This may sound odd to some. I did a trigger job and scoped a Daisy Red Ryder BB gun just to practice off-hand shooting and trigger squeeze. I shoot inside my garage at about 25 feet, five shoots every day. I was amazed how bad an off-hand shot I was a couple of years ago when I started. And how much my groups have shrunk now. While hunting in Texas I took a really nice Whitetail buck from the off-hand position. It was a rather quick shot in some thick brush. I'm convinced that had I not had that garage practice I would not have been successful. I had gotten away from shooting off-hand and used everything in the book for a rest. I think this little BB gun practice has really helped.
