The concept of armor piercing ammunition is far from new; and probably originated when a bemused archer sat watching his armoured opponent chase him down after just pinging a couple of broadheads off his opponents plate.
Over centuries as weapons grew progressively more powerful so did the armor, but there is a kink in the logic, a weapon carried by its user can employ a multitude of munitions for a variety of purposes and the weight will remain comparable however the armor used to negate the higher end of that projectile penetration range becomes inordinately heavy/mobility sapping to it's user.
Munitions defeat armour via one of two mechanics or a combination of both. Speed of projectile, and/or weight of projectile. The logic is simple, you are either going to send the projectile so fast that by the time it slows down through abrasion resistance of contact with armour it has already negated said armor, or you are going to fire a round whose composition is so dense or projectile weight is so heavy that it punches clean through the armor. Or, as previously stated, a combination of both logics.
The rounds with the highest penetration, that do not appear to fit a sporting purpose, have traditionally been seen as those which should not be available to the public, just in case, you know, someone decides to bang it out with police in a bank parking lot at 9:30 in the morning.
These restrictions and the associated need for officer safety pre-dates North Hollywood by many years. After a couple of months down this particular rabbit hole I wanted to address a single line of communication transmitted during our studied event.
At approximately 0940hrs Sgt Dean Haynes, now covered by a substantial tree on the northwest corner of Laurel & Archwood, and some two and a half minutes after hearing that Phillips had retrieved an addition weapon from the trunk of the Chevrolet sent the following two messages.

Haynes behind 'his' tree, the firefight was far from over at this point.

'L40 be advised that the suspects may have armour piercing ammo' When asked to clarify by the PSR:
'It's possible they have armour piercing ammo'
What caused Sgt Haynes to voice this concern? Unfortunately, bar two interviews on Saturday March 1st 1997 Sgt Haynes has consistently remained unavailable for comment.

North Hollywood Sgt. Larry 'Dean' Haynes

The media devoured his comment, and very soon it became difficult to find a single news report regarding the shootout that did not include the words 'armor piercing ammunition'.
But were they right? Had true AP ammunition been used.
I set out to learn the history, and find out what was used that day.

We shall not go back to medieval times and Bodkin arrowheads etc; instead we shall start in 1967 over two thousand miles away from Los Angeles in Lorain County, Ohio.
The county coroner, Paul Kopsch, together with Daniel Turkus Jr (A City of Lorain police officer) and Donald Ward (Kopsch's investigator) would patent a design in 1967.
A handgun bullet, for law enforcement use, which by design was supposed to effectively penetrate windshields and car doors and neutralize the target within.

The hardened bullet was coated with Teflon in an effort to reduce friction within the barrel from the hardened projectile, it was also said to equalize the angle of penetration, depending on which source you read.
It appeared one of the problems was distribution, as KTW sold their wares not directly to police departments but to gun dealers who could sell the ammunition at gun shows as long as the buyer signed a form stating they were law enforcement.
The problem for KTW came in the form of Mario Biaggi, an ex NYPD Sgt who turned his hand to politics when he retired from the force. Mr Biaggi had multiple issues with KTW's business model, and in front of the House of Representatives subcommittee on crime in March 1982 he got to question Kopsch.
He would cite a private FBI study on the efficacy of KTW against current police worn body armor (which seems to have only really been a thing post 1974). Biaggi testified that the report, which was not at the time and remains to this day unavailable to the public, stated that the green Teflon coated projectiles could penetrate seventy plus layers of Aramid (coincidently made by the same company that made the Teflon, Du Pont), body armor of the era had less than one third of the layers needed to effectively stop such a bullet.

A sample of KTW's infamous ammunition
9mm version of KTW AP Ammo

Biaggi also railed against KTW's distribution methods, with less than subtle implications that the Ohio company were not doing enough to regulate sales from reaching private ownership.
Kopsch, far from an unintelligent man himself, refuted the FBI reports findings and defended his company's ethics.
In a much later interview, 1990, Paul Kopsch stated "We never sold [KTW] to the public. Sales were always limited to the police and the military. It had been available to the police and military for roughly five years before Biaggi started this ... it was a hoax on [Biaggi's] part that got him national publicity.'
Without turning what is already going to be a massively long page into the history of KTW alone, we shall just leave the upshot of those hearings as thus: Later in 1982 Du Pont withdrew all sales of Teflon to not only KTW but all companies involved in the manufacture of ammunition, KTW themselves eventually sold out to a fellow business and eventually faded from view altogether, and many states imposed bans and restrictions on the green colored ammunition.

