In my opinion, the very best option for improving your free hand shooting with your double, or any other rifle, is to buy a 22lr with sights close to express sights. I have a winchester lever action 94-22 that has sights close enough for the prupose. Shoot 100 round of 22 at a range session and finish up with ten or twenty 470's or more if your in the mood. Less pounding, less expense, more practice.

You could shoot more 22 but ussually after about 100 rounds a session, my concentration is waivering and so I stop. Some days I shoot more, a few I shoot less.

Frequency of practice makes a difference for me, and if I can keep it to at least once a week for a couple of months before a trip it seems to work best.

I would start at 25yds and work to 50 after "warming up."

Using this technique, my off hand open sight shooting improved considerably.

Edited to add that after a month or so of this practice regime, I needed to shoot only at 50 yds to see if I was shooting well or not since 25yds was too close.

Also, if you work so that you're shooting a light and barrel light 22 well off hand, switching to a heavier and barrel weighted big double that is really easier to shoot is a relief and your ten or twenty or so rounds with your double should be your best of the day.

BTW, I find the "Shoot and See" targets best for the 22's since you can see the group develop. I like the one with multiple 2" os so bulls so that I could shoot 50 or so rounds without having to switch targets. I shot about 15 or so, whatever the 22 mag holds, at each bull, trying to obliterate it. You sure can see when you've pulled one since it stands out in neon.

Good luck,

JPK