thumb|upright|A NASA QF-106 Delta Dart from the Eclipse program shows its area ruled fuselage In 1972, some F-106As were upgraded in Project Six Shooter that involved fitting the F-106 with a new canopy without metal bracing which greatly improved pilot visibility.Donald 2003, p. 250. Also added was an optical gunsight and provision for a M61 Vulcan 20 mm cannon. The M61 Vulcan had 650 rounds of ammunition in the center of the weapons bay, being used in place of the AIR-2 Genie. Many F-106 units opted to fly without the gun, retaining their nuclear payload instead. The F-15A Eagle started replacing the F-106 in 1981, with "The Sixes" typically passed on to Air National Guard units. The F-106 remained in service in various USAF and ANG units until 1988.
thumb|upright|a nasa qf-106 delta dart from the eclipse program shows its area ruled fuselage in 1972 some f-106as were upgraded in project six shooter that involved fitting the f-106 with a new canopy without metal bracing which greatly improved pilot visibilitydonald 2003 p 250 also added was an optical gunsight and provision for a m61 vulcan 20 mm cannon the m61 vulcan had 650 rounds of ammunition in the center of the weapons bay being used in place of the air-2 genie many f-106 units opted to fly without the gun retaining their nuclear payload instead the f-15a eagle started replacing the f-106 in 1981 with "the sixes" typically passed on to air national guard units the f-106 remained in service in various usaf and ang units until 1988