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July 27th, 2012
 How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which long-term test results are lacking.
Is there a more reliable way to predict barrel life — one that will work for a broad range of calibers? Well, Forum member MikeCr has developed an Excel spreadsheet that accounts for a number of variables, and gives a pretty good estimate of useful barrel life, whether you’re shooting a .223 Rem or a 338 Lapua Magnum. Mike’s program predicts barrel life using five variables: 1) Bullet Diameter; 2) Powder Charge weight; 3) Powder Heat Potential (KJ/kg); 4) Pressure (in psi); and 5) Bullet Coating (yes/no). Mike provides a table with Heat Potential ratings for most popular powder types. The user needs to know the pressure of his load. This can be estimated with QuickLOAD.
You can download the lastest version of Mike’s spreadsheet below. You’ll need Excel or an Excel viewer to open the file.
Click to Download Spreadsheet: Barrel Life Spreadsheet (Latest Version)
Shown below is Mike’s Spreadsheet, with variables for a 6BR shooting 105gr “naked” bullets with 30.3 grains of Hodgdon Varget powder. The formula predicts 2401 rounds of barrel life. That corresponds pretty well to what we’d expect for a 6BR — about 2500 rounds.
 
Mike observes: “There has been alot of discussion lately related to cartridge design and resulting barrel life. This is a really important factor to consider amongst a myriad of choices. Barrel life is controversial, and subjective. There are no clear-cut standards for comparison. But a few years ago, I put together a spreadsheet based on Bart Bobbit’s rule of thumb. It worked pretty good, only occasionally failing some tests when validated against posted barrel lives.
According to Ken Howell, I had to account for pressure. And Henry Child’s powder temperature testing provided another piece needed. So, I’ve tweaked it here and there to pass more tests. From 223rem to 300 UltraMagnum. Another element added, but turned off is shot interval. I would need way more tests to lock in on this. But everyone knows, the faster you shoot, the worse the barrel life.
Anyway, another factor hard to define is ‘accurate’ barrel life. This cannot be quantified without standards. Barrels are replaced when expectations are no longer met. I feel that a [barrel] passes peak potential in a finite period due to throat erosion. But that don’t mean it’s toast, if it still shoots well enough. It’s just as likely that many of us never see that peak potential anyway. It’s a slippery thing. Point-blank BR competitors will toss a barrel when it leaves the 1s. I could get another 4000 rounds from it, and be content with its performance, I’m sure.”
NOTE: Mike says: “This spreadsheet may show a lower barrel life than you prefer. But it pretty well spotlights cartridges to stay away from if you plan much time at the range or in dog town.”
Editor’s Comment: We want to stress that Mike’s spreadsheet is a helpful tool, but it is not a definitive “take-it-to-the-bank” indicator of barrel life. Mike cautions that predicting barrel life involves so many different factors (including how hot the barrel is run), that the task is a bit like predicting tread life on car tires. Still, the spreadsheet is very helpful. It can certainly put shooters on notice that some chamberings (such as the 6-284) are likely to be a barrel burners. That can help you make a smart decision when choosing a chambering for your next rifle.
July 11th, 2012
Report by Birdog
Forum member John S. aka “Voldoc”, came over Sunday to check the elevation come-ups on his new March scope. At my home range, dubbed the ‘Dasher Dome’, we had either a gong or paper target at 100-yard intervals to 800 yards. Voldoc wanted to check his ballistic chart against real world conditions. Voldoc will use this test to verify his come-ups for a “quick-view” BDC tape that will be applied to his elevation turret. He was running his “go to”, tried and true “red mist load”, an 87gr Hornady V-Max. The rifle was a Nesika-action 6mm Dasher with 1:12″-twist HV-contour Krieger. Doc has doubles with this combination out to 700 yards and many kills past 1,000. [Editor’s Note: We featured Voldoc’s varmint rifles in our Tennessee Triple Threat story, a Gun of the Week article on this site. Notably, Voldoc made a 1,000-yard plus prarie dog kill with a 20BR shooting 55gr Bergers.]
My ‘Dasher Dome’ is a good place for testing. Dirt berms have just been completed at 100, 300, 600, 700, an 780 yards. Voldoc started at 100 and shot at 100-yard intervals recording his elevation at each interval. His ballistic chart was within a click or two at each distance. When he reached 780 yards, he repeated the test at each distance down to 300 yards. Dead on!
