish the pocket, flatten the head, and imprint the writing. This second strike works the brass to harden it so it will support the pressure of firing.”
Thanks to Guy Hildebrand, of the Cartridge Collectors’ Exchange, OldAmmo.com, for providing this 20mm Draw Set photo. Bunter photo from River Valley Ordnance.
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In this video, gunsmith Alex Wheeler explains how to ensure that your full-length sizing dies fit your brass properly. With many cartridge types, it’s not unusual for factory dies to be slightly large in the bottom section. When the diameter of a FL-sizing die is too large near the base, this can leave the bottom section of fired cases “unsized”, with the result that you can have extraction issues and stiff bolt lift, or what Alex calls “clickers”. At the same time, it’s not unusual for dies to over-size fired cases at the shoulder (i.e. reduce the shoulder diameter by .004″ or more).
We strongly recommend that all hand-loaders watch this video, particularly if you load cases 6+ times with relatively high-pressure loads.
Alex explains that a key dimension is the diameter of a fired case 0.200″ above the case head. If your die does not size your fired cases at this point, you should get a FL die that does. This could be a custom die ground to fit your chamber, or it could be a “small-base” die specifically designed to “hit” the bottom section of the case. Alex also notes that some FL dies have an inside chamfer at the mouth of the die, right at the very bottom. (See video at 3:55). This can leave the section of the case right above the extractor groove unsized, which can also lead to “clickers” and stiff bolt lift.
Paint Your Brass to Find Problem Areas
If you are having stiff bolt lift or extraction issues, Alex explains that you can “paint” your brass with magic marker (or dye-chem), and then place the case in your chamber. On the “hot spots” where the case contacts the chamber wall, the marking will rub off, allowing the brass metal to shine through in the problem area(s). This will illustrate where you need better sizing from your die.
“You can ink up the case with some magic marker or dye-chem. If you are getting clickers, go ahead and mark up the case and chamber it and see where it’s wearing. This will help you diagnose [whether the problem] is coming from the base, is it coming maybe from a score in the chamber… it can even happen at the shoulder although that’s pretty rare. Usually the dies size enough at that point.”
Ever wondered what caused a particular bulge or marking on a case? And more importantly, does the issue make the case unsafe for further use? Sierra Bullets Ballistic Technician Duane Siercks offers some insight into various issues and their causes in this article from the Sierra Blog.
Diagnosing Problems with Cartridge Brass
by Duane Siercks, Sierra Bullets
I was handed a small sample of .223 Rem cases the other day and was asked if I could comment on some marks and appearances that had been noticed as they were sorting through the cases. I will share what was observed and give you what would seem to be a cause for them. These were from an unknown source, so I have no way of knowing what type of firearm they were fired in or if they were factory loaded or reloaded ammunition.
Example ONE: Lake City 5.56, Unknown Year
Case #1 was seen to have a very rounded shoulder and split. Upon first look it was obvious that this round had been a victim of excess pressure. The firearm (perhaps an AR?) was apparently not in full battery, or there was possibly a headspace issue also. While taking a closer look, the primer was very flat and the outside radius of the primer cup had been lost. High pressure! Then I also noticed that there was an ejector mark on the case rim. This is most certainly an incident of excessive pressure. This case is ruined and should be discarded. See photo below.
Example TWO: Lake City Match 1993
Case #2 appears very normal. There was some question about marks seen on the primer. The primer is not overly flattened and is typical for a safe maximum load. There is a small amount of cratering seen here. This can be caused by a couple of situations.
Cratering is often referred to as a sign of excess pressure. With safety in mind, this is probably something that should make one stop and really assess the situation. Being as there are no other signs of pressure seen with this case, I doubt that pressure was unsafe. That leads us to the next possibility. This can also be caused by the firing-pin hole in the bolt-face being a bit larger than the firing-pin, and allowing the primer to flow back into the firing-pin hole causing the crater seen here. This can happen even with less-than-max pressures, in fact it has been noted even at starting loads. Always question whether pressure is involved when you see a crater. In this situation, I lean toward a large firing-pin hole. This case should be safe to reload.