An extract from H.R2280, H.R5392 & H.R5437. March 20 & May12 1982

It mattered not though, because backed mainly by a report that the public was not privy to the trope of the 'cop-killer ammunition' had been born into public consciousness. So prevalent was it that it would even feature in Hollywood blockbusters such as Lethal Weapon.

Step forward a mere three years and the 'Law Enforcement Officers Protection Act of 1986' was tabled, domestically produced pistol ammunition which could penetrate vests had been allegedly been addressed (despite there being at least five other products widely available that could do the same, including an importation of thirty million Czech handgun rounds completed in the 1970's for commercial sale that fell foul of the 'shouldn't be allowed to penetrate a bullet resistant vest' metric).
The 1986 Act was designed for further restriction of armor piercing ammunition, and to quote the Act directly, 'outlaw the manufacture, import, or sale of armor-piercing ammunition except for government use, including military and police, testing, research, or export.'
The ongoing classification and restriction of such ammunition had originally, and wisely, been limited to handgun ammunition but now those definitions became split. One limited ammunition to composition, the second by jacket weight, size and intention of use.
(B) The term "armor piercing ammunition" means—
(i) a projectile or projectile core which may be used in a handgun and which is constructed entirely (excluding the presence of traces of other substances) from one or a combination of tungsten alloys, steel, iron, brass, bronze, beryllium copper or depleted uranium; or
(ii) a full jacketed projectile larger than .22 caliber designed and intended for use in a handgun and whose jacket has a weight of more than 25 percent of the total weight of the projectile.
Due to the wording of the bill, rifle ammunition would end up exempted, for now.

January 17th 1989 saw a tragedy unfold in the schoolyard of Cleveland Elementary School, Stockton, California. A social deviant who should never have been allowed dominion over a food processor let alone firearms decided that his day should be filled with the sound of gunfire aimed at young children.
The three minute attack left five children dead and thirty two injured. The shooter died at the scene. His weapons of choice were a Norinco Type 56S rifle, and a Taurus pistol.
A truly sickening attack that had zero justification in any mindset bar the deranged.
Fuelled by the atrocity in Stockton, California legislature would pass the Roberti-Roos Assault Weapons control Act of 1989, banning over fifty named firearms.
Norinco models started at number two on that list.
Norinco the state arms manufacturer of China would be losing a huge export market because of this law, so they set to work.
In 1990 they released a new variant, specifically to plug the hole left by the previous year's legislation.
Taking a Type 56 receiver they removed the stock, fitted a thumbhole stock, removed the bayonet lug (never seen a drive by bayoneting myself but ok, whatever) and restamped the receiver as MAK-90, Modified AK of the year 1990, which was a little bit presumptive of the Chinese as these had not started life as original AK rifles, AK pattern yes, but labelled as Type 56 Sporters.
So change the name you have solved the problem right? Well we all know that isn't the case.
As this firearm was not officially named in the extensive list of prohibited weapons, it passed scrutiny. Yet functionally it was identical. In the near future a lot of things would become about how a firearm looked rather than how it operated, but that is a story for another day.
Another ban was in the pipeline, hideously restrictive to millions of law abiding gun owners, but in the meantime two firearms manufacturers decided to throw a massive spanner in the works.

Whilst many brands of foreign 'assault rifles' were now banned from importation, Chinese ammunition could still pass into the country unhindered; and that would also soon become a problem.
Remember the whole KTW saga? How far it went and the implications? Well this is where everything went sideways.
No domestic production of rounds classified as armor piercing that could be chambered in a handgun, that seems to be the gist of it right?
Well what if you take a rifle, shorten the barrel, remove the stock, make the thing as small as possible? Well the ATF class anything with a barrel under sixteen inches as a pistol, kinda. If it retains its stock it can be classified as an SBR, a short barrelled rifle.
No stock and short barrel then in the eyes of the law it's a pistol, and what are pistols not allowed to chamber? Riiight, armor piercing ammunition.
In the early 1990's both B-West, and Olympic Arms each modified a current firearm template, one an AK pattern and one an AR15 pattern to produce both the MARS and the OA-93 respectively, both pistols in the ATF's view. Each model was made in two main calibres, both 7.62x39mm the ubiquitous chambering for the AK platform, and then also in 5.56mm from the AR15 platform.

