Primer Primer

Outdoor Life - - CONTENTS - BY JOHN B. SNOW

Like bul­lets, pow­ders, and brass, primers are un­der­go­ing rev­o­lu­tion­ary changes. We ex­plain the tech­nol­ogy be­hind the least un­der­stood piece of the car­tridge puzzle—and why it will make ammo even bet­ter.

THE SELF-CON­TAINED METAL­LIC CAR­TRIDGE IS ONE THE MOST SIG­NIF­I­CANT IN­NO­VA­TIONS IN THE HIS­TORY OF FIREARMS.

It con­sists of four items—brass, bul­let, pow­der, and primer. Any re­cent grad­u­ate of a hunter-ed pro­gram should be able to rat­tle off this in­for­ma­tion be­cause il­lus­tra­tions show­ing the com­po­nent pieces of car­tridges have been a part of the cur­ricu­lum for decades. What our bright-eyed new hunter might not know is that all four have a pro­found ef­fect on car­tridge per­for­mance, whether we’re talk­ing about ac­cu­racy, re­li­a­bil­ity, or lethal­ity. And not to pick on the poor kid, but he or she prob­a­bly doesn’t have the slight­est clue as to what a primer ac­tu­ally does. In this, our young hunter isn’t alone. Of the four build­ing blocks of a car­tridge, the primer is the least un­der­stood by a long shot. On top of this, a ma­jor ad­vance in primer tech­nol­ogy prom­ises to make to­day’s good ammo even bet­ter. Even the nerdi­est reload­ers—who can make a layper­son’s eyes glaze over as they ex­pound ad nau­seum about the in­tri­ca­cies of the con­struc­tion of a fa­vorite bul­let or their reg­i­men for pre­par­ing brass to ex­act­ing stan­dards—typ­i­cally know lit­tle about the primers they fash­ion their am­mu­ni­tion with, other than that chang­ing from one type to an­other might al­ter the sizes of their groups. Asked to ex­plain what a primer does, shoot­ers often de­scribe it as akin to a match that lights the pow­der at the tail end of the car­tridge, ini­ti­at­ing the process that sends the bul­let along its merry way, or to the spark of a spark plug in the cylin­der of a mo­tor that ig­nites the com­pressed mix­ture of fuel and air. Nei­ther anal­ogy is cor­rect. The func­tion of the primer is more com­plex than ei­ther a match light­ing a fuse or a spark plug fir­ing. To un­der­stand what primers do, we have to delve into the chem­istry that goes into the mak­ing of the vo­latile slurry that is pressed be­tween the primer’s cup and anvil. That mix­ture, known as primer com­pound, is the most danger­ous sub­stance in the world of firearms and am­mu­ni­tion man­u­fac­tur­ing. Though gun­pow­der is flammable, and the chem­i­cals used to blue steel bar­rels are noth­ing you’d want to gar­gle with, mis­han­dled primer com­pound will leave noth­ing but a smok­ing crater be­hind. There’s a rea­son that each in­di­vid­ual primer gets its own pro­tec­tive cutout in the box it is shipped in. The spe­cific in­gre­di­ents in primer com­pounds vary from one make to an­other. But the gen­eral for­mu­las have re­mained re­mark­ably sta­ble over the

decades, mostly be­cause ammo mak­ers—and, more to the point, their cus­tomers—are stub­bornly re­luc­tant to tin­ker with any recipe that de­vi­ates from the tried and true. Above all, primers need to be con­sis­tent. If they don’t pop off when they’re hit by a fir­ing pin—no mat­ter how cold the tem­per­a­ture or how dirty and greasy the ig­ni­tion sys­tem—shoot­ers be­come ex­cep­tion­ally cranky and un­for­giv­ing. Ig­nit­ing the pow­der charge, even at the cost of other de­sir­able out­comes like ac­cu­racy, is the primer’s prime di­rec­tive. De­spite this con­ser­va­tive bent, primer tech­nol­ogy is ex­pe­ri­enc­ing a rev­o­lu­tion right now. While there’s been plenty of hoopla re­cently about the new­est high-per­for­mance bul­lets, pow­ders, and pre­ci­sion brass, the fourth mem­ber of the car­tridge quar­tet has un­der­gone some in­ter­est­ing de­vel­op­ments too. The lat­est gen­er­a­tion of primers has been cooked up by the engi­neers at Fed­eral Am­mu­ni­tion. The new primer is called Cat­a­lyst, and it rep­re­sents an im­prove­ment over tra­di­tional primer com­pounds in sev­eral ways. Be­fore get­ting to the mer­its of Cat­a­lyst primers, how­ever, we still need to an­swer the ques­tion posed above. What ex­actly do primers do?