Example THREE: R-P .223 Remington
Case #3 appears normal with one exception. There are two rings seen about one half inch below the base of the shoulder. These rings are around the circumference of the case, one being quite pronounced, and the other being noticeably less.
As we do not know the origin of the firearm in which this case was fired, it does seem apparent that the chamber of the firearm possibly had a slight defect. It could have been that the reamer was damaged during the cutting of this chamber. I would suggest that the chamber did have a couple of grooves that imprinted onto the case upon firing. This firearm, while maybe not dangerous should be looked at by a competent gunsmith. In all likelihood, this case is still safe to use.
Example FOUR: R-P .223 Remington
Case #4 has no signs of excess pressure. There is a bulge in the case just ahead of the case head that some might be alarmed by. This bulge is more than likely caused by this case being fired in a firearm that had a chamber on the maximum side of S.A.A.M.I. specifications. There is actually no real issue with the case. Note that the primer would indicate this load was relatively mild on pressure.
If this case was reloaded and used in the same firearm numerous times there might be a concern about case head separation. If you were going to use this case to load in an AR, be sure to completely full-length re-size to avoid chambering difficulties. This case would be safe to reload.
It is very important to observe and inspect your cases before each reloading. After awhile it becomes second nature to notice the little things. Never get complacent as you become more familiar with the reloading process. If ever in doubt, call Sierra’s Techs at 1-800-223-8799.
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Guys — honestly, if you do anything today on this site, watch this video. You won’t be disappointed. Guaranteed. This is a very informative (and surprisingly entertaining) video. Every serious hand-loader should watch this video to see how cartridge cases are made. Your Editor has watched the video 5 times now and I still find it fascinating. The camera work and editing are excellent — there are many close-ups revealing key processes such as annealing and head-stamping.
VERY Informative Video Show Cartridge Brass and Ammunition Production:
Norma has released a fascinating video showing how bullet, brass, and ammunition are produced at the Norma Precision AB factory which first opened in 1902. You can see how cartridges are made starting with brass disks, then formed into shape through a series of processes, including “hitting [the cup] with a 30-ton hammer”. After annealing (shown at 0:08″), samples from every batch of brass are analyzed (at multiple points along the case length) to check metal grain structure and hardness. Before packing, each case is visually inspected by a human being (3:27″ time-mark).
The video also shows how bullets are made from jackets and lead cores. Finally, you can watch the loading machines that fill cases with powder, seat the bullets, and then transport the loaded rounds to the packing system. In his enthusiasm, the reporter/narrator does sometimes confuse the term “bullets” and “rounds” (5:00″), but you can figure out what he means. We definitely recommend watching this video. It’s fascinating to see 110-year-old sorting devices on the assembly line right next to state-of-the art, digitally-controlled production machinery.
Video tip by EdLongrange. We welcome reader submissions.
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On our main Accurateshooter.com website, you’ll find a comprehensive review of the STM system for cleaning cartridge brass with stainless media. To clean brass with stainless media, start with five pounds of small stainless pins sold by StainlessTumblingMedia.com. Place these along with a gallon of water, a little liquid cleaner, and two pounds of cartridge brass in a rotary tumbler, and run the machine for one to four hours.
Forum Member Tests STM System
Our reviewer, Forum member Jason Koplin, purchased the STM media and a new Thumler’s Tumbler. He then tested the STM cleaning procedure on his own brass, including some extremely dirty and tarnished “range pick-up” brass. Jason was thoroughly impressed with how well the STM process worked — as you can see from the “before and after” photos below. Brass which looked like it was ready for the scrap heap was restored to “like-new” appearance. The process works equally well on both rifle brass and pistol brass. Jason observed that one surprise benefit of the STM cleaning procedure is a big reduction in noise. Jason said the water-filled rotary tumbler was much quieter than his vibratory tumblers.
You’ll want to read Jason’s full review which shows more before and after images. The full article features a “how-to” video created by Forum member Cory Dickerson, the young man who pioneered the stainless tumbling process and founded STM. The video shows how to load brass, media, and cleaner solutions into the tumbler, and how to separate media from brass once the tumbling is done.
