The February 2013 edition of Shooting Sports USA magazine has an interesting feature by Glen Zediker. In this Transporting Success, Part I article, Zediker explains the advantages of loading at the range when your are developing new loads or tuning existing loads. Glen, the author of the popular Handloading for Competition book, discusses the gear you’ll need to bring and he explains his load development procedure. In discussing reloading at the range, Glen focuses on throwing powder and seating bullets, because he normally brings enough sized-and-primed brass to the range with him, so he doesn’t need to de-prime, re-size, and then re-prime his cases.
Zediker writes: “Testing at the range provides the opportunity to be thorough and flexible. You also have the opportunity to do more testing under more similar conditions and, therefore, get results that are more telling. Once you are there, you can stay there until you get the results you want. No more waiting until next time.”
Zediker starts with three-shot groups: “I usually load and fire three samples [with] a new combination. I’ll then increase propellant charge… based on the results of those three rounds, and try three more. I know that three rounds is hardly a test, but if it looks bad on that few, it’s not going to get any better.”
Glen reminds readers to record their data: “Probably the most important piece of equipment is your notebook! No kidding. Write it down. Write it all down.”
There’s More to the Story…
Editor’s Note: In Zediker’s discussion of loading at the range, he only talks about throwing powder and seating bullets. In fact, Glen opines that: “there is little or no need for sizing.” Well, maybe. Presumably, for each subsequent load series, Zediker uses fresh brass that he has previously sized and primed. Thus he doesn’t need to de-prime or resize anything.
That’s one way to develop loads, but it may be more efficient to de-prime, re-size, and load the same cases. That way you don’t need to bring 50, 80, or even 100 primed-and-sized cases to the range. If you plan to reload your fired cases, you’ll need a system for de-priming (and re-priming) the brass, and either neck-sizing or full-length sizing (as you prefer). An arbor press can handle neck-sizing. But if you plan to do full-length sizing, you’ll need to bring a press that can handle case-sizing chores. Such a press need not be large or heavy. Many benchresters use the small but sturdy RCBS Partner Press, an “O-Design” that costs about $79.00. You may even get by with the more basic Lee Precision Compact Reloading Press, shown in Zediker’s article. This little Lee press, Lee product #90045, retails for under $30.00.
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Do you own an RCBS electronic powder dispenser? If you do, take the time to watch this ChargeMaster Tuning video from 8541 Tactical. This nine-minute video demonstrates how to re-program your Chargemaster to “tune” the dispensing process. The video shows the exact programming procedures to follow, step-by-step. Some folks want a faster powder flow — others tune their machines for a more reliable drop (with fewer over-runs). One cheap and popular modification is to insert a 1″-long section of a McDonald’s straw in the ChargeMaster’s silver dispensing tube. This works surprisingly well to smooth kernel drop and prevent “clumping” that can cause an over-charge. The McDonald’s straw MOD is demonstrated in this video, starting at the 6:22 mark.
Large-Diameter Dispensing Tube Mod
Many folks have had success with the McDonald’s straw modification demonstrated in the above video. However, some folks would like to get even better flow performance (with virtually no clumping). Forum Member Frank B. has come up with a new option using a brass hose fitting with a large outside diameter. The hose fitting (with tape wrapped around the barbed nose section) is placed inside the RCBS dispensing tube (be sure to have some kind of wrap — you don’t want metal-on-metal). Here’s how the unit looks installed:
Frank tells us: “I have found a cure for the over-throw problem. It is a simple 1/4″ barbed hose nipple. I wrapped a couple layers of tape around the barbed end for a snug fit. With this in place, I have thrown 100+ charges of Varget without a single overthrow. The ID of the barbed end needs to be approximately 3/16″ to feed a steady flow. This works because of the larger ID at the drop.”
Frank adds: “You can see in the photo that the powder is not stacking up. You can watch it drop one grain at a time. Hope this will take the aggravation out of your case charging.” For best performance with this brass fitting MOD, we recommend de-burring and smoothing out the front edge of the brass fitting over which the kernels drop.
Brass fitting mod suggested by Boyd Allen. We welcome reader submissions.