Olympic Arms OA93 chambered in 7.62x39mm
B-West MARS pistol chambered in 7.62x39mm

The decision to manufacture these firearms allegedly angered the firearms industry and gun owners alike, for the enlightened among them could see what was about to happen.
Samples of these firearms are, whilst not common, certainly available on certain auction sites to this day. However very little data exists on them with some sources stating there was less than one hundred models of each made.
The problem came from the ammunition that could potentially be cycled through them; for you see Chinese ammunition was not built like akin to other countries. (The 5.56mm ammunition would not come under scrutiny until quite recently, the AK chambering got immediate attention)
For the non firearms savvy of the readers out there, the typical thought when someone says bullet would be a shaped hunk of lead that is discharged from the barrel right?
In it's purest and simplest form this is correct, however bullet development has a long and storied history. Copper jackets were added to the outside of the lead to stop high speed lead projectiles breaking up; development of this theme has seen us with many variations that have endured over many years.
Norinco had discovered that by wrapping a soft steel core with only a sliver of lead before the copper jacket was added that they could save a lot of money, as mild steel was cheaper than lead, and the produced bullets retained acceptable flight and penetration characteristics. Cheap production meant a cheap price to the end user, and in the late 1980's/early 1990's cheap Chinese ammunition was needless to say, abundant.
In April 1994 the ATF proposed a ban on all Chinese produced steel core ammunition, millions probably tens of millions of rounds were already present within the country but no more would be coming in.
The ATF, to all logical and interested gun owners had made a faux pas. They had classified Norinco's 'Yellow box' (and white box...oh and green box etc etc) ammunition as armor piercing.
The same year, early 1994, the Federal Assault Weapons ban went into effect for ten years, an absolute mess of logic that doesn't really impact this subject matter but for the uninitiated it basically restricted firearms by their look rather than their functionality. Seems there was a lot of this going around.

It is now we must look at the constitution of what is true armor piercing ammunition and what is ersatz armor piercing.
A true AP projectile is constructed one of two ways, a solid projectile made from a defined list of materials, or an identical projectile contained within a copper jacket.
Illustrated below is a true Russian made 7.62x39mm AP round, cutaway to show it's construction.

Sectioned Russian 7.62x39mm true armor piercing projectile
Norinco 'Yellow Box' 7.62x39mm steel core projectile

You can note the copper jacket, the minimal volume of lead and the hardened steel core. Hardened is the key word in this description.
As a comparison the image beside it shows a Chinese produced round of identical calibre.

Granted the Norinco has been sectioned horizontally rather than the Russian that was done vertically but what can we see that that corroborates the AP classification?
A steel core right? To be expected. However the core itself, without getting to the composition just yet, has subtle differences. Flat nosed as opposed to it's Russian cousin's machined pointed ogive. The core itself is only a mild steel and whilst it has slightly greater penetrative qualities over its lead core/copper jacketed brethren it falls significantly short of a true AP round's penetration.
Steel core, with a faulty ATF classification (as the core is soft steel and not hardened) that could be chambered in an AK variant pistol, was seen as a clear and present danger to law enforcement. Instead of taking the manufacturers of the two firearms to task the supply of cheap readily available ammunition to millions of sporting shooters was cut off in a heartbeat.
All of the above information becomes moot though, a lead cored 7.62x39mm basic round was quite capable of penetrating a police officer's vest. But that is not the issue here, identity of AP is, so let us proceed.

We have discussed some of the history of armor piercing ammunition, of the legislations against civilian ownership, and the makeup of the calibre used in the North Hollywood event itself.
Now it is time to look at what could have prompted Sgt Haynes transmission seventeen minutes into the firefight.