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Tumblers and walnut/corncob media are old school. These days many shooters prefer processing brass rapidly with an ultrasonic cleaning machine. When used with the proper solution, a good ultrasonic cleaning machine can quickly remove remove dust, carbon, oil, and powder residue from your cartridge brass. The ultrasonic process will clean the inside of the cases, and even the primer pockets. Tumbling works well too, but for really dirty brass, ultrasonic cleaning may be a wise choice.
Our friend Gavin Gear recently put an RCBS Ultrasonic cleaning machine through its paces using RCBS Ultrasonic Case Cleaning Solution (RCBS #87058). To provide a real challenge, Gavin used some very dull and greasy milsurp brass: “I bought a huge lot of military once-fired 7.52x51mm brass (fired in a machine gun) that I’ve been slowly prepping for my DPMS LR-308B AR-10 style rifle. Some of this brass was fully prepped (sized/de-primed, trimmed, case mouths chamfered, primer pockets reamed) but it was gunked up with lube and looking dingy.”
UltimateReloader.com Case Cleaning Video (7.5 minutes):
Gavin describes the cleaning exercise step-by-step on UltimateReloader.com. Read Gavin’s Cartridge Cleaning Article to learn how he mixed the solution, activated the heater, and cycled the machine for 30 minutes. As you can see in the video above, the results were impressive. If you have never cleaned brass with ultrasound before, you should definitely watch Gavin’s 7.5-minute video — it provides many useful tips and shows the cleaning operation in progress from start to finish.
The RCBS ultrasonic cleaning machine features a large 3-liter capacity, 60 watt transducer, and 100 watt ceramic heater. The RCBS ultrasonic machine can be found under $140.00, and this unit qualifies for RCBS Rebates ($10 off $50 purchase or $75 off combined $300.00 purchase). RCBS also sells 32 oz. bottles of cleaning concentrate that will make up to 10 gallons of Ultrasonic Solution.
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If you’re the kind of guy who likes to get his brass shiny inside and out, then wet-tumbling with stainless media gets the job done. For heavy-duty wet-tumbling jobs, it used to be that you had to buy a Thumler’s Tumbler and then figure out your own solution for media separation. Now there are other options on the market which may be more convenient for many users.
Lyman has just introduced its Cyclone Rotary Tumbler. For under $190.00 on Amazon.com, this ships as a complete system with everything you need — even the stainless media and media separators. The Tumbler unit itself holds up to 1000 pieces of .223 Rem brass and features a rubber lining to protect your cases and reduce noise during operation.
Conveniently, a built-in timer can be set from 0 to 3 hours, shutting off automatically. The drum features a large, screw-on end-cap to allow easy loading and unloading. In addition, the tumbler comes with two special sifter pans that make it easy to separate pins from brass. Simply empty the tumbler into the stacked pans. The first pan catches the brass, while the second, finer screen pan catches the pins. Very clever. The Cyclone Tumbler system ships with five pounds of stainless media pins and a sample packet of Brass Cleaning Solution.
Video shows Lyman Cyclone wet tumbling system in action:
TECH TIP: Wet-tumbling brass with stainless media really works. With enough “run-time” the process will definitely remove stubborn carbon on the inside of cases. However, some folks observe that case-mouths can occasionally get peened during the process. This is not a big deal but it is worth noting. In addition, with large flash-hole cases, it is possible (though rare) for a pin to stick in a flash hole. Therefore you should inspect every case before loading in a progressive press or bulk-priming cases with a bench tool.
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Bryce Towsley has authored an informative article on Reclaiming .223 Rem Brass. Writing for Shooting Illustrated Online, Towsley confesses: “I’m a brass horder…. I end every shooting match on my hands and knees. If the rest of the competitors want to litter the range with their discarded cases, I see it as my civic duty to clean up the mess.” If you burn through a lot of .223 Rem ammo on the varmint fields or in multi-gun matches, we suggest you read Towsley’s article.
Towsley advises that you need to be cautious with range pick-up brass: “Range brass is full of dirt, dust, sand and debris that can be damaging to loading dies, as well as causing other problems.” So, range pick-up brass must be cleaned and then sorted carefully. Towsley explains that you should toss brass that is badly dented, and you have to make sure to remove the primer pocket crimp in military brass. This can be done with a crimp reamer or a swaging tool such as the Dillon Super Swage 600. The latter works well, but Towsley cautions: “For the swager to work properly, you must sort the cases by brand and lot, and then readjust the swager for each new lot.”
