Fundamentals of Muzzleloader Accuracy
Accuracy, or the promise of accuracy, has long dominated the muzzleloading ad hyperbole. There are fundamental reasons why good accuracy is achieved, and reasons why it is not. What we know is that consistency and accuracy are synonyms. Not a new premise at all, consistency throughout our muzzleloading system promotes repeatable accuracy, the only accuracy worth repeating.
It begins with rifles that are consistent, of course. Barrels must have consistent rates of twist and consistent rifling depth. If they don’t, problems may arise that are hard to discern. It is one of the reasons why the answer to “how come my muzzleloader won’t shoot?” is often unanswerable. Few consumers have any way of telling if their rifle begins as a 1:27 rate of twist, only to end at the muzzle as a 1:30. Few of us air-gage our own barrels, or have any way to detect rifling depth anomalies in the center of the barrel.
To quote Dan Lilja, "There are some obvious mechanical attributes that a barrel should possess if it is going to be a 'tack-driver.' These include the straightness of the hole, uniformity of the rifling geometry and the twist rate. If the width of the lands or the depth of the grooves varies, that barrel is never going to shoot accurately."
There is natural tooling wear in the manufacture of a barrel. Tooling is expensive, of course, as is quality control. The cost of tooling, scrap rates, and inspection during the manufacturing process is not something that is visible just by looking at a gun. Some manufacturers don’t dare publish their tolerances, and are reticent to tell you if they use certified materials or not. It is important, of course, as gun barrel metal varies lot by lot. It does not react to reaming and rifling identically when you just arbitrarily change lots of metals. Ordering certified materials takes time and money, of course. Quality manufacturers do this; unscrupulous manufacturers do not bother. Barrel-action to stock rigidity is a fundamental concept of accuracy. If you have a barreled action moving around inside its stock, repeatable accuracy is a great deal harder to find. We don’t have to look very far to find clear evidence of this: single shot bolt action rifles rule the competition world, where break actions are nowhere to be found, considered not remotely competitive by long range shooters, custom riflesmiths and custom barrel-makers alike.
Laminated stocks are more rigid than others, as they are formed under high heat and high pressure with glue. Laminated stocks promote accuracy due to their rigidity, being far stronger than most of their plastic counterparts out there. Please don’t confuse many “composite” (composite of what?) stocks with McMillan fiberglass stocks and other higher quality options. They are not remotely comparable. Repeatable accuracy is also related to barreled action to stock fit, the basis of hand-bedding. Properly done, bedding can only help accuracy, not hurt it. It, of course, is no automatic compensation for barrel quality or any other of the components of accuracy; it can help only to the extent of preventing barreled action movement that is pre-existing. With a good fit of stock to action, no visible improvement may be seen, as our tests have uncovered.
Some of the other considerations promoting accuracy are more obvious: if your trigger hampers your clean release, it makes your rifle harder to shoot well. The gun itself is no more or less accurate, naturally, but we certainly are. It should go without saying, but seldom does that the reticle of your scope must return to the exact same point after every recoil pulse. If it doesn’t, any other work we put towards striving for repeatable accuracy may be completely lost. The same goes for the lock-time of our actions. Exposed hammers are notoriously slow and those conversant with the fine points of firearms know the value of fast locktime actions. Like a lot of things, it does not change what your rifle is capable of, but it clearly does change what the shooter is capable of.
Primers have had very little effect on velocity variations or accuracy in modern 209 fired muzzleloaders. This is for good reason; the breechplug acts as a throttle body to direct the components of a 209 primer that initiate combustion (primarily hot gas, the particulate matter it contains, gas temperature and gas volume). Regular 209 shotshell primers have an ample supply of both to light off muzzleloading propellants. Your breechplug condition, however, does affect accuracy. All breechplugs erode, even after 100 to 150 shots. Change the throttle body and you have changed the combustion cycle. Many accuracy problems can be addressed just be replacing or cleaning a breechplug.
When it comes to propellant, consistency again means accuracy. Pellets and sticks are by far the worst. All we have to do is weigh them, and multiply the variation by two or three and it become obvious that they are a huge barrier to repeatable accuracy. Sadly, even if you have a consistent propellant, pre-forming them into inconsistent charge weights can destroy accuracy. It only gets worse if the pellets are from open packs and allowed to attract moisture. It is also problematic if pellets or sticks are crushed or shaved during loading. A consistent combustion sequence quickly becomes a practical impossibility. Avoiding preformed anything is as good as accuracy advice as anyone can muster.