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We have all been there…..you place a piece of tumbled brass in the shell-holder of your press, raise it into the die, and suddenly it is like somebody hit the brakes. The case is stuck in the die. Your first instinct is to reverse it out. You crank on the handle, and BANG! The rim rips off the case head and you are looking at a piece of brass stuck in the die.
A stuck case is one of the boo-boos that all of us reloaders have faced from time to time. If proper lubrication is applied, then it should not be a problem. No matter if you are a seasoned reloader or new to it, this situation can happen. Take your time, use the proper procedures, and you will be back in business in no time! This article explains how to avoid stuck cases (through proper lubrication) and how to use a stuck case removal system.
What Causes Stuck Cases
One of the first common mistakes reloaders face is the stuck case. It can be caused by too much or too little lube. Too much and a vacuum can be formed causing the case to become suctioned into the die. Too little lube and friction is the culprit. So what is the cure? There is no exact cure, but the best lube that we have found so far is just a dab of Imperial Sizing Die Wax on your fingers and applied in a thin coat on the body of the case, not the shoulder or neck. Too much of this wax can cause the vacuum effect, or can eventually load your die up with gobs of residue. If it is applied to the shoulder area, or the leftover wax moves up into the shoulder region of the die, you will see dents or dimples in the shoulder. [AccurateShooter.com Editor's Note: For normal full-length sizing of small cases such as 220 Russian/PPC, 6mmBR, 6.5 Grendel, or 6.5x47 Lapua we recommend Ballistol (aerosol) lube. It is very slippery, goes on very thin, and does not gum up the die.]
A great way to ensure that your dies are clean is to use a simple chamber mop with a dab of your favorite solvent on it and clean out the die. Be sure all of the solvent is out after cleaning by spraying the die out with Quickscrub III or use a clean chamber mop. If you are storing your dies, you can apply a thin coat of a good oil to protect the steel such as TM oil or Starrett M1 Spray.
Using a Stuck Case Removal Kit
If you do stick a case in your die there are a few good stuck case removal kits available. Each one works in a similar fashion. I have found the Hornady kit very effective and easy to use.
Basically what you do is remove the die from the press. Unscrew the decapping assembly and pull it out as far as you can. You then need to drill/tap threads into the stuck case head (this is why it is suggested to unscrew the decapping assembly as far as you can to get it clear of the drill bits). Once this is done screw the die back into the press. You then install the included shellholder attachment on the shellholder ram, and thread it into the case via a small wrench. With some elbow grease you can reverse the stuck case out of the die with the leverage of the press, and not damage the die.
However if the case is stuck….REALLY stuck, you may pull out the threads on the case and you are still left with a stuck case in the die without any way to pull it out. If the case is really difficult to remove even with the use of a stuck case removal kit, do not try to be Hercules with the press ram. Here is a trick that may work. Take the die with the stuck case and place it in your freezer for a couple of hours. Then repeat the removal with the cold die. The freezing temperatures may cause the brass to contract, and make removal easier. If this does not work it is recommended to send it to the die manufacturer. They will be able to remove the case without damaging the die.
Another fix if you can remove the decapping assembly completely is to use a tap hammer and a punch or small wooden dowel to knock the stuck case out. This isn’t the best way since it is very possible that you will damage the die internally or externally on the threads, or both. Send the die to the manufacturer to have this done properly. You will be happier in the long run.
In our Shooters’ Forum, many questions are asked about QuickLOAD software — how to get best results, how to use the advanced features, how to adjust for temperature and so on. To help answer those questions, here’s a short feature we first ran during SHOT Show 2012. You can also CLICK HERE for a very detailed explanation of QuickLOAD in our main site.
At SHOT Show, we had the chance to meet with German software engineer Hartmut Broemel, creator of QuickLOAD software. This software program, while not a substitute for conventional load manuals, allows shooters to evaluate a wide range of powders and bullets, comparing potential loads on the basis of predicted pressures, velocities, load density and projectile in-barrel time.
We took the opportunity, in the video below, to explain some of the fine points of QuickLOAD for our members. QuickLOAD, sold by Neconos.com, helps reloaders understand how changing variables can affect pressures and velocities. It can predict the effect of changes in ambient temperature, bullet seating depth, and barrel length.