Trimming Quantities of Brass
Before loading, “reclaimed” range brass should, of course, be full-length sized and you should trim all the brass to the same length. “Cases that are too long can cause all kinds of problems”, explains Towsley.
We envy the system Towsley uses to trim brass. He has a Dillon Rapid Trim 1200B set up on the top of a single-stage press: “You simply insert a case into the shell holder and raise the ram to trim it instantly. The process is so fast, it almost feels like cheating.” The Rapid Trim is a very neat gadget — it even has an attachment for a vacuum hose to remove the cuttings. The photo at right shows a 1200B installed on a Dillon progressive press.
We definitely recommend you read Bryce Towsley’s Reclaiming Range Brass Article from start to finish. The article offers useful advice that will help you reload any rifle cartridge — not just .223 Rem range brass. Towsley also showcases many good labor-saving devices that can speed up and simplify the process of bulk rifle cartridge reloading.
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One of our Forum members complained that he wasn’t able to set his primers flush to the rim. He tried a variety of primer tools, yet no matter what he used, the primers still didn’t seat deep enough. He measured his primers, and they were the right thickness, but it seemed like his primer pockets just weren’t deep enough. He was mystified as to the cause of the problem.
Well, our friend Boyd Allen diagnosed the problem. It was the decapping rod. If the rod is adjusted too low (screwed in too far), the base of the full-diameter rod shaft (just above the pin) will contact the inside of the case. That shaft is steel whereas your case is brass, a softer, weaker metal. So, when you run the case up into the die, the shaft can actually stretch the base of the primer pocket outward. Most presses have enough leverage to do this. If you bell the base of the primer pocket outwards, you’ve essentially ruined your case, and there is no way a primer can seat correctly.
The fix is simple. Just make sure to adjust the decapping rod so that the base of the rod shaft does NOT bottom out on the inside of the case. The pin only needs to extend through the flash hole far enough to knock the primer out. The photo shows a Lyman Universal decapping die. But the same thing can happen with any die that has a decapping rod, such as bushing neck-sizing dies, and full-length sizing dies.
Whenever you use a die with a decapping pin for the first time, OR when you move the die to a different press, make sure to check the decapping rod length. And it’s a good idea, with full-length sizing dies, to always re-check the height setting when changing presses.
Lee Universal Decapping Die on SALE for $9.89
Speaking of decapping tools, MidwayUSA has the Lee Universal Decapping Die on sale this month (June, 2010), for just $9.89 (item 136543). There are many situations when you may want to remove primers from fired brass as a separate operation (prior to case sizing). For example, if your rifle brass is dirty, you may want to de-cap before sizing. Or, if you load on a progressive press, things will run much more smoothly if you decap you brass first, in a separate operation. The Lee Universal Decapping Die will work with cartridges from 17 Fireball all the way up to 45-70. However, NOTE that the decapping pin supplied with this Lee die is TOO LARGE for LAPUA 6.5×47, 6BR, 220 Russian, and Norma 6 PPC flash holes. Because the pin diameter is too large for these brass types, you must either turn down the pin, or decap with a different tool for cases with .059″ flash-holes. Otherwise, the Lee Decapping Die works well and it’s a bargain.
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Can you form a wildcat cartridge such as the 6 Dasher without expending primer, powders, and bullets? Absolutely. Using the hydro-forming method you can form improved cases in your workshop with no firing whatsoever, so there is no wear on your precious barrel. Watch this video to see how it’s done:
6 Dasher Case Hydro-Forming Demonstration:
Forum member Wes J. (aka P1ZombieKiller) has produced a helpful video showing how to form Dasher cases use the Hornady Hydraulic forming die kit. This includes a two-part die (body and piston), and a special shell holder. To form the case, you insert a primer in your virgin brass, top the case off with with a fluid (water or alcohol), then run the case up into the Hydro-forming die. A few stout whacks with a hammer and your case is 95% formed.