The Primer Event

One use­ful way to think about a primer is as a mini vol­cano or rocket en­gine that spews a potent mix of hot, burn­ing slag that min­gles with the gun­pow­der con­tained within a car­tridge. Since the 1920s, this mix has been for­mu­lated by com­bin­ing lead sty­ph­nate, the main ex­plo­sive, with an ox­i­dizer, bar­ium ni­trate (which adds oxy­gen to the flame). These two el­e­ments ac­count for about 80 per­cent of the primer com­pound. Added to this are some fuels (16 per­cent) and a dash of tetrazene (4 per­cent), which is a sen­si­tizer—mean­ing it helps the com­pound ig­nite when the fir­ing pin strikes the primer cup. Dur­ing this brief erup­tion, which lasts be­tween 200 and 1,500 mi­crosec­onds (one mi­crosec­ond is a mil­lionth of a sec­ond), three things hap­pen: The primer com­pound gen­er­ates flame and hot par­tic­u­late mat­ter in the form of slag and burn­ing metal, and it cre­ates a gaseous pres­sure front. In a per­fect world, the primer would ig­nite ev­ery grain of pow­der si­mul­ta­ne­ously to give our am­mu­ni­tion the great­est pos­si­ble con­sis­tency from shot to shot. Also, it wouldn’t cre­ate more pres­sure than nec­es­sary, so as not to overly com­press the pow­der in the case, po­ten­tially lead­ing to less uni­form ig­ni­tion. Our world is far from per­fect, sad to say, and in or­der to ful­fill the prime di­rec­tive of primers—mak­ing sure the car­tridge fires—we err on the side of us­ing more primer than nec­es­sary, mean­ing more pres­sure than nec­es­sary. Ide­ally, when the primer erupts, the flame and hot met­als pen­e­trate deeply into the col­umn of gun­pow­der to help get us as close as pos­si­ble to achiev­ing the chimeric goal of ig­nit­ing each ker­nel of pow­der si­mul­ta­ne­ously. If the slag is able to spread through the pow­der, it can trans­fer its heat to the pro­pel­lant more ef­fec­tively. While some shoot­ers like to use com­pressed pow­der charges in their reloads—the idea be­ing that with no air space for the pow­der to slop around in, they will get more con­sis­tent results—this can make the primer’s job more dif­fi­cult, since the pres­sure wave com­ing off the primer can com­pact the pow­der col­umn even more, mak­ing it hard for the slag and flame to pen­e­trate.

A New Cat­a­lyst

Like many in­no­va­tions in am­mu­ni­tion, the de­vel­op­ment of the Cat­a­lyst primer was driven by a re­quest from a large cus­tomer. In this case, the U.S. govern­ment, both mil­i­tary and law en­force­ment, wanted a duty-wor­thy primer that didn’t con­tain lead or other po­ten­tially toxic met­als. Fed­eral turned the project over to one of its engi­neers, Joel Sand­strom, who went on to in­vent Cat­a­lyst. There have been other lead-free primers on the mar­ket for decades, but they weren’t viewed as re­li­able enough for duty am­mu­ni­tion and have been