Projectiles, of course, need to be consistent if accuracy is a goal. “Match-grade” muzzleloading projectiles are not generally available, nor are match-grade bullets. That said, projectile choices are critical when accuracy is a consideration. As a generality, saboted projectiles offer both accuracy and external ballistic benefits that make them an easy choice over under-bore bullets (“conicals”) that have a propensity to rattle down your bore. There are exceptions, of course, but shooting a bullet without a sabot is akin to shooting a patch and ball, but without the patch. A patch is, of course, a sabot. They both exist for identical purposes. Modern sabot materials are far more durable than cotton, naturally, providing better seals, able to tolerate faster rate of twist barrels, higher peak pressures, higher heat and higher velocities with accuracy. That’s a very good thing, of course. Sabots need no special storage requirements, except to be kept out of direct sunlight, as ultraviolet light degrades them.
Consistency and accuracy remain synonyms. If you are dressing your own sabots, use bullets from the same lot number (some even sort by weight). Throw out any “sabots of mystery,” using only fresh and current formulation sabots direct from MMP. Use bullets that are precision made and have flat bases. The larger the launching platform, the less sabot stress and strain there has to be. That’s why flat base .451, .452 or .458 inch diameter bullets so often shoot better than .429 (“44 caliber”) options.
Use powder and primers from the same lot number. Charges by actual weight remain the most consistent and the most accurate. When working up a load, work up, not down. Always start low and work up. Throwing in a 120 grain by volume charge to start with, for example, may not only be a waste of time but may lead you to believe that a powder/bullet combination is unsuitable, when it actually is one of the best combinations with 90 to 100 grains of powder by volume.This is the area where you get better velocity benefit per grain from your powder charge, rather than simply blowing it out your muzzle.
There is no substitute for geometry, a saboted bullet needs to fit your barrel properly. You shouldn’t need a hydraulic press to load your muzzleloader, but neither should your sabot just drop down the barrel. This, of course, is a matter of trial and error. Your “.50 caliber barrel” may actually be .498 or .499 land to land. (Thompson’s have historically tight barrels, in the .499 - .501 range). Savage 10ML-II barrels are more consistent, usually .501 to .5015 in. land to land. Knight barrels seem to be .502, give or take. Your individual rifle may be anywhere from .499 to .505 or more and still be a “fifty caliber.”
Using low-residue powders promotes accuracy. Blackhorn 209 is the best of breed right now, needing no cleaning or swabbing from shot to shot. Savage 10ML-II users can use Blackhorn 209 with great success and also have the option of cleaner burning, Savage recommended, smokeless propellants. Most of us are sharp enough to use only propellants allowed by the respective rifle manufacturers. Those that read my articles certainly are (wink).
Consistency extends to loading. You certainly do not want to deform your sabot on its trip down the muzzle. Nor do you want to inadvertently cock or cant it. A canted, jogged bullet finds its own center of form upon firing, which explains some “unexplained flyers” that aren’t all that unexplainable after all. The best tool for loading is the “Spinjag,” which fits the noses of most muzzleloading bullets and allows the saboted bullet to naturally engrave and rotate along with the rifling with no induced canting or cocking.
The “Spinjag loader” offers an even greater degree of precision. The Spinjag bullet starter allows a proper start, almost forcing perfect alignment that is then finished off with the Spinjag loader. Nicked, flattened bullets may cause accuracy problems and bullets eccentric to the bore may do the same. Stabbing and poking a bullet down our barrels is an inconsistent way to engrave a sabot and seat a bullet. To the extent that we can give an accurate, concentric, repeatable loading procedure to our sabot our accuracy improves in concert.
The reasons for seeking accuracy are clear: when the only shot that really matters is the next one, we have to strive to take as many accuracy-robbing variables out of the equation as possible. There are enough variables in the field as it is, from temperature, humidity and wind to a variety of ways of steadying our rifles in the field. We can readily adapt and adjust to known variables, the repeatable effects of gravity and wind. We can’t compensate for the unknown variables, though, but by taking the time to remove inconsistencies from our shooting system that are known and under our control long before we head to the hunting fields assures us of the predictably great results we all seek.
Consistency and uniformity may not be the most exciting, romantic, or bombastic terms. Blazingly good accuracy and total confidence when the trigger is pulled are what memories are made from. We can make sure that our moments are worth remembering if we pick the right system and do our homework. It is all the difference in the world, the difference between hunting for our trophies before we pull the trigger, not after.
Copyright 2008 by Randy Wakeman. All rights reserved.