I got 5-6 shots with these entering the military. All but one felt like a normal shot if anything. The last one felt like I was jabbed with an knife and bled se

I got 5-6 shots with these entering the military. All but one felt like a normal shot if anything. The last one felt like I was jabbed with an knife and bled severely. Afterwards, I was told if the gun is flush + perpendicular to the muscle, it's fine but if it's at an angle or not held still it cuts as it moves.