In the video below we explain how to adjust the program for true case capacity, bullet seating into the lands, and other important factors. If you are a new QuickLOAD user, or are contemplating buying the $152.95 program, you should watch the video. The program isn’t perfect, but it can accelerate the load development process, and it can save you money by narrowing down the list of appropriate powders for your cartridge.
No other product currently available to serious reloaders offers as much predictive power as QuickLOAD, and you’ll find your money well spent just for the vast collection of data on bullets and cartridges. With a couple mouse-clicks you can instantly get the specifications of hundreds of bullets and cartridges. Likewise, in a matter of seconds, you can compare load density for a half-dozen powders, or compare the projected velocities of one cartridge versus another.
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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, Midsouth Shooters Supply sells the Lee Universal Decapping Die for just $9.34 (item 006-90292), a very good deal. 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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When your cases become hard to extract, or you feel a stiff bolt lift when removing a cartridge, it’s probably time to full-length size your cases, and “bump” the shoulder back. With a hunting load, shoulder bumping may only be required every 4-5 loading cycles. Short-range benchrest shooters, running higher pressures, typically full-length size every load cycle, bumping the shoulder .001-.002″. High Power shooters with gas guns generally full-length size every time, and may need to bump the shoulders .003″ or more to ensure reliable feeding and extraction.
Use Shims for Precise Control of Shoulder Bump
Some shooters like to set the “default” position for their full-length die to have an “ample” .003″ or .004″ shoulder bump. When they need less bump, a simple way to reduce the amount of shoulder movement is to use precision shims in .001″ (one-thousandth) increments.
Mats Johansson writes: “I’ve been using [shims] since Skip Otto (of BR fame) came out with them. I set up my dies with the .006″ shim, giving me the option of bumping the shoulder a bit more when the brass gets old and hardens while still having room to adjust up for zero headspace, should I have missed the original setup by a thou or two. Hunting rounds can easily be bumped an extra .002-.003″ for positive, no-crush feeding. Being a safety-oriented cheapskate, I couldn’t live without them — they let me reload my cases a gazillion times without dangerous web-stretching. Shims are a must-have, as simple as that.”
Sinclair Int’l offers a 7-piece set of Die Shims that let you adjust the height of your die (and thereby the amount of bump and sizing) in precise .001″ increments. Sinclair explains: “Some handloaders will set their die up to achieve maximum sizing and then progressively use Sinclair Die Shims between the lock ring and the press head to move the die away from the shellholder. Doing this allows you to leave the lock ring in the same position. These shims are usually available in increments of .001″ and work very well.”
Seven Shims from .003″ to .010″
Sinclair’s $12.49 Die Shim Kit (item 22400) includes seven shims in thicknesses of .003, .004, .005, .006, .007, .008, and .010. For ease of use, shim thickness is indicated by the number of notches cut in the outer edge of each shim. Even without looking you can “count” the notches by feel.
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Do you use bushings to size your case-necks? Are you assuming that your bushings are actually round on the inside, with a hole that’s centered-up properly? Well you may be in for an unpleasant surprise, based on what our friend Jim de Kort recently discovered. Jim was concerned about the run-out on his brass. His cases went into his bushing-equipped FL die pretty straight, but came out of the die with up to .004″ run-out. “What gives?”, Jim wondered. “Could the problem be the bushings themselves?”
To answer that question, Jim decided to examine his bushings. Using an Accuracy One Wheel-drive concentricity gauge, Jim checked out some of his neck bushings. What he discovered may surprise you…
Neck Bushing Flaws Revealed
Trust no one… — Jim de Kort
Jim writes: “I measured the concentricity of my 6BR rounds today. I noticed they went into the neck-bushing equipped full-length sizing die with <.001" deviation but came out with .003-.004". The culprit, it appears, was the bushing itself. Without it the cases stayed within .0005" to .001" deviation, so something was happening with the bushing.
One bushing had .00025" deviation on the outside, yet almost .003" on the inside, so it is crooked. But even when using a bushing that is within .001" I still get .003" runout after sizing. I repeated the same procedure for my 6x47 and got the same results. When using the bushing, concentricity suffers a lot."
