Authorities have not yet disclosed what kind of firearms were used by Mr Paddock in the devastating attack on Sunday night, although reports suggest the 64-year-old had 23 guns in his Mandalay Bay hotel room and even more in his Nevada home.
Massad Ayoob, a firearms expert, instructor and author, believes the rapid pace of the gunfire means the shooter may have used a fully automatic weapon, also known as a machine gun, to carry out the massacre.
However, obtaining a machine gun in the US requires special permission from the Treasury Department, as well as an FBI background check and approval from the buyer’s local police department.
Civilians have been banned from possessing newly made automatic weapons since 1986, although those made before then can still be purchased, and can cost around £15,000 ($20,000).
As of April this year, 630,019 machine guns were registered to civilians and police forces in the US ─ including 11,752 in Nevada.
However, weapons expert Mr Ayoob believes the gunshots “did not sound as consistent” as he would typically expect from a fully automatic weapon, such as an M-16 or AK-47.
He added: “The pace of fire is a little bit erratic. At one point it’s slower than it is at another point.”
However, a semi-automatic rifle, which fires one round of ammunition with each pull of the trigger, would have been relatively easy for Mr Paddock to obtain.
Mr Ayoob believes the gunman may have attached a device to a semi-automatic gun to make it fire more rapidly.
He added: “It’s faster than almost any human being is going to be able to pull a trigger on a semi-automatic.”
Paddock may have used a Hellfire or a bump-fire device, which would allow him to produce a faster firing rate – but these are not very popular and mean the weapon is often less accurate, according to Mr Ayoob.
However, accuracy was not really an issue for Mr Paddock as he began “hosing a two-acre area with 30,000 targets”.
Two Nevada gun shops have also revealed that they sold firearms to Mr Paddock last year after he passed all required background checks.
Whether the weapons bought from the gun shops, New Frontier Armory in North Las Vegas and Guns and Guitars in Mesquite, were used in the Las Vegas attack remains unclear.
David Familglietti of New Frontier said Paddock purchased a rifle and a shotgun earlier this year.
He told NBC News: “The rifle was not fully automatic, and a shotgun isn’t capable of shooting from where he was.
“He’s only shopped there once, so it wasn’t someone we knew personally.
“We’re very sad about the news of this tragedy. We’re in the business of selling firearms legally and took all precautions on this sale, as we do with all sales.
“My staff takes their job very seriously, and if there were any ‘red flags,’ the sale would have halted immediately.”
Nevada gun laws are among some of the most relaxed in the US. People are allowed to carry weapons and do not even have to register themselves as owners.
Background checks are done when people buy guns from stores but there are no requirements for buying and selling guns privately.
There are no limits on purchasing ammunition and no bans on semi-automatic firearms.