Los Angeles Police Museum has the world renowned display relating to this event, yet all is not all as it appears to be. On my first visit to the display back in 2012 I remember walking into that small room on the third floor, and the first thing that struck me was the masks. The mannequins are sited on an enclosed raised floor and the very real feeling of these two mannequins towering over you is initially a little startling. As the minutes passed and I drank in the details I began to notice some things were very wrong with this display. The first was that Phillips mannequin was not broad enough, appearing too slender (In contrast, Matasareanu's mannequin is quite well proportioned), my eyes drifted downward and I was surprised to see that the Phillips dummy was wearing black cargo pants, not the Levi's 560's he actually wore. On his feet were a pair of old black work boots, not the Vuarnet boots he wore that day. Scattered across the floor of the display was hundreds of pistol and rifle calibre fired bullet casings. I was in the midst of photographing every last millimetre of everything my eyes landed on and because of the content we were writing at the time it took me about a year to get around to the pictures of the casings, imagine my surprise when I was seeing headstamps from 2001. How so?
I reached out to the museum (a notoriously difficult entity to deal with regarding this event) and was told that they were added for effect and were not from the event. You don't say?!
So the museum was a bust, nothing to find there, except, confusingly, a .40 cal casing laying on the seat of Sgt Haynes vehicle in the back yard. We left it there, it had zero relevance.

It was whilst speaking to an officer closely associated to this event I was shown a handful of spent casings that had been recovered from the original scene. Our first real lead.
The headstamps read 311/93, it was Norinco Yellow box.

Norinco 7.62x39mm recovered from the NHWD crime scene, dated 1993
Norinco 7.62x39mm 'Yellow Box'

The problem was that Factory 311 produced both lead and steel cored ammunition under the same headstamp. So whilst we could prove Chinese ammunition was used we were no closer to identifying what the composition of the pointy business end was.
Until, in amongst over 60GB of video given to us by a retired officers wife, we stumbled across what at first seemed like a generic 'reporter looking to fill some airtime minutes' piece. The reporter was outside of the bank several hours after the main portion of the event was over and he was grabbing folks that passed by him asking what they had seen, what they had heard etc. Pretty standard stuff. Until a young child approached carefully clasping some bullet fragments he had picked up out of the street. The reporter held open the young man's hand, and there on his palm lay the second major clue.

Apologies for the bad quality of the picture, but consideration must go 'to the fact that it is from twenty five year old film stock taken from VHS and transposed to digital, you tend to lose some sharp edges along the way.
Nestled in this young man's hand, among some flattened lead fragments, as you can see lay a steel core. A steel core with a blunt ogive. Where have we seen that before?

Civillian recovered artifacts from the firefight, note the steel core
Norinco 'Yellow Box' 7.62x39mm steel core projectile

An awfully small sample size, one out of approximately 1100, but we can only work with what we have in front of us. Star Sachs' of the Scientific Investigation Department's forensic report into the firearms and ammunition has never been made publically available, despite repeated requests to access said report we have consistently been rebuffed.
Anyway, slight saltiness at the LAPD's bureaucracy aside, several years ago I had the good fortune to be able to interview another officer that was front and centre for this event, in fact he was the officer to discharge the most rounds in the whole engagement. He is a wonderful gentleman to speak with and had many adventures after North Hollywood, some rather brutal in nature but his story is his story and not mine to repeat here as he has asked not to be publically identified. In the course of several interviews he showed the infamous Gene Blevins picture of Phillips with the HK91 under the Bank of America sign, and it struck me just how many people associated with this event have this picture on their wall somewhere, hell I even have a canvas of it above my desk too.

