Ron I'd have to agree that those shots aren't very good. I'm not being critical just stating a fact. But keep practicing and you should easily cut that group size in half.
There are a couple tricks to improve your performance that I've learned from competitive shooting that should help.
Eliminate as much muscle tension as possible. Horizontal position: Shoulder your rifle with your eyes closed. You should be in line with your target. If not, adjust your foot position. Vertical position: Position your off hand on the forend closer or farther while resting your upper arm against your body.
Relax. Concentrate on your target. You will never hold your rifle dead solid. The trick is with practice to get the sights moving in ever tightening circles around the bull. With time this circle will become smaller and smaller.
And lastly don't snap the trigger when you're "on target" but rather squeeze the trigger applying more pressure only when you're on target. Let the shot surprise you.
This may all sound like basic instruction but its surprising how many do not do this.
But no matter how good you become it is always better, when possible, to use a support of some kind.
I don't have much of a problem shooting my caplocks or inlines off hand. But if I'm shooting a flinter, and my shots are over 50 yards, I will always use some kind of support, usually a tree, or go to a kneeling position.