Q.1: This struck me as a fairly extreme claim. Is it true that the V2 production killed more than its use?
In all likelihood, yes. The director of the Mittelbau-Dora commemoration site is quoted with
According to Jens-Christian Wagner, director of the Mittelbau-Dora concentration camp memorial site, it "killed more prisoners in the production of the weapon than [other victims] in their deployment. This is unique; I don't think there was any other weapon that claimed so many lives during the production."
WP: Aggregat 4
In that article some numbers are given as:
Between September 1943 and April 1945, 16,000 and 20,000 concentration camp prisoners and forced laborers, most of them twenty to forty years old, died in the Mittelbau-Dora camp complex, on liquidation or so-called evacuation transports, according to conservative estimates. Approximately 8,000 people lost their lives using the weapon, most of them in the London and Antwerp area.
And that is the standard view:
Because of the conditions, deaths in the tunnels between November 1943 and March 1944 numbered almost three thousand. Beyond this toll, there were also another three thousand “muslims” (Muselmänner), prisoners unable to work because of grave illness, injury, or psychological shock. ese men were sent on to Bergen-Belsen or Maidanek with little chance of survival. […]
The completion of the barracks with washrooms in the spring and early summer of 1944 and other accommodations, including a sick bay staffed by medical personnel, while not adequate, was a large improvement over the murderous conditions of the tunnels. The number of deaths fluctuated drastically, lowering when the conditions improved and rising when new transports of prisoners arrived from the East.
Of the more than 5,000 V-2 rockets assembled in Kohnstein by the prisoners of Mittelbau-Dora, 1,500 of them landed in London and Southeast England, killing more than 2,000 people. Another 1,500 V-1 and V-2 weapons were aimed at Antwerp, Belgium, killing almost 7,000. It would appear that more prisoners died in the concentration camp serving Mittelwerk and further development of the “wonder weapons” than did helpless civilians in Germany’s enemy countries.
Gretchen Schafft & Gerhard Zeidler: "Commemorating Hell. The Public Memory of Mittelbau-Dora", University of Illinois Press:
Urbana, Chicago, and Springfield, 2011.
So it depends on your point of view of what you'd call "producing it". Most forced labourers did not die tightening a screw and slipping. Many died of sickness, hunger, malnutrition, maltreatment, overwork and total exhaustion etc.
From a rational strategists point of view that seems like an idiotic approach. Within Nazi ideology that views those lives not only as expandable but to be exterminated eventually anyway, if not through labour than by other means, this would make perfect sense. A Nazi would conclude that a V2 was an extremely effective weapon, killing only enemies and that already when still manufacturing it.
Given that not only the one concentration camp was involved in manufacturing the rocket, the death-toll for the rocket on German soil is likely even higher than most estimates:
In total, around 60,000 prisoners passed through the Mittelbau camps between August 1943 and March 1945. The precise number of people killed is impossible to determine. The SS files counted around 12,000 dead. In addition, an unknown number of unregistered prisoners died or were murdered in the camps. Around 5,000 sick and dying were sent in early 1944 and in March 1945 to Lublin and Bergen-Belsen.
WP: Mittelbau-Dora concentration camp
Q.2: Is the V2 unique in this statistic?
Difficult to answer unequivocally without further definition. The V2 is fairly unique in a number of categories. Depending on point of view: yes and no.
Given that the V2 killed more prisoners – or people working for Germany – than enemy civilians one might rephrase the question to whether any other weapon killed more of its own people in some kind of broad interpretation of friendly fire?
The answer to that might be found in Amerithrax attacks. American made weapons grade anthrax was never used against official enemies, but against
Stevens, Bob - photo editor at American Media Inc, dies of inhalation anthrax, October 5, 2001
Curseen, Joseph Jr. - DC area postal worker, dies of inhalation anthrax, October 22, 2001
Morris, Thomas Jr. - DC postal worker, dies of inhalation anthrax, October 21, 2001
Nguyen, Kathy - employee at Manhattan hospital, dies of inhalation anthrax, October 31, 2001
Lundgren, Ottilie - Connecticut woman, dies of inhalation anthrax, November 22, 2001
Also compare that to Anthrax: full list of cases.