Before we bash the bushing-makers, we must acknowledge that many different things can contribute to excessive run-out and/or mis-alignment of case-necks. We don’t have all the answers here, and Jim would be the first to say that some mysteries remain. Still, these are interesting results that give all precision hand-loaders something to think about.
Jim Borden also offers this tip: “Check the trueness of the face of the die cap. That has more to do with trueness than the bushing. Also check perpendicularity of hole in bushing to top surface. When I was making dies, the cap was made by threading and facing the threaded tenon in same setup.”
Editor’s Comment: Many people have great results with neck-bushing dies, but Jim isn’t the only fellow who has seen some very odd results. I personally employ honed, non-bushing dies for many of my chamberings. These non-bushing dies (with the necks honed for .002-.003″ neck tension) produce extremely straight ammo, with run-out consistently under .0015″.
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Here’s an inexpensive procedure that can help you load straighter ammo, with slightly better measured concentricity (i.e. less run-out) on the case necks and bullets. Simply use a rubber O-Ring on the underside of the die locking ring. This allows the die to self-align itself (slightly) to the case that is being sized. Without the O-Ring, if the flat surface on the top of your press is not perfectly square with the thread axis, your die can end up slightly off-angle. This happens when the bottom of the locking ring butts up tight against the top of the press. The O-Ring allows the die to float slightly, and that may, in turn, reduce the amount of run-out induced during case sizing.
Top prone shooter German Salazar has tried this trick and he says it works: “Go to your local hardware store and get a #17 O-Ring (that’s the designation at Ace Hardware, don’t know if its universal). Slip the O-Ring on the die and re-adjust the lock ring so that the O-Ring is slightly compressed when the die is at the correct height. Size and measure a few more cases. You will probably see a slight improvement in neck concentricity as the die can now float a bit as the case enters and leaves it. This isn’t going to be a dramatic improvement, but it’s a positive one.” We want to stress that adding O-Rings to sizing dies may help some reloaders, but we don’t offer this as a panacea. Try it — if using the O-Ring reduces measured runout that’s great. If it doesn’t, you’ve only spent a few pennies to experiment.
Lee Precision makes die lock rings with built-in O-Rings. Lee’s distinctive lock ring design allows the same kind of self-alignment, which is good. However, Lee lock rings don’t clamp in place on the die threads, so they can move when you insert or remove the dies — and that can throw off your die setting slightly. By using an O-Ring under a conventional die lock ring (that can be locked in place), you get the advantages of the Lee design, without the risk of the lock ring moving.
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A while back, Sinclair International’s Reloading Press Blog featured a “round-table” discussion of reloading techniques. Sinclair’s team of tech staffers were asked: “What do you feel is the one-most crucial step in precision reloading?”
Here are their responses (along with comments from our Editors):
Phil Hoham: “I feel that when working up a load do not go too high or too low in your powder charge. Stay away from “suggested loads” you hear at the range, or on the internet. Always be sure to use a published reloading manual that presents not only minimums and maximums, but also pressure, velocity, and a proper range of powders used. Do not get distracted in the reloading process, and remain focused at all times during each step involved.”
AccurateShooter.com: Some loads presented on the Internet are OK as a starting point, but it is absolutely critical to understand that pressure maximums will vary considerably from one rifle to another (of the same chambering). For example, one 6mmBR rifle shooting 105gr bullets can max out with 30.0 grains of Varget powder, while another rifle, with the same chamber dimensions, but a different barrel, could tolerate (and perform better) with half a grain more powder. You need to adjust recommended loads to your particular rifle and barrel.
Pete Petros: “This could be a very broad topic, but if I were to pick one, it would be making sure to pay close attention, and weigh each and every powder charge to ensure that each load is exact and consistent. This is important not only for accuracy, but also for safety reasons.”
AccurateShooter.com: If you’re shooting beyond 200 yards, it is critical to weigh your loads with an accurate scale. Loads that are uniform (within a few kernels) will exhibit lower Extreme Spread and Standard Deviation. And remember, even if you stick with the same powder, when you get a new powder lot, you may have to adjust your load quite a bit. For example, .308 Palma shooters have learned they may need to adjust Varget loads by up to a full grain from one lot of Varget to the next.
