Well, back in SOT, the chief pistol instructor, the late Paul Poole, used to tell us “Never dry fire in a firefight!” In those days, CT work (only the British called it CQB then) was done with pistols, although we were experimenting with both the newfangled H&K MP5 and Colt’s oldfangled XM177s, a few of which were around but very beaten-up; Colt had a new version with a 14.5″ barrel that they said solved all the 177′s problems, except for the big fireball and ear-shredding report.
We’d have gone to Hell to bring back the three heads of Cerberus for Poole, a Son Tay raider and Bob Howard’s recon-running-teammate, but it wasn’t just for his history: the guy was a dead shot, making steel E silhouettes ring with a .45 at 100 yards, and entertaining as hell, with a foghorn laugh: “Bwah-hah-hah! Never dry fire in a firefight!” when one of us was caught with his figurative pants down and his literal 1911A1 slide locked back. And his instruction was pure common sense and experience, and we all got better — a lot better — under his tutelage.
Even if he did assess our personal pistol skills and make a little presentation in front of the guys: an M79. “Hognose, you need an area fire weapon. Bwah-hah-hah!” Ouch.
Later we found out that it was simply that somebody had to be the team grenadiers, and two of us were pulled for the honor. Poole just couldn’t resist making fun of us. (On the plus side, you get creepily good on a 79 with a couple 72-round crates a day to burn. Even if it does chew up the web of your hand).
But we did start counting rounds, at least, per mag. With the 1911, of course, it was easy. It would go bang exactly 7 times from start, and if you forgot in the stress of action how many bangs you had left, you dropped the old mag in your leg pocket (if you had time) and started counting from 7 again. What we didn’t do, though, is count rounds total. Only the snipers did that, and that was because their M14-based M21 sniper systems were a bit of a hothouse flower, sacrificing some of the M14′s robust Garand-based strength for excellent accuracy.
The snipers! Those guys were firing over our heads and next to us as we went in on training targets… one we recall with clarity was a set of wooden stairs with a door at the top and windows to its sides. In the door were two concrete cinderblocks and in each window was another. The snipers had to (and did) pop the blocks in the door as we assaulters charged up the stairs, popping the blocks in the windows with our .45s. The life of the M21 barrels was not long (the snipers did not clean them vigorously, to prevent muzzle wear; the M14 design doesn’t allow cleaning from the breach).
None of the 1911A1s had been built, as far as we knew, after 1945, and God alone knew how many rounds they’d seen. The 1911 would keep firing until a Magnafluxing at one of the periodic rebuilds showed cracks, usually in the slide. The round counts on the 1960s-vintage M16s and XM177E2s were also a mystery. Or even the newer CAR-15 carbines or MP5s… they got shot a lot.
But the idea the snipers had, to count the rounds so you knew when the rifle was about ready to go back to depot, was a good one. They actually logged them in a book (and this continued when the more-accurate and -durable M24 replaced the somewhat improvised M21 with its Leatherwood Automatic Ranging Telescope). The trouble is, of course, that logging rounds is a great deal of work. But if the whole Army could do it, we’d get a lot more information about how long small arms and their components are good for, and we could begin to schedule inspections and overhauls more intelligently. Too many inspections waste money, and some percentage of overhauls go and rebuild guns that don’t need it, while some other percentage of guns that need overhaul, based on their condition, don’t get picked up. (Army ordnance experts think that both of these numbers, the false positives and the false negatives, are about 40%)
For over 10 years the US Department of Defense’s Joint Services Small Arms Program and its constituent service ordnance departments have been trying, with limited success, to develop an automatic round counter for combat firearms. SOF elements have moved ahead of the JSSAP on this, thanks less to general SOF awesomeness, and more to SOF budgets, and they’re futzing around with fielding round counters now.
While the civilian market has round counters, they remain fiddly and unreliable, and many of them are focused on counting down the rounds in your magazine. The military frets less about that, and more about the problem of wear and tear on high cycle small arms. What they’re looking for is something that will give them a shortcut to understanding the condition of a firearm. They see this working in the way that an odometer lets you judge the point a car is at, in its factory-to-scrapyard lifecycle.
There are several ways that systems subject to wear and tear can be singled out for overhaul or rebuild:
- They can be selected due to calendar years of age since production or last overhaul. This is what historically has been done with most Army small arms.
- They can be selected “on condition.” This means that they are subject to frequent inspections, and weapons that failing inspection criterion or criteria are selected for overhaul. This is the other mechanism that sends Army small arms to the depot for rebuild.
