Ammo Reliability

Posted by on February 5, 2012

There is an old saying “the first requirement for a gunfight is to have a gun.”  Some readers might not understand that, but we gun types know that it is just another way of saying “don’t get into it if you are unarmed,” or “your gun is no use locked in a safe at home.”

But I believe there is a more important, and less often mentioned factor, “the first requirement of a gun fight is to have a gun that WORKS.”   I saw a surprising number that didn’t.   Imagine pulling your gun, thus inviting fire, then finding it goes “click” not “bang.”

Handguns don’t work for a variety of reasons, but today I’m going to talk about the reliability of ammo.  It is generally considered a bad idea to carry handloads for defense.  Partly, that’s because of the habit of prosecutors to characterise it in court as your determination to assemble stiff loads to inflict more damage than necessary.  But it is also to avoid the risk of unreliability from poor handloading methods.

I have a 38 Special handloaded cartridge (not loaded by me) with a reversed primer.   But the factories are not perfect, and I well remember a 270 Win factory cartridge with a reversed primer.  That was in the gun shop where I was gunsmith.  That was a very rare item, to be seen once in a lifetime, but my boss couldn’t be persuaded not to return the box to the importer for refund.   In hindsight I was nuts not to have bought the box.  I do have a new WW 308Win case with no flash hole.

I have also seen a box of 30-06 factory ammo, few of which would chamber in the rifle for which they were bought.  I didn’t have a 30-06 headspace gauge so I couldn’t say whether the chamber was overly tight, but the rifle owner said that he had not encountered that problem before, and sure enough, various other factory cartridges chambered and extracted without trouble.

Yesterday I was serving as RO at my local range.  I had a chat with a security guy, who showed me an LM4 on which some idiot has replaced missing screw from the front sight, with a self tapper.   There are two opposing screws for lateral adjustment.  The front sight blade is now loose and thus innacurate.  It prompted discussion about the careless way in which many security personnel treat their weapons, and the importance of reliability of arms and ammo when the chips are down.

It reminded me of some of the faults I’ve seen with ammo.  Perhaps the most common is 9mmP.  Some older dies, including mine, have a crimp shoulder that seems to be more a roll crimp than anything.  But pistol ammo headspaces on the case mouth, which must therefore be a well defined shoulder, or step.  A roll crimp destroys the headspace, and in fact a 9mm cartridge with a roll crimp can jam itself into the chamber throat, and tie up the gun.  I’ve seen that quite often.  The answer is to use four dies.  That is, set the seating die (that’s the third die) so that it seats the bullet to the correct depth but does not crimp.   Then finish the job with a taper crimp die.  

A few years ago I loaded some 40S&W ammo for a friend’s Para Ordnance.  As he had bought a four die set I loaded the first few batches with all four.  Then I noticed that the Lee seating die did a better job than my old RCBS dies, so I figured I didn’t need the fourth (factory crimp) die.  At the next range session about one in four cartridges wouldn’t fully chamber.  They almost chambered but not quite, leaving the slide two millimetres short of closing.  The cartridge was always jammed solid in the chamber and had to be carefully tapped out with a cleaning rod while a second pair of hands gripped the pistol and hauled on the slide.

Investigation revealed that the chamber was slightly tighter than SAAMI minimum, while some of the loaded ammo was max or slightly over.   I forget the exact figures, but as I recall, the chamber was 424, while the ammo varied between 4235 and 4245.  The chamber is slightly tapered, so the ammo was wedging just before the chamber throat.  The Lee factory crimp die reduced the case mouth to slightly below 424.    Not much below, but enough to chamber.  I have not measured any factory ammo, so I can’t say whether it is significantly smaller than 424.  But I wouldn’t want to rely on that pistol in a tight situation.  No matter how well it might work on the range because of the factory crimp die, less than half a thou clearance all round is too close for comfort.

Lyttleton Engineering in South Africa once offered the Vektor CP1, a little polymer framed pistol in 9mmP.  It was a fixed barrel gas operated delayed blowback type, similar to the HK P7.   One day, on the range, my handloads that had worked flawlessly in my SS220 for years, failed to feed in a CP1, in a manner very similar to the Para Ordnance  described above.   So, when Lyttleton engineering had a stand at an exhibition at a Cape Town range, I took some of my handloads along.  Sure enough, the problem repeated itself, and Lyttleton’s engineer diagnosed the problem as slight residual flare at the case mouth that my seating die hadn’t ironed out.  He also admitted that the CP1 chambers were tight.  My SS220 had no trouble because its chamber, like most service pistols, is generous enough to handle less than perfect ammo.

That’s when I bought a Lee factory crimp die.  At a later test, the same CP1 fed that ammo perfectly.

The lesson is clear.   Understand what makes reliable ammo, load it carefully, and if you intend to carry any handloaded ammo on business, shuck it all through the pistol to ensure that it feeds and extracts. 

Vektor CPI  HK P7


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