Quality Control is the topic of the next series of articles I have chosen to tackle, think of this installment as an overview.
What do ammunition, condom, and medical device manufacturers all have in common? They only have one chance to get it right. When they don't, everyone knows about it. This is why ammunition manufacturers should take more than a few lessons from the other two: test, retest, and test again. But when you have only one chance to get it right, how do you identify problems?
Manufacturing is a process, and the more the process is homogenized, the more homogenous the end-product will be. In the case of ammo, the refinement of the process must extend not only to the end-product, but to all of the feed stocks going in.
I talked previously about load development and how important it is to producing quality ammunition, well, when someone changes something it's important you find out about it before your customer does.
The most important aspect of all ammunition is that it does the exact same thing every time. Anyone with a background in statistics, a knowledge of chemistry, physics, or simply a bit of experience will tell you that's nearly impossible so we have to develop a set of tolerances that meet our expectations.
When it comes to ammunition what are the important factors that determine quality? For the average Joe, this usually means, it fits in the right gun, it feeds through the magazine, it does not blow up the gun, is accurate, and goes off every time. But what are the factors that control this? To address them as a list:
Ammunition Fits in the gun making sure ammunition fits in the gun has three critical factors case dimension, bullet geometry/seating depth, and primer seating depth. The easiest way to find out if any of these issues are present is to use a cartridge chamber gauge. These are different from most "case gauges" in that they are typically cut to precise chamber dimensions, usually with a chamber reamer from either a piece of barrel stock, or stock bored to correct dimensions. Any protrusion of the cartridge from the gauge will denote the first two problems, a simple "feel" test will typically identify high primers, and if need be a depth gauge can be used.
Ammunition feeds through magazines the number one issue here is bullet geometry and seating depth. Certain bullets due to their geometry simply will not feed in certain guns. A key example of this is Keith Nose Semi-Wadcutters, they feed very well through 1911 pattern guns, but typically do not feed reliably in newer guns such as Glocks and Springfield XDs. The best way to address this issue is through direct firing tests. Also, seating depth plays an important role here as rounds that are over max-OAL may not fit in the magazine, or may bind as they stack jamming cartridges in the magazine. Maintaining a proper OAL and proper testing are the best ways to identify these problems.
Does not blow up gun avoiding a dangerous situation such as this is mostly a matter of attention to detail when loading cartridges, making sure the correct amount of the right powder goes into the cartridge is the most important way to avoid an explosion that will damage the firearm and possibly the shooter too. Pressure testing ammunition when powder or primer lots change can be a very important step in large manufacturing environments to ensure the load recipe is safe.
Accuracy is a function of consistency, which is where this is best addressed, making sure loading machinery delivers a consistent charge, the bullets are all of a similar weight, similar diameter, and uniform dimensions, and the primers deliver a similar spark are all factors that determine how consistent your ammunition will be from round to round. Occasionally there are bad combinations, that no matter how hard you try, never deliver consistent performance, but that should have been taken care of during the load development stage. Checking lot consistency is best performed with firing tests.
Reliability is making sure rounds go off every time they are prompted to do so, like many other gremlins, this one is best identified by lot-testing. Typically, when a problem like this creeps up it is either due to a dirty machine not dispensing powder the way it should or the primer not performing it's task. In general, these failures are nearly always the result of contamination or manufacturing defects. Primers not properly charged with a styphnate pellet, dried incompletely, or contaminated with oil (this can happen after manufacture as well). Typically charging issues are related to oil or grease contamination in the dispensing mechanism, or can occasionally be related to settling and bridging if the machine is idled for any length of time.
The main point that should be taken away from this: Test, take corrective action, repeat.
The next article will get in-depth on Dimensional Issues (Making sure cartridges fit).
