Zoi Constantine writes for The National:
His phone rings almost non-stop, and he can barely keep up with the demand for his goods.
The war next door in Syria has been good for the Lebanese arms dealer, and the clamour from his phone promises it is going to get even better.
As the fighting in Syria escalates and pressure grows on the international community to provide the means for Syrians to repel the onslaught by government forces, his rocket-propelled grenades and AK-47 assault rifles become more precious commodities by the day.
Asked where the weapons are bound, Abu Jihad, who asked that his real name not be used, placed his hands over his eyes in a display of mock ignorance.
Then he says: "Everyone knows where the weapons are going --- to the Jaish Al Hurr [Free Syrian Army].
"At the end of the day, we are trying to make money and to look after our families … I say, just give me the money and take what you want. No problem."
A year ago, an RPG went for US$1,000 (Dh3,670), now it's $2,000. AK-47s have jumped from $1,500 to $2,300.
Technically, it is illegal in Lebanon to sell such weapons, but in a country that suffered through a 15-year civil war that ended in 1990 and still is afflicted by sectarian clashes, stocks are easy to come by.
For the Free Syrian Army, that is good news.
Unable to defect from government army ranks with much more than small weapons, members of the rebel force fighting to depose Bashar Al Assad as president are using donations from Syrians abroad to buy guns and ammunition from neighbouring countries such as Lebanon and Turkey.
"It's natural that when there's armed conflict they're going to try to buy weapons in the country next door. I am selling so much," said Abu Jihad, who is in his forties.
He has several arms depots. At one of his stores in a residential neighbourhood in Beirut, he glances around cautiously before opening the metal doors to a dingy room with blue walls.
Inside the small storage room, AK-47s and RPG launchers are propped against the walls. Rocket-propelled grenades are laid in rows on the floor, beside bayonets and camouflage combat belts. Bullets are spread out on a workbench at the back of the room, opposite a cabinet with small drawers full of other ammunition and ordnance.
"Business is booming," he says, apparently intending no pun.
Abu Jihad does not sell directly to armed Syrian opposition groups, but to a series of middle men who move the weapons to Lebanon's border with Syria and then across to the rebels.