The Registered HK Trigger Pack Makes Things Interesting

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It’s nothing more than a pressed steel box, yet the BATFE considers it a machinegun. Once you get the tooling sorted, any competent manufacturing facility could churn these things out by the thousands for a couple of bucks apiece. There are some distinctive holes here and there, but it really isn’t anything special. Why, then, might anyone be tempted to dump upwards of $50,000 for such a trinket? It’s all about supply and demand.

Prior to the National Firearms Act of 1934, there was no federal gun control in America. Anybody with a little money could pick up a full auto Thompson or a Colt Monitor BAR cash and carry without so much as a signature.

In the aftermath of Prohibition, newsreels were fat with lurid depictions of machinegun-wielding motorized bandits. Congress subsequently crafted the 1934 NFA. This fetid piece of unconstitutional offal established the current regulatory scheme governing machineguns, short-barreled weapons, sound suppressors, and destructive devices like cannons and grenades. The most onerous bit was the $200 federal transfer tax. In 1934, that would have been around $4,700 in today’s money. Most Americans would recoil at the thought of taxing a Constitutional right. However, apparently the Second Amendment doesn’t carry quite as much weight as the rest. Who knew?

The 1934 NFA shut down commerce in machineguns. That was the point. However, over time, inflation gradually began to take the teeth out of that $200 tribute. By the early 1980’s, the market for legally-registered machineguns was beginning to gather a little steam. In 1986, Reagan signed the ludicrously-titled Firearms Owners Protection Act. The FOPA made the further manufacture of automatic weapons for sale to civilians illegal. For the first time in American history, the government outright banned an entire class of firearms.

Previously-owned weapons were grandfathered. However, that fixed the supply. There are currently about 179,000 legally transferable automatic weapons in circulation. With each passing year, more young Americans turn 21 and become eligible to buy a transferable machinegun. The end result is basic economics—supply and demand. In fact, there have been some scholarly papers written about this weird artificial market.

The practical result is that the prices of those 179,000 transferable machineguns have steadily and methodically skyrocketed. The full auto M16 I bought in 1987 for $600 would take the better part of thirty grand to replace today. This means that shooters interested in taking the full auto plunge want their NFA purchases to be as versatile as possible.

Financial Flexibility

An M16 receiver or registered drop-in auto sear is actually a really good option. That single transferable M16 could become a pistol-caliber subgun, an assault rifle, or a belt-fed machinegun simply by mixing and matching upper receiver assemblies. However, the real top of the heap came from HK.

There were three routes to get there. The first was a registered receiver HK conversion of a semi-auto HK94 carbine done prior to the 1986 machinegun ban. These were specific individual firearms that were papered as machineguns. If done well, registered receiver conversions can be almost factory perfect. However, these conversions were committed to the one single chassis. An MP5 cannot become an HK23. As a result, they are, counterintuitively, usually a bit cheaper than the next two conversions are today.

These roller-locked HK weapons were designed from the outset to be modular. While the receivers were unique to each caliber, the trigger packs were common across everything from the diminutive MP5K all the way up through the belt-fed HK21 and HK23. As a result, a single registered trigger pack would allow you to coax full auto fire out of all of those sexy HK weapons. That versatility made these conversions ludicrously expensive.

Arguably, the simplest was a registered HK sear. These little stamped steel trinkets sold for around $35 apiece back before the ban. They’re $54,000 now. A registered sear can be installed in any HK trigger pack. The down side is that this takes a little fitting for reliable operation, and the sear can potentially wear over time.  The final alternative was to serialize the trigger pack itself—that simple steel box. The up side there is that you can swap out the entrails as needed. The pack itself is essentially indestructible. That thing will still be running when the sun burns out. As investments go, the pack is the most stable of the lot.

So, What Can You Actually 
Do with It?

The fire control housings on the MP5K, the G3, and the standard MP5 are all different. However, the internal trigger pack is common across all of these legacy HK platforms. It takes a little mill work to get the housing to fit around the oversized front mounting lug on semiauto guns, but you can undertake that with a Dremel tool in a pinch.

To convert most HK-style guns using a registered trigger pack, you need only swap out the bolt carrier and mount up the pack. Semi-auto bolt carriers lack the trip ramp that activates the full auto mechanism in the pack. Relatively speaking, GI-surplus bolt carriers are not terribly expensive, at least by HK standards. Modern HK clones that have the front fire control housing pushpin intact will also have an additional internal block to contend with. For the most part, however, a registered trigger pack is plug and play.

What Do They Cost?

The good news is that there’s never been a better time to find HK clone host guns. Century Arms (CenturyArms.com) and SDS Arms (SDSArms.com) some simply magnificent Turkish-made MP5 variants. Zenith makes them on this side of the pond as well. HK also sells a few, though they are really expensive and not actually as close to the original factory guns as are the Turkish versions. Regardless, the host gun is no longer the limiting reagent.

I hope you’re sitting down. According to Machinegun PriceGuide.com, as of the first quarter of 2024, registered receiver conversions averaged around $45,000–50,000. Sear conversions were running around $54,000. Registered fire control boxes are relatively unusual and subsequently difficult to assess with any accuracy. They typically cost about what sear conversions might.

I have a friend who is a long-time NFA dealer. He bought about 100 HK sears right as the law changed back in 1986 and then sold them incrementally as he needed cash. He has one left today. According to the Internet, here is a breakdown of the known HK sear and trigger pack conversions. I cannot vouch for the accuracy of these numbers, but I found them nonetheless thought-provoking.

An HK sear weighs 0.062 oz. At $54,000 that makes HK sears worth $870,968 per ounce. That’s 317 times more valuable than gold by weight. If you find yourself with a time machine and are looking for a hot investment opportunity, HK sears and trigger packs are tough to beat.

MANUFACTURER/NUMBER PRODUCED

TRIGGER PACKS

• LaFrance: 138 +/-
• DLO: 50+/-
• Alltec: 30 +/-
• C-Ray Systems: 18+/-
• Ozark Mountain
• Arsenal: <10
• RDTS: 6

REGISTERED SEARS

• Fleming Firearms: 3,500
• S&H: 2,000
• Qualified: 1,500
• Jonathan Ciener: 250

NOTE: The number of all of the registered trigger packs, sears, and fire-control housings were not available to the author from the following manufacturers, which also made them: ACP Arsenal, DLO, Group Industries, Hard Times Armory, Jonathan Arthur Ciener, Knights Armament, Neal Smith, S&H Firearms, Weapons Specialties, Wilson Arms, and others.

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