 Custom BDC Turret Tapes
Doc already has ballistics tapes fitted to his Nightforce-equipped rigs. But Doc’s new Dasher has a March so he need to confirm the come-ups. The tapes, made by Forum member Dominic (aka “Xterminator”), show rotation clicks for various yardages. There are versions for both standard and “High-Speed” Nightforce turrets, as well as some other scope brands. For more info, send email to: media-banc [at] videotron.ca . Learn more about Dominic’s custom come-up tapes in this Forum Thread.
| Doc at the ‘Dome’
Confirmed results at 780 yards
Sub-Quarter MOA group on Steel Prairie Dog
The photo at right confirms that VolDoc has his zeroes confirmed at 780 yards. Look closely. That’s about a 1.5″ center-mass group on ‘Chico’ the prairie dog (lower right). Nice Shooting Doc! Chico’s buddy, ‘Chuckie’ the steel ground-hog, took many hits. Show in photo are three hits in the throat zone.
Good Friends, Good Rifles Make for the Best of Times
Birdog reports: “Overall, this was a great way to spent a Sunday. Temps reached 103° F, but Doc got to the ‘Dasher Dome’ at 5:30 a.m. and we beat the heat. After testing was completed, we walked two miles with temps in the 90s. What can I say — good friends, good BRs — this was the best of times! |
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Serious Rangefinders:
Very high-quality laser rangefinders permitted the shooters to confirm target distances with great precision. Birdog uses a Vectronix LRF while Voldoc uses a Leica GeoVid rangefinding binoculars.
June 17th, 2012
 How to Avoid Shooting your Chrono: There is nothing more frustrating (or embarassing) than sending a live round into your expensive new Chronograph. When setting up a chrono, we always first remove the bolt and bore-sight to ensure that the path of the bullet is not too low. When bore-sighting visually, set up the rifle securely on the sandbags and look through the bore, breech to muzzle, lining up the barrel with your aim point on the target. Then (during an appropriate cease-fire), walk behind the chronograph. Looking straight back through the “V” formed by the sky-screens, you should be able to see light at the end of the barrel if the gun is positioned correctly.
Adjust the height, angle and horizontal position of the chronograph so the bullet will pass through the middle of the “V” below the sky-screens, no less than 5″ above the light sensors. We put tape 5″ up on the front sky-screen supports to make it easy to align the bore to the right height over the light sensors. Make sure the chrono housing is parallel to the path of the bullet. Don’t worry if the unit is not parallel to the ground surface. What you want is the bullet to pass over both front and rear sensors at the same height. Don’t try to set the chrono height in reference to the lens of your scope–as it sits 1″ to 2″ above your bore axis. To avoid muzzle blast interference, set your chronograph at least 10 feet from the end of the muzzle (or the distance recommended by the manufacturer).
IRON SIGHT Rifles: A common mistake, particularly with newbie AR15 shooters, is to use the iron sights when setting the height of the chronograph. All too often, people forget that AR sights are positioned roughly 2.4″ above the bore axis (at the top of the front sight blade). If you set your bullet pass-through point using your AR’s front sight, the bullet will actually be traveling 2.4″ lower as it goes through the chrono. That’s why we recommend bore-sighting and setting the bullet travel point about 5-8″ above the base of the sky-screen support shafts. (Or the vertical distance the chronograph maker otherwise recommends).
TARGET AIM POINT: When doing chrono work, we suggest you shoot at a single aiming point no more than 2″ in diameter (on your target paper). Use that aiming point when aligning your chrono with your rifle’s bore. If you use a 2″ bright orange dot, you should be able to see that through the bore at 100 yards. Using a single 2″ target reduces the chance of a screen hit as you shift points of aim. If you shoot at multiple target dots, place them in a vertical line, and bore sight on the lowest dot. Always set your chron height to set safe clearance for the LOWEST target dot, and then work upwards only.
June 3rd, 2012
Building your own portable shooting bench is a great winter do-it-yourself project. You can build a sturdy bench for well under $100 in materials. Compare that to some deluxe factory-built benches which may cost $450.00 or more.
A wide assortment of home-built shooting bench designs have been featured on the internet. Renovation Headquarters has put together a web page with plans for eleven (11) different shooting benches. Each bench is illustrated with a photo and link to FREE Plans and building instructions. You’ll find all-wood designs as well as benches that combine a wood top with a metal sub-frame or legs.