Ron Dague: “I feel that the most important step(s) in reloading for accuracy are in the initial case prep. Uniforming the primer pocket to the same depth to ensure consistency in primer seating is a crucial step. Additionally de-burring the flash holes, each in the same way to clean up and chamfer the inside is important. It ensures that the ignition from the primer is uniform and flows out in the same consistent pattern. Doing so will create uniform powder ignition and tighten up your velocity Extreme Spread.”
AccurateShooter.com: With some brands of brass, primer pocket uniforming and flash-hole deburring is useful. However, with the best Lapua, Norma, and RWS brass it may be unnecessary, or worse, counter-productive. So long as your Lapua brass flash-holes are not obstructed or smaller than spec, it may be best to leave them alone. This is particularly true with the small flash holes in 220 Russian, 6BR, and 6.5×47 cases. MOST of the flash-hole reaming tools on the market have cutting bits that vary in size because of manufacturing tolerances. We’ve found tools with an advertised diameter of .0625″ (1/16″) that actually cut an 0.068″ hole. In addition, we are wary of flash-hole deburring tools that cut an aggressive inside chamfer on the flash-holes. The reason is that it is very difficult to control the amount of chamfer precisely, even with tools that have a depth stop.
Rod Green: “I feel that bullet seating is the most important step. If you had focused on making sure all prior steps (case prep, powder charge, etc.) of the process have been carefully taken to ensure uniformity, bullet seating is the last step, and can mean all the difference in the world in terms of consistency. Making sure that the bullet is seated to the same depth each time, and time is taken to ensure that true aligned seating can make the load.”
Bob Blaine: “I agree with Rod. I strongly feel that consistent bullet seating depth is the most important step in creating the most accurate hand loads. I have seen the results in both my bench and long range rifles. Taking the time to ensure exactness in the seating process is by far, the number one most important step in my book.”
AccurateShooter.com: Agreed. When loading match ammo, after bullet seating, we check every loaded round for base of case to ogive length. If it varies by more than 3 thousandths, that round is segregated or we attempt to re-seat the bullet. We measure base of case to bullet ogive with a comparator mounted on one jaw of our calipers. You may have to pre-sort your bullets to hold the case-base to ogive measurement (of loaded rounds) within .003″.
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Every summer weekend, there are probably 400 or more club “fun matches” conducted around the country. One of the good things about these club shoots is that you don’t have to spend a fortune on equipment to have fun. But we’ve seen that many club shooters handicap themselves with a few common equipment oversights or lack of attention to detail while reloading. Here are SIX TIPS that can help you avoid these common mistakes, and build more accurate ammo for your club matches.
1. Align Front Rest and Rear Bags. We see many shooters whose rear bag is angled left or right relative to the bore axis. This can happen when you rush your set-up. But even if you set the gun up carefully, the rear bag can twist due to recoil or the way your arm contacts the bag. After every shot, make sure your rear bag is aligned properly (this is especially important for bag squeezers who may actually pull the bag out of alignment as they squeeze).
Forum member ArtB adds: “To align my front rest and rear bag with the target, I use an old golf club shaft. I run it from my front rest stop through a line that crosses over my speed screw and into the slot between the two ears. I stand behind that set-up and make sure I see a straight line pointing at the target. I also tape a spot on the golf shaft that indicates how far the back end of the rear bag should be placed from the front rest stop. If you don’t have a golf shaft, use a wood dowel.
2. Avoid Contact Interference. We see three common kinds of contact or mechanical interference that can really hurt accuracy. First, if your stock has front and/or rear sling swivels make sure these do NOT contact the front or rear bags at any point of the gun’s travel. When a sling swivel digs into the front bag that can cause a shot to pop high or low. To avoid this, reposition the rifle so the swivels don’t contact the bags or simply remove the swivels before your match. Second, watch out for the rear of the stock grip area. Make sure this is not resting on the bag as you fire and that it can’t come back to contact the bag during recoil. That lip or edge at the bottom of the grip can cause problems when it contacts the rear bag. Third, watch out for the stud or arm on the front rest that limits forward stock travel. With some rests this is high enough that it can actually contact the barrel. We encountered one shooter recently who was complaining about “vertical flyers” during his match. It turns out his barrel was actually hitting the front stop! With most front rests you can either lower the stop or twist the arm to the left or right so it won’t contact the barrel.
