Developing a Load for Competition Shooting, Part 1
Over the years, we have heard or read just about every method used by shooter/reloaders to work up an optimum load for their rifles. It seems like every shooter has their own method that works for them. That said, there has to be a more scientific approach to the problem. One that works for everyone and is based on a repeatable and testable procedure that results in the best accuracy for your rifle.
In the past, reloaders talked with each other and read the reloading manuals in an effort to determine the most accurate load for their bullet. We loaded them up and went to the range for testing. Sometimes it worked, sometimes it didn’t. When it didn’t, we went back to the reloading bench to load up some more cases.
The method outlined in this article was suggested to us by John Dink, a world class shooter from Albuquerque, New Mexico. John’s scientific approach to reloading and shooting is the best way to insure top performance from your equipment. However, it only works if your rifle is built right. In other words, a precision target rifle, not a mass-produced assembly line gun.
We won’t include brass preparation in this article, leaving that for a later date. Here, we will focus on how to logically and methodically work up and select the best load for a given rifle/bullet/powder combination. We will use the 6mm BR (.243) caliber as our example. For the record, it was a real test, as we were using a new bullet and powder. As such, we didn’t know what load would shoot at a competitive level.
Step 1: Select the weight and type bullet you want to reload. We chose the Berger 105 grain VLD bullet. The K-P barrel on our 6BR really “likes” Berger bullets. Not to mention that they have superb ballistic coefficients. All bullets are not created equal. Variations in the ogive profile of Berger, Sierra, JLK bullets and others guarantees that bullets of the same weight will behave differently in different guns, even with the same powder charge. As such, you will need to repeat this test every time you change bullets, powder and guns.
Step 2: Select a powder that has been tested by other shooters as working best for your caliber, bullet weight and bullet manufacturer. This requires some research, but it’s not very difficult. There are several good sources for this information including internet sites, reloading manuals and shooters reference books. In the 6mm BR, the most commonly recommended powders include Hodgdon’s Varget, Vihtavuori N540, IMR 4007ssc and Alliant RL 15. We chose Hodgdon’s Varget, as it is almost the “standard” for the 6BR.
Step 3: Determine the powder load range for your bullet weight that has resulted in accurate loads in other folk’s rifles. We determined that the common range was from 29.2 grains to 30.4 grains.
Step 4: Load three rounds each, starting at each of the following charges: 29.2 grains, 29.6 grains, 30.0 grains, 30.4 grains. The 0.4 grain spread will produce a respectable comparison of loads. Take them to the range and test fire them across a chronograph. We know the average shooter doesn’t have a chronograph, but you should. We went for 40 years without one. It was hard to justify a $400 - $500 piece of equipment in the family budget that would be only used a couple of times a year. However, chronograph prices have come down, thanks to solid state electronics. They are available from $120 to $250 from suppliers such as Sinclair International, Midway USA and Sportsman’s Warehouse.
You will get no argument from us that the “high end” CED M2 Chronograph is as good as it gets. However, for the average person, a Chrony Alpha Master at $120 will do fine. The latter was purchased by our daughter as a father’s day present for Jim. He finds it easy to use, reliable and very compact (it folds up). However, be aware that there is a saying in the shooting community that there are two kinds of people, those that have shot their chrony and those that will someday shoot their chrony. At present, we are in the last category. In other words, you must be very careful in shooting through the upright sensors, remembering that a scoped rifle will shoot about 2” low at the 10 to 15 foot distance at which your chronograph is positioned. Hit the base and you will see the full effect of a high power round impacting a precision instrument!
The following table displays the three shot velocities for the charges we loaded:
Varget Powder 29.2gn 29.6gn 30.0gn 30.4gn
2738 fps 2857 fps 2889 fps 2905 fps
2826 fps 2867 fps 2900 fps 2945 fps
2792 fps 2863 fps 2898 fps 2920 fps
Average: 2785 fps 2862 fps 2896 fps 2923 fps
Std Dev: 44 fps 5 fps 6 fps 20 fps
Obviously, a sample size of three does not yield a statistically significant standard deviation. However, it does give us an indication as to the consistency of velocity for each load. If we were to guess at this point, as to which load would be the best, our money would be on either the 29.6 or 30.0 grain loads. However, don’t make that assumption and stop your testing.
Step 5: Due to the fact that most 6BR's prefer loads above 2800 fps, we excluded the 29.2 grain load from further testing. Load ten rounds each of the other three charges. Go to the range, set your target up at 200 yards and fire each, without making windage or elevation adjustments to your scope (after you get on paper, of course). If all goes well, you will see a somewhat circular (scatter) pattern on loads that are on either side of your optimum load. The windage and elevation will “close up” toward center with your best load. You can’t get this kind of data with the three round or five round groups that most shooters use.
Step 6: Analyze the three targets, measure the spread (vertical and windage). You are looking for the load that gives you ½ “MOA vertical, or less, at 200 yards. Our results are shown below. The winner was 30.0 grains of Varget behind the Berger 105 VLD bullet. That is a half inch group, ¼” MOA at 200 yards. You gotta love the 6BR, it makes everyone a hero! However, using a Nightforce NXS 12-42x56 scope sure helps.
6BR load development test targets. Photo by Jim Clary.
The average shooter might burn over 100 rounds to get (hopefully) the same results. The method outlined in this article requires less than 50 rounds to obtain great results. If your 200 yard test group isn’t as tight as ours, you might decide to tweak the load by +/-0.2 grains. However, we decided to take our results and shoot with them.
Once you have determined the optimum load for your rifle, plug the velocity information from the chronograph into a ballistic program to account for all the other factors that impact your shooting. The question now is, how does the load shoot at long range?
Two days after our test, we traveled to Capitan, NM for a Palma match to get some practice. The winds were nasty, but Susannah shot a 149/150 at 800 yards. Not perfect, but good enough to convince us that the load was right for that rifle with the Berger bullet and Varget powder.
As a side note, the Nightforce ballistic program “called” for an elevation adjustment of 14.00 MOA for 800 yards. Her first sighter shot was a nine (9) and the second was a ten (10), so she went for record. That just about says it all for John’s load development method as well as the accuracy of the Nightforce ballistic program, which was written by Gerald Perry.
Finally, we would like to remind everyone of the words of Brad Sauve, U.S. National Champion F-TR shooter (2004, 2006 and 2007): “Spend more time shooting than loading “perfect” ammunition or cleaning. Squeezing the last ¼” out of your groups won’t do you any good if you can’t hold one MOA or you can’t read wind conditions.”
Copyright 2008 by Dr. Jim Clary. All rights reserved.