Gene Blevins infamous picture of Phillips weilding the Heckler & Koch Model 91

Dean's Tree, as seen in 2012
Yet this officer's presentation was different, it was framed behind glass, and in the bottom of the frame various copper jacket fragments, mangled lead chunks and steel cores. Finally we were seeing a slightly larger sample size.
So did Phillips use armor piercing ammunition? To the ATF's faulty classification, yes. To any logical firearms enthusiast's opinion, no, he just used cheap Chinese ammo that was only marginally better than bog standard lead core.
The final question comes back to the original question. How did Sgt. Haynes believe his statement was true when he made it?
Let us not forget that Haynes had been through the wringer that morning. Front and dead centre to the ongoing barrages in the initial engagement with Phillips, ducked behind his black and white that was the primary target, wounded in the left arm; an inch or two to the right and his story may have ultimately so much more serious, movement under fire with a fellow wounded officer to a position of cover and some concealment, being wounded a second time during that transition, to then have to watch as his fellow officer took a potentially fatal round through the thigh and the long agonizing minutes that crawled past as he could neither approach his downed fellow officer nor effectively negate the threat. Surely we can forgive him something he blurted out right?
This page is not about holding Sgt Haynes to task; the man performed a stellar job under the absolute worst of circumstances that the day had to offer. But again we have to ask why those words? What caused his belief that AP ammo was being used against him? Adrenaline for sure could have clouded his judgement, yet despite coming under sustained fire for many minutes, and although obviously agitated Sgt. Haynes never appeared to lose his composure on the 'tape'. So why when somewhat removed from that area of engagement did he all of a sudden come out with the fated quote?
We believe the answer is simple.
Haynes took cover behind the first tree on the northwest corner of Laurel and Archwood.
Whitfield was collapsed behind the third tree north of his position.
'Dean's Tree' as we affectionately coined it, has since been cut down by the city so further examination is no longer possible.

Luckily though period photographs exist, and show substantial bullet strikes to his tree.

Dean's Tree, alas no more. (2014)
Bullet strike to Dean's tree.

Haynes was first struck at approximately 09:26hrs whilst in position with his vehicle in the crosswalk of Laurel & Archwood, the bullet tearing through the outside of his left bicep.

Sgt. Haynes receiving medical aid, post shootout
At 09:27hrs he advised the PSR's whilst still under heavy gunfire that his wound was not serious. Also at 09:27hrs he told the PSR's not to send anyone to his position as he was still under fire. At 09:28hrs he reported that the civilians with him, Horen, Golding and Fisher we taking gunfire related injuries too.
At this point Officer Whitfield had also been struck, taking shrapnel injuries to his chest.
At 09:30hrs Phillips began his move from the ATM alcove to the North Lot.
There exists no transmission from Haynes or Whitfield between 09:27 and 09:30hrs indicating a change of position, yet interviews with Martin Whitfield stated that they saw that the bank robbers were starting to move northbound (actually only Phillips at that point but I think the slip can be forgiven given the circumstances) so deduction leads us to have Haynes and Whitfield abandoning their black and whites sometime between 09:27hrs and 09:30hrs, a mere three minutes at absolute most. They had been under almost constant fire for between three and five minutes.

7.62x39mm, left and .308, left
Haynes made it to tree #1, catching another round across his left leg on the way. Whitfield made it to tree #3 and remained there after being struck in the right thigh. Matasareanu, with a slight delay, followed Phillips to the North Lot, was struck twice by police gunfire and entered the bandit Celebrity by 09:32hrs.
Phillips performed his much documented run and gun in the North lot for approximately eight minutes with his original Norinco rifle.
At 09:38hrs Phillips reloaded the original Norinco and placed it in the trunk of the Celebrity and retrieved the H&K model 91. What had been a deadly confrontation of 7.62x39mm had now been replaced with a more powerful .308.

Both Haynes, at his tree, and Officer Richard Zielinski on the opposite side of Laurel Canyon Boulevard outside the Del Taco store engaged in a deadly game of whack-a-mole with Phillips. One would shoot, and then enter cover when Phillips returned fire and whilst the masked gunman was preoccupied the other officer would line up several shots. This was done to keep Phillips attention away from the stricken Whitfield.
'Dean's Tree' was potentially struck by two different ammunition calibres, both 7.62 from the Norinco and also .308 from the H&K.
Had Haynes heard the more substantial muzzle report of the H&K, seen the damage it was doing to the tree he sheltered behind, and believed that a different style of ammunition was being fired at him? It would seem the only logical explanation for such a statement to be made. In a high pressure situation and fighting for his life it would appear he had misinterpreted the fact that Phillips had changed rifles. A simple but yet certainly forgivable misunderstanding.

So whilst the myth of AP ammunition persists to this day, it is only partially in my humble opinion, true.
True armor piercing? No, I cannot in good conscience say that it was! No evidence exists, either implied or substantive of true AP ammunition use.
Armor piercing classified by a political need to go toe to toe with the Chinese over flooding the country with firearms and ammunition that were quite often used in tragic events by unstable people? You betcha.