Charles Weaver, a 24-year-old native of Fairfax County, rode Stocking Stuffer to first place in the $5,000 Upperville Hunter Classic today, collecting his 10th victory this week aboard various horses.

Weaver won the Founders Cup Friday with King's Kindness and took second place in the Cup event riding Stocking Stuffer, an 8-year-old bay gelding owned by Mr. and Mrs. August A. Busch Jr. Stocking Stuffer also was the Grand Champion of last year's Upperville Colt and Horse Show.

Weaver also guided Ruzton, a 6-year-old bay geling owned by Robert Baskowitz, to fourth place in the Hunter's Classic today. He won two other classes in the working hunter division with the horse this week.

The young rider also won all five classes in the green conformation division and the first-year green working class in compiling his unusually high number of victories. He will not be competing Sunday, the final day of the show, when the $15,000 Upperville Jumper Classic is run.

Stocking Stuffer, seventh in a class of 11 in the hunter event, scored highest in the first round of competition, earning a 94.5 point average of a possible 100, after flawlessly scaling 12 obstacles ranging in height from four to 4 1/2 feet.

Stocking Stuffer was preceded by San Selipe, ridden by Rodney Jenkins. San Selipe, a gray gelding that won last year's Hunter Classic, trailed slightly in the first round with a 92.75 point average.

Stocking Stuffer preceded San Selipe in the second round, which consisted of jumps over eight obstacles ranging up to 4 feet 9 inches, and earned a 91-point average for a final average of 92.75.

It appeared the two horses and their riders might end in a dead heat until San Selipe failed to scale the second fence, tumbling with rider Jenkins. Neither the rider nor the horse was injured seriously, but they did not complete the course.

Jenkins, who rode five horses today and finished second atop Riot Free with an 87.75-point average in the Classic, said San Selipe's fall resulted from starting the jump too soon. No Penalty, ridden by Patricia Heucheroth, finished third with a final average of 86.265.

Weaver, who had not ridden Stocking Stuffer before this show, said the horse was schooled for it by jumping over demanding fences. He said the course here, designed by Bertalan deMemethy, coach of the U.S. Olympic equestrian team, is the most difficult he has ridden in the country.

Two members of that team, William Buddy Brown and Dennis Murphy, will be competing Sunday in the Jumper Classic, the finale of the week-long show. The event begins at 1:30 p.m. at the Salem Course, opposite this week's main course, on Rte. 50 in Upperville.