As I see it there are three things you have to do to become a good offhand shot.
First you have to establish your shooting position so that when in a relaxed mode the rifle points naturally to the target. This is known as your Natural Point of Aim or NPA. This can be shown to you in a general way but everybody is enuf different that you'll have to find your exact position for yourself. Basically, if you have to "push" the rifle in any direction to accomplish this you need to adjust your stance a bit more. When out of position you just put strain on your system and in a 100 shot match you'll be tired out before you're halfway there.
Your feet should be about shoulder width apart. This will vary with individuals but is a good starting place till you develop your own personal stance. Foot placement, if your right handed, should have the right foot 90 degrees to the target and the left foot about 45 degrees to it, and your body turned slightly away from it. With the Schuetzen rifles we use we have to use a slightly less body angle to the target than modern rifle shooters use.
Second is physical conditioning. The older you get the more important this becomes. A full body work-out is best because you want to strengthen the legs, trunk, and upper body in order to be able to hold the gun as steady as possible. It is physically impossible to hold the gun perfectly still, but thru proper exercise this can help reduce this to a minimum. Jogging or power walking is very good in that it increases your lung capacity and will allow you to "hold" longer before becoming winded. The old timers had a saying about this..... If you have to run for the train you might as well stay home. In other words. Stay calm and don't let anything bother you, before, on the way to, or during the match, as if you get all worked up about something it'll be just that much harder to shoot well.
Third is mental training. You have to develop a method that allows you to focus on the sights rather than the target and to shut out everything not applicable to what you are doing. This is the one thing that's very hard to explain. I tried to explain the two methods I'm aware of in another post so won't get into that here. Look at it as an application of Zen. This is something that only comes over time, and will vary with individuals depending how "nervous" a personality they are.
Trigger control comes under this to. If you consciously tell yourself to squeeze the trigger, you're to late. The gun will already have moved off where you want to have the shot hit. The best practice for this, as well as the other phases of shooting offhand, is using an air rifle. Barrel time is almost twice that of a .22 and a third of a CF rifle so an unconscious trigger release is mandatory. I always tell people if they consciously make the shot happen it's an automatic 7 or worse.
Another part of mental training is knowing where every shot went before you look thru the spotting scope. If you can't reasonably tell where the shot hit on the target you weren't focused on what you were doing. Without this part you can't tell what you're doing wrong. Good shots can tell exactly what ring and o'clock the bullet hit without looking. After the shot, and before the score was signaled, Hudson in his record setting score turned to the audience and said, "I win!". He knew exactly where that shot went. The better you are at this the better that offhand shot you'll be.
We can, of course, throw in a fourth item to better offhand shooting, and that's practice....... but you all knew that, didn't you?
The more you do the more easily all the above will become second nature. I'm sure you've all had a shot, when it broke, you just KNEW that it was a 25. Make that happen every shot and you'll be hard to beat. But, it takes practice, and more of it than most will want to put into it.
This will give you, in a general way, an idea of how difficult it is to become really good at offhand shooting. The sad part is that not everyone is created equal either. Some are more naturally suited to it thru temperament than others. Some have to really work hard to become good, and others never will. This is why the best offhand shots in the old days were held in such high esteem.
PETE