The armaments were found by special forces in the Zormat region of Paktia province bordering Pakistan during operation Warrior Sweep, which began on Tuesday.
The operation has also involved US airborne and Italian mountain troops, as well as 1000 soldiers from the fledgling Afghan National Army on their first major combat operation.
Colonel Rodney Davis, a spokesman for the US military in Afghanistan, said this week the aim was to aggressively seek out and attack Taliban, al-Qaida and other anti-American forces.
Davis was asked on Friday whether US forces had found any guerrillas, he replied: "No, there has been no contact."
However, he added: "The operation is going well."
Elsewhere in Afghanistan on Friday, six police officers were wounded, two seriously, when their vehicle hit a landmine laid by suspected Taliban fighters about 50 km east of the southern city of Kandahar, police and hospital officials said.
"The operation is going well"
Colonel Rodney Davis
In another incident about 5 km from Kandahar, a soldier was wounded by a mine while chasing fighters who fired a rocket at a government post, provincial police chief General Akram Khan Faizwal said.
Davis said the arms caches discovered, included machineguns, hundreds of shells, rockets and mortar bombs and thousands of rounds of machinegun ammunition.
The latest operation follows stepped up attacks by suspected Taliban fighters on the US-led troops in Afghanistan.
Nine soldiers were wounded last weekend, the US military said it killed up to 24 suspected Taliban fighters near the Pakistani border last Saturday.
Afghan officials say attacks have been mounted by Taliban fighters who have infiltrated from Pakistan, an open backer of the group before joining the US-led "war on terror" in 2001.
On Thursday, the coalition sent a B-52 bomber and Harrier planes to bomb guerrillas who rocketed a US base in the east of the country close to the Pakistani border.
About 11,500 US-led troops are in Afghanistan pursuing remnants of the Taliban and al-Qaida network blamed for the September 2001 attacks on the US.