Hydro-Forming Procedure Step-by-Step:
1. Insert spent primer in new 6mmBR brass case.
2. Fill with water or alcohol (Wes prefers alcohol).
3. Wipe excess fluid off case.
4. Place case in special Hornady shell-holder (no primer hole).
5. Run case up into Hydraulic forming die.
6. Smack top piston of forming die 3-4 times with rubber mallet or dead-blow hammer.
7. Inspect case, re-fill and repeat if necessary.
8. Drain alcohol (or water) into container.
9. Remove primer (and save for re-use).
10. Blow-dry formed case. Inspect and measure formed case.
Wes achieves very uniform cartridge OALs with this method. He measured ten (10) hydro-formed 6 Dasher cases and got these results: two @ 1.536″; 2 @ 1.537″; and 6 @ 1.538″.
Three or Four Whacks Produces a 95%-Formed Case
With a Hornady hydro-forming die, hydraulic pressure does the job of blowing out the shoulders of your improved case. The process is relatively simple. Place a spent primer in the bottom of a new piece of brass. Fill the case with water, and then slip it into a special Hornady shell-holder with no hole in the middle. Then you run the case up into the forming die. Now comes the fun part. You gently insert a plunger (hydraulic ram) from the top, and give it three or four stiff whacks with a mallet (or better yet, a dead-blow hammer). Remove the plunger and you have a 95% formed case, ready to load.
Hornady supplies a shell holder made specifically for the hydro die; there’s no hole in the bottom of it. Just insert a spent primer into the primer pocket and you’re ready to go. The spent primer combined with the solid shell holder, keeps the water from seeping out of the primer pocket. The primer pushes out a little bit during this process, but it’s impossible for it to come out because of the way the shell holder is designed. The shell holder has a grove which allows the case to slide out of the shell holder even when the primer protrudes a bit.
Story tip from Body Allen. We welcome reader submissions.
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Butch Lambert of ShadeTree Engineering provided this tip. Butch notes that many 6 PPC benchrest group shooters also enjoy shooting in score matches. But to be really competitive in the BR for score game, that means shooting a 30BR, which has a wider, .308-class rim (0.4728″ diameter). Likewise, if you want to compete in 600-yard registered BR events or in varmint matches, you probably want to run a bigger case, such as the 6BR, 6mm Dasher, or 6-6.5×47. Those cartridges also have the larger 0.4728″ rims.
To convert a PPC-boltface action to shoot the bigger cases you can spend a ton of money and buy a new bolt. That can cost hundreds of dollars. The simpler solution is to turn down the diameter of the larger cases on a lathe. Butch explains: “We’ve seen plenty of interest in rebating case rims. This lets you shoot a 30BR in score matches using your PPC action. All you need is a new barrel. This saves buying another bolt, receiver, or rifle if you have a PPC boltface. Anyone who has access to a lathe can do this job pretty easily. Yesterday I turned 150 case in about an hour.” Below are photos of a rebated 6BR case, along with the lathe form tool Butch uses to rebate the case rims.
Cutting Head for Rebating Rims
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Chances are that many of you have packed away your ammo and shooting supplies for the winter. Maybe you put your brass in a storage bin that might also contain solvents, old rags, or used bore swabs. Well, if you use any ammonia-based solvents, we suggest you separate the brass and ammo and keep it away from potential ammonia vapors. This is because long-term exposure to ammonia fumes can cause cracks to form in your brass. This can lead to case ruptures and possible injury.
This case-cracking phenomenon has been called Season Cracking, a form of stress-corrosion cracking of brass cartridge cases. Season cracking is characterized by deep brittle cracks which penetrate into affected components. If the cracks reach a critical size, the component can suddenly fracture, sometimes with disastrous results. If the concentration of ammonia is very high, then corrosion is much more severe, and damage over all exposed surfaces occurs. The brass cracking is caused by a reaction between ammonia and copper that forms the cuprammonium ion, Cu(NH3)4, a chemical complex which is water-soluble. The problem of cracking can also occur in copper and copper alloys such as bronze.
Season Cracking was originally observed by the British forces in India a century ago. During the monsoon season, military activity was reduced, and ammunition was stored in stables until the dry weather returned. Many brass cartridges were subsequently found to be cracked, especially where the case was crimped to the bullet. In 1921, in the Journal of the Institute of Metals, the phenomenon was explained by Moor, Beckinsale, and Mallinson. Apparently ammonia from horse urine, combined with the residual stress in the cold-drawn metal of the cartridges, was responsible for the cracking.
