Greatest fear I have is with primers and primer sensitivity.
I have had out of battery slamfires in Garands with Federal Primers . That particular lot of federal primers was too sensitive for the ignition system of a Garand. I have met other shooters who had out of battery slamfires with Federal primers in their Garands, one who also blew the back of the receiver heel off.
All mechanisms with free floating firing pins are susceptible to slamfires. All of them because the firing pin rebounds off the primer at some point in the feed cycle. Garands, M1a’s, M1 carbines, Mini 14’s all have the same basic mechanism but, by design, this mechanism is susceptible to both inbattery and out of battery slamfires because the firing pin is never really totally restrained. At best it is retracted during cam down, but the retraction is not positive because the receiver bridge was primarily designed to retract the firing pin during extraction, nor is the firing pin fully retracted, there is always some bit of firing pin sticking out of the bolt face. These mechanisms require a less sensitive primer because the impact energy of a free floating firing pin will ignite a sensitive primer.
The problem is, you can buy primers that are advertized as less sensitive, the “mil spec” primers, but you cannot visually tell if the primers meet spec. Primers vary in sensitivity based on a number of factors: cup hardness, primer composition, and I found reading DTIC reports, that the amount of primer compound in the cup changes primer sensitivity. Less compound results in a less sensitive primer, which was counterintuitive .
The primary issue I have is Quality Control at the manufacturer. There is no overarching regulatory body in ammunition manufacture. SAAMI is a voluntary industry organization and all it does is publish specs, (specifications that ensure that no one’s product fails!) and the adherence is voluntary . Without an independent body with enforcement authority there is no reason to assume that ammunition manufacturers are going to be honest. Everyone knows that Corporations are in it for the profit and only for the profit. As we have seen, Corporations are amoral in the pursuit of profit, if they make profit and someone dies, or the world crashes, too bad for the person or the world. There is no reason to assume that they don’t ship primer lots that fail sensitivity tests, that is, are too sensitive, because no one out there has primer impact testing equipment, and if your gun destructively slamfires with your reloads, you can’t prove that the primer was at fault. It is a win, win for the corporation because they don’t lose profit rejecting nonconforming product and won’t be sued.
Given all the reports people post of dud primers, it really makes me wonder, how many lots of primers are actually too sensitive? Folks with bolt rifles and revolvers are not going to notice because a too sensitive primer will go bang just like any regular primer, it is only when you stuff these things in semi autos will anything funny happen, and then, how do you know it was the primer?
