This is the week network TV turns to the over-50 set scoring in the 60s. Sixth annual Legends of Golf starts today at Onion Creek in Austin; final two rounds of the $485,000 invitational for two-man teams make NBC Saturday and Sunday. Last year, Sam Snead and Don January paired to birdie every other hole, as it were, going 27 under par for 54 holes (one round rained out). Arnold Palmer has Dow Finsterwald as partner again; Gene Sarazen at age 82 has yet another go.

Snead, 71, arrived ready to "give the kids a lesson."

Evidently. On 135-yard hole No. 2 in the pro-am preliminary yesterday, Snead's eight-iron, off the famous smooth swing, sent the ball onto the front of the green--and rolling dead into the hole. Snead turned to caddie Creamy Carolan and said, "Well, that's No. 25." The 25th hole in one of his Legendary career . . .

The PGA Tour is in Texas, too, for the Byron Nelson Classic in Irving. Tom Watson won the Nelson four times at Preston Trail and Jack Nicklaus twice; now they tee at brand-new Las Colinas, 7,002 yards, par 71 and--this week--windswept. Las Colinas' first green is shaped like the state of Texas, with an Oklahoma-shaped bunker and a Gulf of Mexico water hazard . . .

Capital's charity golf season in full swing. Vinny Giles, Marty West, Buddy Marucci, Dave King among multititled amateurs entered in Bobby Abbo's 15th annual Poor Roberts Classic May 6 at Prince Georges Country Club. Shotgun start, no charge to spectators . . . Boys' and Girls' Clubs of Greater Washington benefit from three-day event at Poolesville Golf Club May 4-5-6. First day, pro-member. Then, celebrities and $50-a-head competitors. It's in conjunction with sponsor's Family Life Center opening . . . Third annual Boy Scouts Classic, May 13 at Montgomery Village, jointly sponsored by Middle Atlantic PGA and National Capital Area Council of BSA; Tip O'Neill and Abe Pollin honorary chairmen. . . . And, last call for Redskins Alumni celebrity event May 1, Indian Spring.