- Or, lastly, they can be selected based on usage metrics. This is not done currently, because apart from sniper weapons, and for that matter, sniper weapons used by SOF mostly, few weapons have their usage recorded accurately and reliably.
Each of these approaches has problems. Calendar year replacement means that most parts you are replacing will probably still have many years of service in them. Likewise, many of the problems that degrade small arms accuracy and reliability can’t adequately be documented in an armorer’s condition inspection. Finally, usage metrics also are imperfect: evidence teaches us that not only the amount but also the intensity of use has an effect on weapons wear.
Why Counting Rounds Works for Weapon Maintenance
Let’s consider some real-world examples. The things that kill Stoner system rifles are barrel wear (which degrades first accuracy, then reliability) and metal fatigue in the locking mechanism, especially in the bolt (which is primarily a reliability threat.
The two real problem areas in rifle barrel wear are throat erosion and gas port erosion, both of which degrade accuracy and reliability. But the means the Army currently uses to detect throat erosion, the same taper gauge used to detect muzzle erosion, doesn’t work reliably at the back end of the barrel. It misses a high percentage of badly eroded chambers (well, actually, throats), “false negatives,” while identifying a rather high percentage of “false positive” chambers, that are still perfectly accurate. And outside of the depot, where the port can be examined with a borescope, there’s no way to judge gas port erosion at all.
Fatigue undermines the bolt all over, but the bolts fail in two areas: the locking lugs, and at the hole for the pivot pin. Both are places where the metal is limited but stresses concentrate.
A locking lug failure (like the single-locking-lug failure common on the Beretta) may not immediately fail the weapon. That depends on where the broken chunks of lug go; but most places they might go will interfere with something. Moreover, as each lug fails, the remaining ones bear more burden, and they usually fail in an accelerating sequence as the burden of seven lugs is borne by six, five, four… the gun generally jams before you get to zero.
The next most common place for bolt failure is at the thinnest section of the bolt, where it’s drilled through to accept the pivot pin. Any asymmetry in forces here, which may result from even microscopic as symmetry of the park part, causes the forces to load up on one side or the other, and over a great deal of time, or if there’s a presence of a Nick or any other stress riser, crack begins to propagate on one side or the other. Even before the first side is completely cracked through, it’s weakened ability to bear loads increases stress on the other side, Waiting to a matching crack over there. The bolt can crack through on one side or on both, and is cracked through on one side, will quickly crack through on the other. A redesign of this area to reduce the diameter of the pivot pin, leaving more cross-sectional material in the bolt, or adding rollers to reduce friction, might increase durability here. It’s hard to judge whether it’s actually necessary, because bolt failures are relatively uncommon, and redesigning the pivot pin mechanism may introduce new failure modes.
The bolt seems to fail, whichever failure mode gets them, before the lugs in the barrel extension let go. Obviously bolt failures are catastrophic failures that take the weapon out of service either instantly or very rapidly (within a few more rounds); there is no fail-safe bolt failure mode. Bolt failures always occur during firing, never during non-firing weapons-handling, and therefore they have a potential to happen during combat, which is by definition a Bad Thing.
The current maintenance schedule sends small arms to the depot for analysis in large batches, commits weapons to overhaul that have years of useful life, or, even worse, sends them after they display failure in the field. Everyone knows that you have to turn in the rifles with the broken bolts illustrated here. What we don’t know is: can you catch the problem before it is catastrophic, or even visible, with round-counting?
So this is the why of round-counting (there are a few other wear modes, like to the gascheck rings, but this is the meat of it). First, we can use round-counters to identify specific weapons that have had higher usage than their rackmates, and that we would expect, ceteris paribus, to be be more needful of maintenance. Once we have an automated round-counting system in place, we can correlate round-counts with wear and failures systematically, and the data-collection potential gets interesting. A first-generation round counter is itself certainly useful, but still a rough device. All rounds are not equal, and that leaves us growth potential for improved future versions. We know from decades of experience, for example, that automatic fire wears guns of all kinds more severely than the same number of rounds fired semiautomatically, and that heavy, sustained automatic fire is very deleterious to accuracy. You may recall this post from last year wherein we noted that WWII armorers observed that .50 ANM2 aerial machine guns that had been fired in long bursts lost their accuracy even though the barrels gaged normally in all dimensions. An M4A1 is not a .50 but there may be analogies in the physics and metallurgy at work in each.
Round counters give us data points we didn’t have before, in other words.
(When we figure out where we stowed it, we’ll link the 2006 SOFIC presentation from which the images and many of the facts have been drawn).