You're welcome, glad to help out -and- thanks for thanking.
From the little bit of experience I have shooting snake shot - you have to get really close for that #12 shot to have any effect. Two years ago, I had to shoot a Copperhead that refused to stay away from the front porch - I used a snubby .38 SPL with a CCI shot shell - from approx. 6' - it cut the snake in half about 3" down from the head. I've shot .22 snake shot from a 16" barrel carbine - just to see what the pattern looked like - at about 6' it was pretty dense and about a foot in diameter - anything beyond that it spread pretty wide with lots of void in the pattern. Your mileage may vary, but as you said - practice may be a better solution.
If you e-mail your pics to me I'll post them for you. Just give me a hint what the pics are for - memory sucks anymore.