Say what you want ... that is a great group you shot there. 40 yards or not. And open sights. Boy an I glad I am off the hook for that barrel. I was loosing a lot of sleep over it.
Today I started out shooting two 50 grain pellets and the 375 grain Buffalo Bullet SSB. I (like you ) like to shoot a five shot group. It did very well with the pellets. I then went to 100 grains of loose Pyrodex RS and started to shoot a five shot group but was having so much fun I forget to stop. I just kept shooting.
I then switched targets. I found some 350 grain Saber Tooth Conicals and loaded 100 grains of loose Pyrodex RS under them. I had one get away from me, but that was my fault. Just as I squeezed the trigger, the rifle slipped on the wet bench rest. Not much mind you but enough. When I was shooting that group I also realized instead of concentrating on the center of the bull I was focused on the bullet hole. So they started to walk on me.
When shooting the 302 grain Buffalo Bullet sabots, I was not swabbing the barrel. I was shooting Goex 3f in a 100 grain charge. Shot #4 loaded so hard I thought I would bend the range rod or have to hammer it down the barrel. It got into the barrel then seemed to stick on something. I then swabbed and fired the fifth shot. The strange thing is when I looked at the four shot group of them, I can only find three holes. That means I have a real tight group there, or I missed the target completely.