Hadafi, representing Police, posted 688.5 points to finish ahead of Armed Forces' Ezuan Nasir Khan (686) and Kedah's Zaizi Zakaria (678.8).
The Penang-born shooter, however, will only compete in the 50m prone and three-position in his Sea Games debut.
Hadafi is now hoping the National Shooting Association of Malaysia will also register him for the air rifle in Laos after yesterday's achievement.
"I would love to compete in all three rifle events, including in the air rifle.
"I have done well so far in the air rifle, having also won the team bronze in the recent SEASA (Southeast Asian Shooting Association) Championships in Bangkok," said the 24-year-old at the Subang Shooting Range yesterday.
|Hadafi Jaafar won the 10-metre air rifle gold in the National Shooting Championships in Subang yesterday. — Pic: MOHD YUSNI ARIFFIN|
On his Sea Games target, he said he would try his best to win a few medals.
"Thailand and Vietnam are the dominant forces in men's rifle and they will win most of the medals in the Sea Games.
"As it will be my first Sea Games, I cannot expect much. Even earning a bronze will be considered a personal achievement," said Hadafi, who picked up shooting when he joined the police force in 2005.
Meanwhile, Perak's Hasli Izwan Amir Hasan came close to equalling Sabiamad Abd Ahad's 14-year-old record in the 25m centre fire event.
Hasli Izwan, who competed in last year's Beijing Olympics, shot a 99-97-96-98-97-97 series for a total of 584 points to win the event.
Armed Forces took silver and bronze through Ridhuan Mohamed (563) and Zulkefli Ismail (561) respectively.
RESULTS -- Men's 10m air rifle: 1 Hadafi Jaafar (Pol) 688.5 pts, 2 Ezuan Nasir Khan (AF) 686.0, 3 Zaizi Zakaria (Ked) 678.8;
Team: 1 Armed Forces 1,723, 2 Police 1,718, 3 Pahang 1,712.
25m centre fire pistol: 1 Hasli Izwan Amir Hasan (Per) 584, 2 Ridhuan Mohamed (AF) 563, 3 Zulkefli Ismail (AF) 561;
Team: 1 Armed Forces 1,684, 2 Police 1,659.
Women's 50m rifle 3-P: 1 Nur Suryani Mohd Taibi (AF) 675.1, 2 Shahera Rahim Raja (AF) 669.1, 3 Nordaliah Abu Bakar (Pol) 662.4;
Team: 1 Armed Forces 1,714, 2 Police 1,696, 3 Pahang 1,668.- NST