Transient burning characteristics of an aluminized ammonium perchlorate - hydroxyl-terminated polybutadiene (AP-HTPB) based base bleed propellant was investigated experimentally. The transient instability experienced by the propellant due to sudden depressurization at the moment the projectile leaves the gun muzzle was physically simulated in a quench bomb. Experiments were conducted at an initial chamber pressure of 70 bar, 120 bar, 180 bar and 240 bar. There was a minimum critical depressurization rate observed above which the AP/HTPB base bleed propellant quenches, which increased with the maximum chamber pressure following the relationship of |dP/dt|_critical = 0.2927 P^1.2257 where P is in bar and |dP/dt|_critical is in kbar/sec. The performance was compared with a typical pyrotechnic ignitor like Boron Potassium Nitrate ( BKNO3 ) which did not quench within the experimental limits on dP/dt that the setup provided. The BKNO3 samples were able to endure depressurization rates as high as 459 kbar/sec for initial pressures of about 240 bar, without quenching. Typical depressurization rates experienced in a 155 mm, 38 calibre Bofors gun is around 200 kbar/sec as the shell leaves the gun and base pressure remains around 725 bar. Thus the quench bomb closely simulates the depressurization conditions and the BKNO3 based pyrotechnic igniters can be safely used for the ignition of base bleed systems. The maximum depressurization rates obtained with BKNO3 were 83.95 kbar/s at 70 bar and 205.0 kbar/s at 180 bar whereas critical depressurization rates obtained for the propellant were 45.0 kbar/s and 200.0 kbar/s at the corresponding pressures.