HEAT grill to medium-high heat.
MIX meat, bread crumbs, egg and 1/4 cup barbecue sauce just until blended; shape into 4 (1/2-inch-thick) patties.
GRILL 5 to 6 min. on each side or until done (160°F), brushing with remaining barbecue sauce for the last 2 min.
FILL buns with burgers, lettuce, tomatoes and onions. Serve with pickles.