rel­e­gated to use in train­ing ammo. While elim­i­nat­ing lead was a pri­mary re­quire­ment of the project, Fed­eral ended up cre­at­ing a primer that wasn’t just the equiv­a­lent of the cur­rent lead sty­ph­nate mix­tures, but one the com­pany says is sig­nif­i­cantly su­pe­rior to the older tech­nol­ogy. “It is safer to man­u­fac­ture, and it’s af­ford­able and re­li­able,” says Drew Goodlin, se­nior di­rec­tor of tech­nol­ogy at Vista Out­door, the com­pany that owns Fed­eral Am­mu­ni­tion. One way in which Cat­a­lyst im­proves on cur­rent primer tech­nol­ogy is that it is more com­pat­i­ble with mod­ern pro­pel­lants, mean­ing that it won’t de­grade the pow­der it comes in con­tact with the way some cur­rent primers can. Even bet­ter, the Cat­a­lyst for­mula pro­pels more hot, heavy met­als, while pro­duc­ing less pres­sure from gases, into the pro­pel­lent bed than any other primer sys­tem Fed­eral has used—even its vaunted Gold Metal primers. Though tin­ker­ing with ex­ist­ing lines of am­mu­ni­tion that have a long-stand­ing rep­u­ta­tion for qual­ity and re­li­a­bil­ity is gen­er­ally a no-no—par­tic­u­larly when it comes to primers, which fall un­der the “if it ain’t broke, don’t you dare mess with it” cat­e­gory— Fed­eral is plan­ning on switch­ing all of its cen­ter­fire am­mu­ni­tion—ri­fle, pis­tol, and shot­gun—to Cat­a­lyst primers over the next five years. This, more than any­thing, demon­strates the con­fi­dence that Fed­eral has in the prod­uct. But will con­sumers be as will­ing to em­brace Cat­a­lyst? The fact that var­i­ous el­e­ments of the U.S. govern­ment are us­ing ammo with Cat­a­lyst lends the new primer tremen­dous cred­i­bil­ity. Like all primers, Cat­a­lyst re­lies on three main things to work: a fuel source, an ox­i­dizer, and sen­si­tiz­ers. But the chem­i­cal re­ac­tions within Cat­a­lyst primers are markedly dif­fer­ent from those with lead sty­ph­nate. The most in­ter­est­ing piece of the Cat­a­lyst pie is the alu­minum it con­tains. This ac­counts for only about 10 per­cent of the mix, but it per­forms two dif­fer­ent, yet com­ple­men­tary, func­tions. When alu­minum in­ter­acts with any ex­plo­sive, it makes the ex­plo­sive more sen­si­tive. With Cat­a­lyst, that would be ni­tro­cel­lu­lose, which makes up about 20 per­cent of the primer com­pound. The alu­minum also re­acts with bis­muth ox­ide (60 per­cent of the primer)—yep, that’s the same bis­muth in non­toxic shot with a den­sity sim­i­lar to lead— to cre­ate what Fed­eral en­gi­neer Sand­strom calls a “ther­mite re­ac­tion,” which is a fancy way of say­ing that the alu­minum gets the bis­muth re­ally, re­ally hot. Be­cause it is both very hot and very heavy, the bis­muth does a su­pe­rior job of pen­e­trat­ing the pro­pel­lant bed and trans­fer­ring heat to ig­nite the pow­der. The fi­nal 10 per­cent of the Cat­a­lyst for­mula is a blend of sen­si­tiz­ers, fuels, and binders. By tweak­ing this new base­line for­mula, Fed­eral is able to tai­lor the primer to work in dif­fer­ent types of am­mu­ni­tion, rang­ing from small pis­tol cal­ibers like the .380, which use min­i­mal amounts of primer com­pound, to magnum ri­fle car­tridges and shot­shells, which re­quire much heav­ier pay­loads of primer ma­te­rial to ig­nite their pow­der. The suc­cess of Fed­eral’s bet on this new tech­nol­ogy hinges on pretty sim­ple cri­te­ria: Any­time a shooter loads their gun with Fed­eral am­mu­ni­tion, it needs to go bang, and it needs to place the pro­jec­tile where the shooter is aim­ing. If Cat­a­lyst can do that, then we can safely say we’ve en­tered the next ma­jor phase of am­mu­ni­tion tech­nol­ogy. And even if our new hunter-ed grad­u­ate doesn’t un­der­stand all the ins and outs of primers, there’s a good chance they’ll be par­tic­i­pat­ing in the new primer rev­o­lu­tion when they tag their first deer.

The new Cat­a­lyst primers come for­mu­lated for ri­fle, shot­gun, and hand­gun loads.

The new­est de­vel­op­ments for the most mys­te­ri­ous piece of the car­tridge recipe

Cup

Ig­niter Com­pound

Anvil

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