My first couple of tries I didn't hit anywhere near and all my throws were random but I figured out how to keep my throws consistent
This takes a little practice, like a couple of throws but you will understand it.
First off, you want to swing your hand til the point ur meter turns green then you press R2 (or release the horseshoe)
Secondly, you want to aim the horseshoe. This is where I had difficulty. However, what you want to do is look at the edge of the screen for the boxes. See the boxes? You have one on each side when you play. Remember the position of the box and how it positions to the edge of your television and throw the horseshoe. It's important to remember that position of the box to the edge of your television screen. If you got your horseshoe close (meaning it's on the right angle) then that's the position you want that box position to be there always when you throw it. If it wasn't close, adjust your aim, remember how the boxes line up with your screen and throw it again until you can throw it on a good line to the pin.
Sorry if that sounds confusing but thats my technique and I nearly always win now in horseshoes and got the hand grenade achievement.