CLICK HERE for Shooting Bench FREE Plans Webpage
Among Renovation HQ’s eleven featured shooting benches, here are four designs we liked:
April 17th, 2012
Shaving bullet jackets is a problem reloaders encounter from time to time. It can be caused by excessive neck tension, burrs on the case mouth, or over-aggressive chamfering that leaves a ragged edge on the case mouth. Larry Medler discovered some rounds where the bullet jackets were getting shaved. Diagnosing the problem, he found that this was caused by his outside neck chamfer. He was using a powered screwdriver to rotate the case, and over-cutting plus tool chatter was causing the case neck to roll inwards. This created a thin, sharp edge that actually cut into the bullet jacket as the bullet was being seated.
 
Larry has a Load Force 250 measuring instrument that records the dynamic bullet seating force and displays the results on a computer screen. Larry noted that spikes in seating force were associated with the cases where the bullets were shaved. Inspecting the cases, Larry realized what was happening. Chamfering the outside after doing the inside allowed his tools to cut too much. Combined with tool chatter, this actually created a sharp, ragged edge that rolled inward towards the bullet: “I discovered I had rolled the case mouth rim inward while deburring the outer edge. When deburring the case mouth on the outside edge, every now and then I could hear some tool chatter. The effects of this chatter really show in the picture.”
The above chart shows the dynamic bullet seating force for the bullet with the shaved jacket. Note the large initial force used to cut and scratch the bullet outer surfaces. The final seating force of 47 pounds is just before the Wilson Seating Die bottoms out and the force on the load cell jumps. The chart below shows normal bullet seating force.
As a fix, Larry decided to reverse the neck deburring operations. Now he deburrs the outside first. This reduces tool chatter and prevents the edge from rolling over, because the neck thickness has not been thinned by inside chamfering. While Larry uses a powered screwdriver to speed his case processing, the lesson applies to those who chamfer manually as well–do the outside first and never overcut.
Remember, you simply want to remove burrs and create a slight chamfer. You don’t want to thin the brass significantly at the case mouth. This is why it is important to be very careful when using a deep-angle cutter such as the K&M inside neck chamferer. Click HERE to read Larry’s full report on neck chamfering, with more details on use of the Load Force 250 measuring instrument. Using device such as this, or a K&M arbor press equipped with a seating force gauge, will help you diagnose problems with your neck tension and reloading procedures.
April 8th, 2012
 Forum member Ed L. (aka itchyTF) owns one of the beautifully-crafted SEB NEO front joystick rests. These units are in short supply — creator Seb Lambang can’t keep up with demand. Anyone lucky enough to own a SEB NEO would naturally would want to keep it in perfect condition, and Ed is no exception. Ed put together a system to cradle and protect his SEB NEO during transport and storage. Ed tells us: “I decided to give my NEO its own home. I only wanted to remove the leg before storage so I decided on an empty Pelican Storm IM2450 case and added my own foam. This IM2450 case is a little wider than it needs to be, but I couldn’t find anything closer and still fit the other dimensions. The blue and white foam is more rigid than the typical gray foam. The Allen wrenches are placed in the rear piece of white foam.”
Ed found the Pelican Storm IM2450 case on the internet for $103 with free shipping. This same case is sold as the Hardigg IM2450 Storm Case. All-up weight, with the SEB NEO rest in the case, is 32 pounds. CLICK Thumbnails below to view larger images.
March 29th, 2012
Three-gun match competitor Zak Smith employs a simple, handy means to store his elevation and wind dift data — a laminated data card. To make one, first generate a come-up table, using one of the free online ballistics programs such as JBM Ballistics. You can also put the information in an Excel spreadsheet or MS Word table and print it out. You want to keep it pretty small.
Below is a sample of a data card. For each distance, the card includes drop in inches, drop in MOA, drop in mils. It also shows drift for a 10-mph cross wind, expressed three ways–inches, MOA, and mils. Zak explained that “to save space… I printed data every 50 yards. For an actual data-card, I recommend printing data every 20 or 25 yards.” But Zak also advised that you’ll want to customize the card format to keep things simple: “The sample card has multiple sets of data to be more universal. But if you make your own data card, you can reduce the chance of a mistake by keeping it simple. Because I use scopes with MILS, my own card (photo below left) just has three items: range, wind, drop in MILS only.”