Similarly, it is believed that the United Kingdom never used nerve gas in a war. But manufacturing it seems to have caused up to 41 deaths and many more injuries:
The Ministry of Defence is reopening a 30-year-old inquiry into a series of deaths and serious illnesses at a chemical weapons factory in Cornwall amid accusations that the original report was the subject of a high-level cover-up.
The new analysis could show that, for decades, civil servants fed false figures to ministers who then rehashed old answers to a succession of local MPs, she said. "The 41 deaths have always seemed a much higher than average death rate to me. I found it extraordinary the MoD has always alleged it isn't."
Robert Mendick: "Deaths Inquiry at Nerve Gas Plant", Independent, 7 May 2000.
Do we all remember the use of smallpox in war by the Soviet Union?
[…] The smallpox formulation—400 gr. of which was exploded on the island—"got her" and she became infected. After returning home to Aralsk, she infected several people including children. All of them died. I suspected the reason for this and called the Chief of General Staff of Ministry of Defense and requested to forbid the stop of the Alma-Ata-Moscow train in Aralsk. As a result, the epidemic around the country was prevented. I called [future Soviet General Secretary Yuri] Andropov, who at that time was Chief of KGB, and informed him of the exclusive recipe of smallpox obtained on Vozrazhdenie Island.
WP: Aral smallpox incident
Making use of smallpox in war by the Soviet Union death count zero against a really undisclosed number of casualties, three officially.
The use of anthrax again, this time by the Soviet Union, is also zero, but the numbers killed by it on friendly soil are around 100. (WP: Sverdlovsk anthrax leak, 1979.)
If we go for an individual weapon alone then the atomic bomb also makes the list. A death toll of zero from the first explosion stands against the death of Harry Daghlian and Louis Slotin.
The V2 may stand out as among the weapon with the highest death toll, according to the criteria, and having been even envisioned and almost designed to kill workers in the process of manufacturing it. But producing weapons is inherently dangerous. Producing them without using them as originally intended should automatically make them contenders for the list. The V2 is in one way certainly not unique. Its older brother, the fastest Volkswagen at the time, the V1 was also built by forced labour, but had after a while quite low death toll around the intended targets, as those bombs had abysmal accuracy and the countermeasures improved greatly.
A total of 6876 long-range weapons struck English soil. 8938 people were killed and 24 504 injured.
Belgium was hit by 8661 long-range weapons. Here 6448 people were killed and 22 524 injured.
Dieter Hölsken: "Die V-Waffen. Entwicklung und Einsatzgrundsätze", Militärgeschichtliche Mitteilungen; Freiburg Bd. 0, Ausg. 2, (Jan 1, 1985): 95. p 116.
Bringing the effective death toll to 15386 and 47028 people injured by those weapons.
Hölsken calculates that in total 22384 V1 and 3170 V2 were fired at the enemy. Curiously 11 V2 were targeted on German soil. None of the V2 used managed to hit that target.
Since the German war machine depended heavily on slave labour that should also exterminate the workers, a look on further candidates that were produced and brought to the frontline without killing much people might yield a few more, like: Krummlauf, Schwerer Gustav (as Dora), V3, but hard numbers for comparison seem unavailable.
Globally, there might be another twist to definitions. Some items and implements are classified as "defensive weapons", like shields and walls, and while those are surely not covered by the definition sought after in the question, it looks like they pretty much all would qualify. Whether Chinese Wall, Limes or Maginot…
The death toll in manufacturing V1 and V2 weapons is for one concentration camp alone between 12000, officially registered by the SS in the camp, with a number more probably around 20000. That number does not include other deaths in the other camps and over 50 supplying factories, companies or "transport losses", whether by train or on death marches from the East.
Compared to 15386 losses of enemy civilians the claim holds up. As the claim over-focusses on the V2 it is unproblematic to deny its uniqueness. The V1 can be seen as equally responsible for more deaths in production and perhaps even less effective if loss of human life is seen as the goal.