Rifle Load Development: How To Find The Best Powder & Load For Accuracy

How do you discover the optimum rifle powder and cargo? Rifle load growth can typically be a trial-and-error effort the place it’s important to put plenty of rounds by means of your barrel to study what it likes greatest. The issue is that we’re attempting to detect comparatively minor efficiency variations between hundreds (e.g., one load has a 0.35 MOA group, and one other may be 0.45 MOA). Whenever you’re attempting to distinguish between these minor variations, you want a big pattern dimension to know with any confidence that what you’re seeing isn’t merely random noise within the information. (Learn my Statistics for Shooters Who Aren’t Math Nerds articles for extra particulars.)

Which means if we’re going to strive a few various kinds of reloading powders and cost weights, then we’ll rapidly find yourself placing a whole bunch of rounds on our barrel earlier than we discover the optimum load. For a barrel just like the 6mm Creedmoor that will solely have 900-1200 rounds of correct barrel life, utilizing up a good portion of that to discover a load is certain onerous in your pockets! 😉

This information will present you how one can streamline your reloading course of and choose the perfect rifle powder to your cartridge.

My Outdated Shortcut: Strive What The Professionals Use

The one shortcut I knew of was to strive what a few of these guys have been utilizing, and possibly that might get me on a really correct load rapidly. I revealed very detailed load information from top-ranked long-range shooters within the PRS, and it’s typically the place I personally go to get an thought of what hundreds to strive:

A Skilled Ballistician’s Method To Load Improvement

Then, just a few weeks in the past, I got here throughout the e-book Ammunition, Demystified by Jeff Siewert (view e-book on Amazon | learn my evaluate of the e-book) – and I’ve realized a ton about ammo! It’s actually the most effective books I’ve ever come throughout associated to precision rifles and long-range taking pictures. It’s written by a ballistic engineer who lately retired after a 40-year profession of analysis and growth regarding ammo and firearms, and the e-book is his method of pulling again the curtain on the “black magic” of ammunition and sharing the info and insights he realized by means of many years of analysis and being an business insider.

Jayden Quinlan, senior ballistician at Hornady, says that he finds himself pulling this e-book off his shelf weekly to reference one thing. It’s fascinating, and I don’t suppose something prefer it has ever been revealed.

Right here is the intro to one of many sections within the e-book:

“I’ve learn a lot of articles in numerous publications in regards to the impact propellant has on the dispersion of a given load, most of it well-intentioned, however almost all is sorely missing in clarification as to the actual parameters resulting in a selected propellant being accountable for taking pictures a small group dimension.” – Jeff Siewart in Ammunition, Demystified

Jeff systematically outlines all the particular components that trigger powders to fireplace small teams or not. Jeff not solely agrees that the powder you employ can affect your dispersion however explains all the intricacies of how powder can change a bullet’s flight.

I gained’t spoil all of it, however I did wish to share just a few sensible ideas that Jeff covers in his e-book.

There are three main methods adjustments in propellant can adversely have an effect on dispersion, even in the event you put exactly the identical weight of propellant in the identical case.

If the propellant is just too sluggish for the applying at hand, the case could also be filed with powder, however the propellant possible gained’t fully burn out previous to the projectile exiting the barrel. The unburned propellant grains topic the bottom of the projectile to a hail of small, externally utilized hundreds, oriented randomly (across the circumference of the projectile as considered from the bottom), that may push the projectile round. Whereas the masses imparted by the unburned propellant grains impacting the projectile could also be small, spin-stabilized projectiles are particularly delicate to externally utilized hundreds at their aft finish. One other risk with a propellant that’s too sluggish for the meant utility is that it often ends in larger than desired strain on the projectile base on the muzzle exit. Excessive however variable base strain at muzzle exit, mixed with a mechanical asymmetry on the muzzle (imperfect muzzle crown), can impart variable unbalanced hundreds to the projectile base, disturbing the projectile flight. …