Don’t store ammunition (or brass) for long periods in a box or container holding ammoniated solvents:
The Australia Department of Defense (AUSDOD) has also explored the problem of brass cracking caused, at least in part, by exposure to ammonia. A study was done to see whether the amount of cracking (from ammonia exposure) varied according to the duration and temperature of the annealing process used on the brass. CLICK HERE to read AUSDOD Research Report.
Story idea from Boyd Allen. We welcome reader submissions.
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Here’s something you don’t see very often — Lapua cartridge brass on sale. As part of its Back-to-Black promotion, Brownells has deeply discounted its inventories of Lapua Brass. For most cartridges/calibers, the price has been reduced at least $10.00 per 100-count box. Here are the sale prices, good through the end of the week:
If you want to load ultra-accurate ammo and shoot very small groups, you should read this article, which we are re-publishing by popular demand. Many novice handloaders 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 the ins and outs of neck tension, take some time and read this article carefully.
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.
Bullet grip is affected by many things, such as:
1. Neck-wall thickness.
2. Amount of 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
— 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 significantly, and it can even change if you ultrasonically clean your cases.
In 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.
Neck-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.
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At the recent IBS 600-Yard Nationals, the 6mm Dasher cartridge was the most popular chambering for both Light Guns and Heavy Guns. The Dasher, a 40° improved version of the 6mmBR Norma case, can definitely shoot — no question about that. But the Dasher has one less-than-ideal feature — its very short neck. This makes it more problematic to shoot a wide variety of bullet types — short bullets as well as long. In addition, the short neck makes it harder to “chase the lands” over time.
For those folks who like the performance of the 6mm Dasher, but prefer a longer neck, there is an excellent alternative — the 6mm BRDX. This wildcat shares the 40° shoulder of the Dasher and has nearly the same capacity. Like the Dasher, the 6 BRDX can drive 100-107gr bullets to the same 3000-3050 FPS accuracy node. But the 6 BRDX has a longer neck than the Dasher. Depending on your “blow length”, the 6 BRDX will typically give you about .030″ to .035″ more usable neck length. That may not sound like much, but it is very useful if you have a longish (.110″+) freebore and you still want to shoot shorter bullets in the lands for some applications.
Your editor has a 6mm BRDX and I really like it. The neck is long enough to let me shoot 90-grainers loaded into the lands as well as 105-grainers. Fire-forming is pretty easy. I just load very long (so there is a firm jam) and shoot with 30.0 grains of Varget and a 100+ grain bullet. With a Brux barrel, my BRDX easily shoots quarter-MOA, with some 100-yard groups in the ones in calm conditions. This is with a Stiller Viper Action, and Shehane ST-1000 stock bedded by Tom Meredith.
6mm BRDX Reamer, Dies, and Hydro-Forming Service
It’s not difficult to set up a rifle to run the 6 BRDX. Dave Kiff’s Pacific Tool & Gauge has the reamer (just tell him the freebore you want). Whidden Gunworks offers excellent BRDX sizing and seating dies. And if you don’t like fire-forming, give Darrell Jones of DJsbrass.com a call. Darrell can hydro-form 6 BRDX brass and even turn the necks to your specs. Darrell’s hydro-forming service saves you time and preserves precious barrel life.
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“Once-fired, lot-number-traceable Lake City 7.62×51. This has been de-primed, pocket-swaged, small base body die’d, full-length sized, trimmed with a Gracey Trimmer, and tumbled. Now it’s shiny again. It’s like gourmet macaroni for shooters!” — Dennis Santiago
Our friend Dennis Santiago shoots a variety of disciplines, including Vintage Military Rifle. He burns through a lot of brass, some of it run through gas guns, so he often saves money by acquiring once-fired Lake City Arsenal brass. But that stuff is often pretty ugly when it arrives. For his “previously-owned” Lake City Brass, Dennis does a complete case prep operation and a thorough cleaning/tumbling operation. Special attention is paid to the primer pockets — they are swaged to remove the military crimp. The cases are trimmed and chamfered in one operation using a Gracey Powered Case Trimmer.