3. Weigh Your Charges — Every One. This may sound obvious, but many folks still rely on a powder measure. Yes we know that most short-range BR shooters throw their charges without weighing, but if you’re going to pre-load for a club match there is no reason NOT to weigh your charges. You may be surprised at how inconsistent your powder measure actually is. One of our testers was recently throwing H4198 charges from a Harrell’s measure for his 30BR. Each charge was then weighed twice with a Denver Instrument lab scale. Our tester found that thrown charges varied by up to 0.7 grains! And that’s with a premium measure.
4. Measure Your Loaded Ammo — After Bullet Seating. Even if you’ve checked your brass and bullets prior to assembling your ammo, we recommend that you weigh your loaded rounds and measure them from base of case to bullet ogive using a comparator. If you find a round that is “way off” in weight or more than .005″ off your intended base to ogive length, set it aside and use that round for a fouler. (Note: if the weight is off by more than 6 or 7 grains you may want to disassemble the round and check your powder charge.) With premium, pre-sorted bullets, we’ve found that we can keep 95% of loaded rounds within a range of .002″, measuring from base (of case) to ogive. Now, with some lots of bullets, you just can’t keep things within .002″, but you should still measure each loaded match round to ensure you don’t have some cases that are way too short or way too long.
5. Check Your Fasteners. Before a match you need to double-check your scope rings or iron sight mounts to ensure everything is tight. Likewise, you should check the tension on the screws/bolts that hold the action in place. Even on a low-recoiling rimfire rifle, action screws or scope rings can come loose during normal firing.
6. Make a Checklist and Pack the Night Before. Ever drive 50 miles to a match then discover you have the wrong ammo or that you forgot your bolt? Well, mistakes like that happen to the best of us. You can avoid these oversights (and reduce stress at matches) by making a checklist of all the stuff you need. Organize your firearms, range kit, ammo box, and shooting accessories the night before the match. And, like a good Boy Scout, “be prepared”. Bring a jacket and hat if it might be cold. If you have windflags, bring them (even if you’re not sure the rules allow them). Bring spare batteries, and it’s wise to bring a spare rifle and ammo for it. If you have just one gun, a simple mechanical breakdown (such as a broken firing pin) can ruin your whole weekend.
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Sinclair Internationalhas released an interesting article about Case Concentricity* and bullet “run-out”. This instructional article by Bob Kohl explains the reasons brass can exhibit poor concentricity, and why high bullet run-out can be detrimental to accuracy.
Concentricity, Bullet Alignment, and Accuracyby Bob Kohl
The purpose of loading your own ammo is to minimize all the variables that can affect accuracy and can be controlled with proper and conscientious handloading. Concentricity and bullet run-out are important when you’re loading for accuracy. Ideally, it’s important to strive to make each round the same as the one before it and the one after it. It’s a simple issue of uniformity.
The reason shooters work with tools and gauges to measure and control concentricity is simple: to make sure the bullet starts down the bore consistently in line with the bore. If the case isn’t properly concentric and the bullet isn’t properly aligned down the center of the bore, the bullet will enter the rifling inconsistently. While the bore might force the bullet to align itself with the bore (but normally it doesn’t), the bullet may be damaged or overstressed in the process – if it even it corrects itself in transit. These are issues we strive to remedy by handloading, to maintain the best standard possible for accurate ammunition.
The term “concentricity” is derived from “concentric circle”. In simple terms it’s the issue of having the outside of the cartridge in a concentric circle around the center. That goes from case head and center of the flash hole, to the tip of the bullet.
Factors Affecting Concentricity
The point of using this term is to identify a series of issues that affect accurate ammunition. Ideally this would work best with a straight-walled case; but since most rifle cartridge cases are tapered, it equates to the smallest cross section that can be measured point by point to verify the concentric circle around the center. For the examples below, I’m working with .308 Winchester ammo.
Figure 1: The cartridge.