If the propellant is just too quick for the applying at hand, the case is not going to be fully stuffed with propellant (if we’re taking note of strain limits). With the case lower than 100% full, there’ll regularly be a shot-to-shot variation within the distribution of the propellant within the case because the primer is initiated. Variation in propellant distribution at ignition results in variations in flame unfold by means of the propellant mattress, resulting in bigger than desired variations of peak strain, time to peak strain, muzzle velocity, and in-bore journey time shot-to-shot. … Since there are not any straight barrels, variations in peak strain, muzzle velocity, and motion time result in adjustments in barrel pointing vector because the bullet exits the barrel, rising dispersion. On this explicit occasion, an inert filling, akin to powdered child cereal, over the propellant mattress aft of the projectile can forestall propellant from wandering round within the case throughout dealing with and chambering and doubtlessly scale back shot-to-shot variations dangerous to good dispersion.”

… and also you’ll must learn the e-book to see the third issue. It’s on web page 132.

Rifle Load Development for Long Range Shooting

Within the e-book, Jeff factors out a number of nuanced tradeoffs between totally different powder traits. By understanding the science and physics of what’s truly taking place, we will make higher selections by way of what “putting the suitable stability” may appear to be for our rifle and utility.

Each cartridge has a wide range of applicable powders from which we will select, that are listed as choices in reloading manuals. Which powder ought to we strive first? An expert ballistician typically has a way as to which powders are probably to provide the smallest teams.

As a result of Jeff was an business insider for 40 years, he shares beneficial perception by way of observations that a number of small-caliber ammunition producers have made by way of what kinds of powders appear to be related to smaller teams. It’s at all times attention-grabbing if you see a number of impartial groups come to comparable conclusions.

“One attention-grabbing remark that has been made by a number of small caliber ammunition suppliers is that, all else being equal (e.g., for given case/bullet mixture and given muzzle velocity), smaller teams are related to propellants having larger relative quickness. Because of this the bullet attains a given peak strain earlier in its in-bore journey and considerably has diminished base strain because the bullet exits the barrel. Any tilt of the bullet in-bore with respect to the bore centerline will generate a circulate asymmetry at muzzle exit, inducing an angular price on the projectile. Use of powder with elevated relative quickness can be anticipated to see a discount in each base strain at muzzle exit and the frequency of unburned propellant grains exiting the barrel. Each these ought to assist scale back group dimension.”

After we’re doing rifle load growth looking for the smallest teams and greatest precision, Jeff says what we’re actually doing is in search of a powder that burns out fully whereas filling the case as near 100% loading density as doable with out exceeding the allowable strain.

Right here is how he summarizes knowledgeable ballistician’s strategy to load growth by way of what attributes they’re going to search for in a reloading powder:

As partially acknowledged above, the perfect propellant for a selected utility possesses these attributes:

The case is stuffed to higher than 95%-97% of the utmost bulk loaded density to maximise muzzle velocity.

Peak most working strain of the weapon isn’t exceeded on a frequent foundation.

The propellant grains are fully consumed previous to the projectile exit from the muzzle.

The propellant is straightforward to ignite when conditioned at chilly temperatures with out changing into brittle. Propellants containing nitroglycerine (e.g., double-base or triple-base chemistries) have a popularity for sensitivity to cold-temperature circumstances as a result of crystalline transition temperature of nitroglycerine being simply 15-20° C above the standard -40° C usually specified for operation of army propellants. Under this temperature, the grain can fracture in uncontrolled methods, inflicting a fast enhance within the burning space of the propellant and a ensuing spike in peak strain.

The propellant has a low temperature coefficient; its efficiency isn’t overly delicate to will increase or decreases in ambient temperature.”

If you happen to’re nonetheless studying this text, then I assure you’ll love Jeff’s e-book. There are a ton extra nuggets of knowledge in there that I’d like to share, however you need to simply go purchase it!

Coming Up Subsequent

My subsequent article will dive deeper into Jeff’s final bullet level above, which is rifle powder temperature sensitivity. I’ll share perception from one other group {of professional} ballisticians who actually produce over 100 million rounds of ammo yearly. I’ll additionally quantify what meaning to the long-range shooter in sensible phrases. Keep tuned!

This text is a part of a sequence on rifle reloading information, load growth, and reloading elements. Listed here are different associated articles that I’ve lately revealed or plan to publish within the close to future:

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