 
Once you have the card you can fold it in half and then have it laminated at a local office store or Kinko’s. You can keep this in your pocket, tape it to your stock, or tie the laminated card to your rifle. If you regularly shoot at both low and high elevations, you may want to create multiple cards (since your ballistics change with altitude). To learn more about ballistic tables and data cards, check out the excellent “Practical Long-Range Rifle Shooting–Part 1″ article on Zak’s website. This article offers many other insights as well–including valuable tips on caliber and rifle selection.
Scope-Cover Mounted Ballistics Table
 Another option is to place your ballistics card on the back of the front flip-up scope cover. This set-up is used by Forum member Greg C. (aka “Rem40X”). With your ‘come-up’ table on the flip-up cover you can check your windage and elevation drops easily without having to move out of shooting position. Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit. And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”
Updated Links for JBM Ballistics Program
With the release of version 5.1 of the JBM program, some URLs for the calculations pages have changed. You may want to update your bookmarks with the following web addresses:
March 10th, 2012
 Here’s a tip that can help you score higher at matches and get more predictable results when weighing loads with an electronic scale. Kelly Bachand, a top prone shooter and electrical engineering major at the Univ. of Washington, tells us that all digital scales can drift. Therefore Kelly recommends re-calibrating electronic scales often. In addition — and this is key — Kelly recommends that you shoot the ammo in the exact order in which it was loaded. Arrange your loaded ammo in a box in the order of loading and shoot it first-loaded to last-loaded. (Or, if you prefer, shoot it last-loaded to first-loaded.) The important thing is to maintain the order and not mix everything up. That way, if your scale drifts, the effect of drift on charge weight will be incremental from one loaded round to the next, so point of impact change should be negligible. Conversely, if you shoot your last-loaded round right after your first-loaded round, the effect of scale drift is at its maximum, so powder charge varience is maximized. And that can produce a different point of impact (POI) on the target.
Tips on Loading with Electronic Scales
by Kelly Bachand
If you use a digital scale to measure powder charges, recalibrate the scale often. I like to do this about every 25 rounds or so. Additionally, most electronic scales rely on eddy currents for their precision. Eddy currents are easily disrupted by static electricity so keep a cloth or ground strap nearby to remove any static currents should the scale start acting up; I usually just use a fabric softener sheet that has gone through the dryer once.
Shoot Ammo in Order of Loading
I shoot my rounds in the same order or reverse order as I load them. If the charge weight varies due to scale drift during use, the difference will be gradual if I shoot in the same order as production (or reverse order). I should be able to adjust for the slight varience in charge weight without having any wildly high or low shots (see the charts below for a graphical demonstration). I usually load my ammunition just 100 rounds at a time. Give yourself plenty of time and remember that you will make your best ammunition when you are fully awake and alert.
This graph demonstrates the effect a .01% (that’s 1/100th of 1 percent) difference in scale measurement would have over the course of 100 rounds assuming the desired load is somewhere between 46 and 47 grains. The final round made would have almost 1% less (or more) powder than the first, that’s almost an 0.5 grain difference from the first. If shot back to back, these rounds will invariably have different points of impact on the target.
This graph demonstrates the same .01% difference in scale measurement but this time with a recalibration every 25 rounds. By recalibrating the scale every 25 rounds the furthest a weighed charge ever gets from the original is less than 0.25%. Again if the charge being weighed is between 46 and 47 grains then the 26th round made would vary from the 1st by .12 grains. Even that small difference would likely show on target.
Either way it is important to note that if the bullets are shot in the same (or reverse) order as they are made, the biggest difference from bullet to bullet in this example is less than .01 grains.
March 6th, 2012
 We are often asked: “What size neck bushing is best for Lapua 6mmBR brass in a ‘no-turn’ chamber?” The questioner planned to purchase a Redding Type ‘S’ full-length sizing die with neck bushings. The quick answer is that one should probably get both 0.265 and 0.266 bushings and see what works best. With the current “blue box” Lapua brass, a loaded 6BR round with an unturned neck will typically run about 0.268″ (depending on the bullet). A 0.266″ neck bushing, after springback, will give about 0.0015″ tension which can work well in a bolt gun. In a gas gun, we recommend running .003″ (or more) neck tension.
Alternative to Bushings — Honed Full-Length dies
Conventional, non-bushing full-length sizing dies can create ultra-accurate ammo with very low run-out. For some applications, we prefer a non-bushing FL die over a bushing die — so long as the neck tension is correct. But many FL dies have an undersized neck diameter so you end up with excess neck tension, and you work the brass excessively. Forster offers a simple, inexpensive solution — honing the neck diameter to whatever size you want.