Figure 2: Centerline axis of the case, extending from flash hole to case mouth.
The case walls have to be in perfect alignment with the center, or axis, of that case, even if it’s measured at a thousandth of an inch per segment (in a tapered case).
Figure 3: Case body in alignment with its axis, or centerline, even in a tapered case.
The case neck must also be in alignment with its axis. By not doing so you can have erratic bullet entry into the bore. The case neck wall itself should be as uniform as possible in alignment and in thickness (see the M80 7.62x51mm NATO cartridge in Figure 5) and brass can change its alignment and shape. It’s why we expand the case neck or while some folks ream the inside of the neck and then turn the outside for consistent thickness, which affects the tension on the bullet when seated.
Figure 4: Neck in alignment with center of the case axis.
Figure 5: Variations in case neck wall thickness, especially on some military brass, can cause an offset of the bullet in its alignment. This is an M80 ball round. Note the distinct difference of the neck walls.
Having a ball micrometer on hand helps, especially with military brass like 7.62x51mm in a semi-auto rifle, where there are limits as to how thin you want the neck walls to be. In the case of 7.62 ball brass you want to keep the wall to .0145″.
Figure 6: A ball micrometer like this RCBS tool (#100-010-268) can measure case neck thickness.
Turning the outside of the neck wall is important with .308 military cases regardless of whether you expand or ream the neck walls. There are several outside neck turning tools from Forster, Hornady, Sinclair, and others. I’ve been using classic Forster case trimming (#100-203-301) and neck turning (#749-012-890) tools for 40 years.
The cartridge, after being loaded, still needs to be in alignment with the center of the case axis. Figure 7 shows a bad example of this, a round of M80 ball. A tilted bullet is measured for what’s known as bullet “run-out”.
Figure 7: An M80 round with the bullet tilted and not aligned with the axis. This will be a flyer!
Run-out can be affected by several things: (1) improperly indexing your case while sizing, which includes not using the proper shell holder, especially while using a normal expander ball on the sizing die (it also can stretch the brass). (2) The head of a turret press can flex; and (3) improper or sloppy bullet seating. This is also relevant when it comes to using a progressive press when trying to load accuracy ammo.
Mid Tompkins came up with a simple solution for better bullet seating years ago. Seat your bullet half way into the case, back off the seater die and rotate the case 180 degrees before you finish seating the bullet. It cuts down on run-out problems, especially with military brass. You also want to gently ream the inside of the neck mouth to keep from having any brass mar the surface of the bullet jacket and make proper seating easier. A tilted bullet often means a flyer.
Figure 8: Proper alignment from the center of the case head to the tip of the bullet.
*Actually some folks would say that if we are talking about things being off-center or out-of-round, we are actually talking about “eccentricity”. But the tools we use are called “Concentricity Guages” and Concentricity is the term most commonly used when discussing this subject.
Story Tip from EdLongrange. We welcome reader submissions.
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New handloaders often ask us for advice on reloading techniques and equipment selection. It’s always best for novice reloaders to work under the guidance of an experienced mentor. Nothing beats “learning the ropes” with an experienced reloader at ones side. In addition, new handloaders should acquire one or more good reloading manuals, such as the Hornady Reloading Handbook (9th Ed.). We recommend reading the introductory chapters of a reloading manual to get a good understanding of the basic principles involved.
Along with print manuals, instructional DVDs are available. RCBS sells a 32-minute, step-by-step Precisioneered Handloading DVD, narrated by Shooting USA’s Jim Scoutten. This $9.19 DVD covers the basics of metallic cartridge reloading and shotshell reloading.
For those who have already mastered the basics, Redding offers a 45-minute instructional DVD, appropriately named Advanced Handloading: Beyond The Basics ($17.52 at Amazon.com). The Redding DVD, produced with help from Sierra Bullets, is narrated by John Barsness, field editor of Rifle and Handloader magazines. The Redding DVD does go “Beyond the Basics” but it really is more an intermediate resource — it doesn’t reveal some of the most sophisticated methods of case prep and load tuning used by competitive benchrest shooters. Nonetheless it is a good resource for those getting started with rifle cartridge reloading.
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