Dennis likes once-fired Lake City brass for some applications. The price is right, and with proper attention to detail during case prep, Lake City brass can shoot exceptionally well indeed. You may want to sort Lake City brass by weight. To remove the military crimp you have a variety of options — you can swage it out with a special tool like Dennis does, or you can ream out the crimp. For Wilson trimmer owners, Wilson makes a special Primer Pocket Reamer to remove military crimps. It works very well, as shown below:
Case Processing with the Gracey Trimmer
Designed by Doyle Gracey 30 years ago, the Gracey machine trims, deburs and chamfers in one operation, indexing off the case shoulder. The manufacturer claims the Gracey will process 20 cases per minute while holding .002″ tolerances on trim length. Two steel cutters are employed — one cutter trims the case to length and puts a chamfer on the inside of the case mouth. The second cutter removes the burr from the outside of the case-mouth. A 1/15 hp motor turns 1550 rpm. Interestingly, a clamped rubber hose serves as the “drive shaft” to turn the cutting head.
“This model may have a piece of wood for a base, no on-off swith and a piece of bent sheet metial to contain brass shavings — but it does trim, debur and chamfer with great speed and accuracy at a nice price. The [Gracey] two-bladed cutter requires a little more patience to adjust than the one-piece cutter on the Giraud, but it gets the job done superbly. [The Gracey] does the job for less money, if you’re willing to tinker with the cutter blade adjustment.” Gracey machines are still available new from MatchPrep.com for $335.00 (or $235.00 without motor).
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German Salazar has written a very thorough guide to measuring nearly all the critical dimensions of cartridge brass. In his Measuring the Case article, on his Rifleman’s Journal website, German reviews the tools and techniques required to measure everything from case overall length to case neck concentricity. Step-by-step, German shows how to measure: Case Length, Case Body length (below neck), Neck Diameter, Headspace, Base Diameter, Neck Thickness, and Case Neck Concentricity.
If you are an “advanced reloader” or want to be, you should read German’s article. Not only does German explain the most common measuring procedures, he highlights some alternative methods you might not have tried yet. The article also links to related discussions of more complex measurement tasts, such as determining case body wall thickness variation.
Even if you’re not a competitive shooter, measuring your brass can provide important safety benefits. As German explains in the conclusion of his article: “There are obviously a lot of measurements that can be taken on the cartridge case and in some cases, more than one way to take them. However, the first two that any new reloader must learn are case length and neck clearance, these two are safety concerns and if overlooked can results in serious damage to the rifle and injury to you.”
We are re-publishing this article at the request of Forum members who told us the information proved very valuable. If you haven’t read this Safety Tip before, take a moment to learn how you can inspect your fired brass to determine if there may be a potential for case separation. A case separation can be dangerous, potentially causing serious injury.
On his Riflemans’ Journal blog, German Salazar wrote an excellent article about cartridge Case-Head Separation. We strongly recommend that you read this article. German examines the causes of this serious problem and he explains the ways you can inspect your brass to minimize the risk of a case-head separation. As cases get fired multiple times and then resized during reloading, the cases can stretch. Typically, there is a point in the lower section of the case where the case-walls thin out. This is your “danger zone” and you need to watch for tell-tale signs of weakening.
The photo at the top of this article shows a case sectioned so that you can see where the case wall becomes thinner near the web. German scribed a little arrow into the soot inside the case pointing to the thinned area. This case hadn’t split yet, but it most likely would do so after one or two more firings.
One great tip offered by German Salazar involves using a bent paper clip to detect potential case wall problems. Slide the paper clip inside your case to check for thin spots. German explains: “This simple little tool (bent paper clip) will let you check the inside of cases before you reload them. The thin spot will be immediately apparent as you run the clip up the inside of the case. If you’re seeing a shiny line on the outside and the clip is really hitting a thin spot inside, it’s time to retire the case. If you do this every time you reload, on at least 15% of your cases, you’ll develop a good feel for what the thin spot feels like and how it gets worse as the case is reloaded more times. And if you’re loading the night before a match and feel pressured for time — don’t skip this step!”
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