This is the paper got me started.
ht tp://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.10.1088&rep=rep1&type=pdf
Yes, from a frying pan. But I won't use it to cook breakfast any longer.
Paper targets can be boring, and need a good ($$$) spotting scope over 50 yards.
Metal spinners are the best at longer range, however, too small for pistols (well at least for me...) and not as safe i guess.
My .22lr won't spin up those duraseal targets, the bullets just pass right through, no fun.
So I built this hoping to give reaction like hitting the metals and will last a good weekend of shooting. I will report back after the range day!
edit:
It works great, a brick of 22 hollow pts and a few mag of .45 and it still standing.