My first " Oops" was when I was very new to shooting bows and practicing in my backyard with field tips. I took a giant tape measure and measured off 30 foot increments (10 yards at a time) across my lawn, from my metal storage shed, to my backporch stoop. The back fence and wood pile to the first step measured exactly on the dot - 30 yards.
My old PSE Edge 1000C bow has Tru-Glo 3 pin sites (the bow shop " guess-timated" they' d be 20-30-40, when they setup the bow for me). I took my target bag and decided I' d need a huge backstop, because I had no idea what I was getting myself into... I used my metal storage shed as a backstop! You guessed it... You know exactly what happend... I lifted the bow just as soon as I hit the release and sailed the XX75 #2315 arrow about 1 foot above the target bag! [

] The arrow went right through the metal door of the shed, ripped the fletchings almost off, and went in between the spokes of my daughters bicycle, and stopped just short of the rubbermade container which holds the camping gear and tarps and stuff! My wife heard the CLANG noise as the arrow went through the shed. Man, she was hot... She was ready to kick my a** !!! [

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I have since gotten a lot better and practiced and practiced until I can get good groupings and put the arrow in the bullseye from 30 yards on a consistent basis.
Butch