If you purchase a Forster non-bushing, full-length sizing die, Forster will hone the neck dimension to your specs for about $10.00 extra. This way you can have a FL die that provides the right amount of tension for your particular load. Forster dies are relatively inexpensive so you can afford to have a couple of FL dies with necks honed to different diameters — such as 0.265″ and 0.266″ for a no-turn 6mmBR. The die itself is very affordable — currently Sinclair Int’l charges $33.95 for a Forster 6mmBR full-length sizing die (item FP6BRFL).
Forster FL dies, necks honed to .265″, .266″, and .267″.
Steve Rasmussen of IowaHighPower.com gave this a try. In fact, he had three dies made — each with a different neck dimension. Here’s his report: “My original Forster 6BR FL die sized the necks down a lot, less than 0.260″, .256″ if I recall correctly. I sent my die in and asked if they could supply two more FL dies (for three total) to have the necks honed to 0.265″, 0.266″, and 0.267″. The cost was $10 for my supplied die and $38.50 plus $10.00 honing fee for each additional die. Return shipping was $11.00 via USPS Priority Mail.”
The table below shows the neck diameter range of ten (10) sized cases using each die. Brass springback after sizing runs 1 to 1.3 thousandths. Steve was using the older, “brown box” Lapua brass with thicker necks so he needed the .267″ bushing. The older Lapua 6mmBR brass measures about 0.2695″ with bullet in place. Steve explained: “My loaded rounds are running 0.2697-0.2699 using [brown box] Lapua 6BR brass. So far the dies are working well. I sized 80 cases with the 0.266″ necked die. The shoulder is running 0.4582″ and 0.300″ up from the base is 0.4684″. I spun 20 of ‘em and 16 had a runout of one thousandth (0.001) and the other 4 at 1.5 thousandths (0.0015).” That shows that these honed Forster FL dies produce exceptionally straight sized cases.
| Die Diameter |
Sized Brass |
Springback |
Neck Tension |
| 0.267 Die |
0.2683-0.2684 |
0.0013 |
0.0014 |
| 0.266 Die |
0.2672-0.2674 |
0.0013 |
0.0025 |
| 0.265 Die |
0.2659-0.2660 |
0.0010 |
0.0039 |
February 24th, 2012
 Larry Racine is a respected gunsmith based in New Hampshire. He is also a two-time member of the U.S. Palma Team, and a five-time New Hampshire State Highpower rifle champion. Larry, who runs LPR Gunsmithing, has developed a brilliantly simple means of switching rifle barrels with an ordinary spanner or open-end wrench. With this set-up you can switch barrels in the field in seconds without the need for a barrel vice.
For most barrels, Larry mills a hex with six flats on the end of the barrel. This allows a shooter to change barrels quickly at home or on the line with a simple box-head wrench or a socket wrench. Larry says: “You don’t even have to take the barreled action out of the gun. Just set the buttstock on the ground, between your feet, put a wrench on it, hit it with the palm of your hand — and off comes the barrel.” For barrels fitted with a muzzle brake, Larry has a slightly different system. He mills two flats behind the brake so you can use an open-end wrench to do the job.
With either a hex on the end, or two flats for a brake-equipped rifle, the system works with any medium- to heavy-contour barrel with a muzzle-diameter of at least 0.700″. This will even work for high-power rigs using clamp-on sights or bloop tubes. Larry explains: “A lot of us here in New England use clamp-on front sights. The barrel will be turned to 0.750 for the sight, with the hex on the end. A bloop tube can go right over the end, no problem.”
Larry has used this system over the past few years to win a number of matches. In one 600-yard 3 by 20 prone match, Larry used three different barrels, with three different chamberings, on the same Savage rifle. Larry changed the barrels on the line.
Larry was able to do this because the system has little to no loss of zero from one installation of a given barrel to the next installation of that barrel. This lets the shooter start the match with confidence that the first sighter will be on paper. Larry reports that the simple system works great: “To date we have used this system on Savage, Remington, Winchester, RPA, and Nesika actions.”
Racine’s system is very affordable. If Larry does the chamber work on your barrel he charges $45.00 extra to mill a hex or two flats on your barrel. If you only want the hex or flats done, Larry charges $55.00. For more info, visit LPRGunsmith.com or call Larry at (603) 357-0055.
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