Question: What type of gun did Princip use to assassinate Franz Ferdinand?
About the article "Assassination of Archduke Franz Ferdinand of Austria", section "Shot dead".

Candidate passages:
  Nedeljko Čabrinović, for conspiring to assassinate Archduke Franz Ferdinand  Vaso Čubrilović, for conspiring to assassinate Archduke Franz Ferdinand  Veljko Čubrilović, for conspiring to assassinate Archduke Franz Ferdinand  Trifko Grabez, for conspiring to assassinate Archduke Franz Ferdinand  Danilo Ilić, for conspiring to assassinate Archduke Franz Ferdinand  Muhamed Mehmedbašić, for conspiring to assassinate Archduke Franz Ferdinand  Cvjetko Popović, for conspiring to assassinate Archduke Franz Ferdinand  Gavrilo Princip, for assassinating Archduke Franz Ferdinand  Nazario Sauro, for fighting for Italy in the First World War  
  Dragutin Dimitrijević Apis, leader of Black Hand organization.
Gavrilo Princip, Bosnian Serb nationalist, assassin of Archduke Franz Ferdinand of Austria  Nedeljko Čabrinović, one of the men sent to assassinate Archduke Franz Ferdinand of Austria  Trifko Grabež, one of the men sent to assassinate Archduke Franz Ferdinand of Austria  Vaso Čubrilović, one of the men sent to assassinate Archduke Franz Ferdinand of Austria  Cvjetko Popović, one of the men sent to assassinate Archduke Franz Ferdinand of Austria  Danilo Ilić, one of the men sent to assassinate Archduke Franz Ferdinand of Austria, the leader of the 8 men  Veljko Čubrilović, one of the men sent to assassinate Archduke Franz Ferdinand of Austria  Puniša Račić, parliament assassin of Stjepan Radić  Jovo Stanisavljević Čaruga, outlaw  Zvezdan Jovanović, former member of the Serbian special police, assassinated Serbian Minister Zoran Đinđić  Mijailo Mijailović, Swedish psychopath, assassin of Swedish Foreign Minister Anna Lindh  Arkan, warlord, organized cime  Kristijan Golubović, organized crime  Pink Panthers, jewel theft network  
When it was announced that Archduke Franz Ferdinand, the heir to the throne of Austro-Hungarian Empire, was going to visit Bosnia and Herzegovina in June 1914, Colonel Dragutin Dimitrijević, the chief of the Intelligence Department in the Serbian Army and head of the Black Hand, sent seven men, Grabež, Nedeljko Čabrinović, Vaso Čubrilović, Cvjetko Popović, Danilo Ilić, Muhamed Mehmedbašić and Gavrilo Princip to Sarajevo to assassinate him.
Each man was given either revolver or a bomb and a small vial of cyanide.
They were instructed to commit suicide after Archduke Franz Ferdinand had been killed.
It was important to Colonel Dimitrijević that the men did not have the opportunity to confess who had organised the assassination.
Grabež, Nedjelko Čabrinović, and Gavrilo Princip, were all suffering from tuberculosis and knew they would not live long and the other four men hated Franz Ferdinand.
They were therefore willing to give their life for what they believed was a great cause: Bosnia and Herzegovina achieving independence from Austro-Hungary.
Nikola Pašić, the prime minister of Serbia, heard about the plot and gave instructions for Grabež, Princip and Čabrinović to be arrested when they attempted to leave the country.
However, his orders were not implemented and they managed to reach Bosnia and Herzegovina where they joined forces with fellow conspirators, Vaso and Veljko Čubrilović, Muhamed Mehmedbašić, Danilo Ilić and Cvijetko Popović. 
Danilo Ilić (1891 – 3 February 1915) was a Bosnian Serb, born in what is modern-day Bosnia and Herzegovina.
He attended the State Teachers' College in Sarajevo and for a while taught at a school in Bosnia.
In 1913, Ilić moved to Belgrade where he became a journalist and a member of the Black Hand secret society.
Ilić returned to Sarajevo in 1914 where he worked as editor of a local Serb newspaper.
He became a member of Mlada Bosna ("Young Bosnia").
He recruited Gavrilo Princip, Nedeljko Čabrinović, Vaso Čubrilović, Trifko Grabež, Muhamed Mehmedbašić, and Cvjetko Popović to assassinate Archduke Franz Ferdinand of Austria.
He and Gavrilo Princip were close friends.
On Sunday, 28 June 1914, Franz Ferdinand and Sophie von Chotkow were assassinated by Gavrilo Princip.
Princip and Nedeljko Čabrinović were captured and interrogated by the police.
They held out, but Ilić, who was picked up on a routine check, eventually broke down under pressure and named his fellow conspirators.
Muhamed Mehmedbašić managed to escape to Serbia but Veljko Čubrilović, Vaso Čubrilović, Cvijetko Popović and Miško Jovanović as well as Danilo Ilić were arrested and charged with treason and murder.
Eight of the men charged with treason and the murder of Archduke Franz Ferdinand were found guilty.
Under Austro-Hungarian law, capital punishment could not be imposed on someone who was under the age of twenty when they had committed the crime.
Nedjelko Čabrinović, Gavrilo Princip and Trifko Grabež therefore received the maximum penalty of twenty years, whereas Vaso Čubrilović got 16 years and Cvijetko Popović 13 years.
Illić, Veljko Čubrilovic and Miško Jovanović, who helped the assassins kill the royal couple, were executed at the Sarajevo barracks on 3 February 1915. 
Emperor Franz Joseph ordered Archduke Franz Ferdinand of Austria, heir presumptive to the Austro-Hungarian throne, to attend military exercises scheduled for Bosnia in the summer of 1914.
After the exercises, on June 28, 1914, Franz Ferdinand toured Sarajevo with his wife, Sophie, Duchess of Hohenberg.
Six armed irredentists, five Serbs and one Bosnian Muslim, coordinated by Danilo Ilić, lay in wait along Sarajevo's Appel Quay because it was announced that Franz Ferdinand's motorcade would use that route.
At 10:10 AM, Nedeljko Čabrinović bombed Franz Ferdinand’s motorcade as it approached the Čumuria bridge.
Twenty people were wounded, but Franz Ferdinand was unhurt.
The bomb thrower had been instructed in Belgrade by Serbian Major Voja Tankosić to take potassium cyanide to prevent his capture.
Čabrinović swallowed the cyanide, but it only sickened him.
The Sarajevo police arrested Čabrinović and brought him to the police first aid post.
Investigator Judge Leo Pfeffer was at the police station and was immediately assigned to investigate.
Before the investigation got far, news arrived that Gavrilo Princip had shot and killed Franz Ferdinand and Sophie while they were on their way to visit the wounded in the hospital.
Princip took his cyanide, but the cyanide had the same effect on Princip as it had on Čabrinović.
The police arrested Princip, and he too was brought to the first aid post.
Within 45 minutes of the shooting, Princip began telling his story to Pfeffer.
By the next day, June 29, 1914, based on the interrogations of the two assassins, Oskar Potiorek, Governor of Bosnia-Herzegovina, was able to telegraph to Vienna that Princip and Čabrinović had conspired in Belgrade with the comitaji Milan Ciganović and others to obtain bombs, revolvers, and money to kill Franz Ferdinand.
A police dragnet quickly caught most of the conspirators.
Twenty-five people went to trial, but nine were acquitted.