Where The Bang Starts

A Primer On Primers.

Primers are mysterious things which I fear we handloaders take for granted. Having virtually no intuitive ability or formal education concerning chemistry I’ve never comprehended how they work. A chunk of flint striking a piece of steel and giving off sparks I can understand but a streak of flame coming out of a metal cup holding what appears to be dried putty but only after a firing pin strike is beyond me. Yet for the handloader nothing can replace these remarkable little widgets called primers.

The very first metallic cartridges were rimfire, meaning their priming compound was held inside the case rim. That’s just as .22 rimfires are still primed. Such a system works well for small cases but proved unreliable in bigger calibers. The US Government did try it in their first .58 Government rounds circa 1865 but shortly dropped it in favor of centerfire priming in the .50 Government (.50-70). Winchester’s .44 Henry Rimfire did last several decades but an interesting fact is the Henry and Winchester rifles chambered for that round gave twin firing pin strikes as insurance against misfires.

Early government centerfire priming isn’t the same as what we have today. Primers were inside cases and held by stab-crimps. Except for those crimps the cases on the outside looked like rimfire cartridges. Firing pins actually punched deep in the base of the case to reach the primer. The government stuck with this process into the .45-70 era, only switching to outside primers about 1881. Incidentally, these inside primed cases were made of copper not brass.

Outside primers and brass cases meant reloadability. America’s first reloadable handgun cartridge came along in 1870. It was Smith & Wesson’s .44 American. My research has not been able to pin down exactly when American reloadable rifle cartridges appeared. My best guess would be Remington’s .44-77 in 1867 but don’t make any bets on it. For sure Winchester’s first reloadable, centerfire rifle cartridge was the .44 WCF (.44-40) introduced late in 1873.

In the 1870s there were two basic styles of primers in use. They are known today as Boxer and Berdan. Boxer primers are what we still use. They consist of three items: cup, priming compound and anvil. Upon firing, priming compound is mashed between firing pin and anvil in turn causing that mysterious flame to spurt out through a hole centered in the case’s primer pocket.

Berdan primers consist of cup and priming compound. Cartridge cases meant for Berdan primers have anvils as part of primer pockets. Because the anvils are centered in primer pockets Berdan cases have two or even three flash holes for the flame to travel through.

Obviously it was easier for cartridge reloaders to punch a spent primer out of a case having a large centered flash hole than a case having two or three small flash holes. Hence Boxer priming eventually became America’s standard. To the best of my knowledge Winchester’s cartridges always used Boxer primers. Conversely all ammunition factory loaded by the Sharps Rifle Company of the 1870s used Berdan primers. They must be pried out of primer pockets which is a slow and tedious operation.

From the beginning of the reloadable metallic cartridge era primers have been made in a bewildering array of sizes and types. In my cartridge collection are ancient .38 WCF (.38-40) and .44 WCF rounds with small primers. In my many tubs of old cartridges are a few relatively modern .357 Magnum factory loads with large primers. When cartridge propellants transitioned from black powders to smokeless types another variable was added because also in my collection is an unopened case of 1,000 Remington No. 2 primers labeled “for black powder.”

Thankfully today the firearms industry has standardized on primers. For metallic cartridges there are four basic types of primers: small pistol, small rifle, large pistol, and large rifle. But get this: large pistol and large rifle primers very slightly dimensionally. Their diameters are standard at 0.210 inch but rifle primers are slightly longer than pistol primers. On the other hand small rifle and small pistol primers are dimensionally identical, which in no way means they should be considered interchangeable.

Collectively speaking of all four types of primers we have standard- and magnum-strength ones, and standard and benchrest or match-grade primers. Magnum primers are often a source of confusion to neophytes because being labeled magnum does not necessarily indicate they should be used in magnum cartridges. Magnum strength primers produce stronger and longer lasting flames to help get some types of powders better ignited. Are they ever absolutely necessary? That’s a definite maybe. For instance the 8th Edition Hornady Handbook Of Cartridge Reloading in their section on 6.5x52mm Carcano says use only Winchester Large Rifle Magnum primers with their 160-grain, 0.267-inch bullets.

What kind of shelf life do primers have? That’s another question without a definite answer. I’ve been shooting some German military factory loads for 8x56mmR Hungarian dated 1939 and some 8x57mm rounds dated 1940. They all gave perfect ignition. Along with those I’ve fired British .303 and French 7.5x54mm military ammo both dated 1961. All the British rounds do this: the trigger is pulled, there is a click, a definite pause, and then the rifle goes boom. About one third of the French rounds do likewise. Some very clean French 7.65mm Long pistol rounds dated 1953 were all complete duds.

In this time of primer shortages some panicked buyers are picking up any sort available. If such is you be careful. Use them correctly. Primers are amazingly powerful for their size. If in doubt consult a reloading manual and don’t just take some Internet warrior’s word for what is safe.
By Mike “Duke” Venturino
Photos By Yvonne Venturino

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