These targets have been tested with high velocity .22 rounds and .17HMR. At 50m with .22 HV there is little to no damage other than paint removal. With the .17HMR at 100m it was the same. When we reduced these ranges marks started to appear in the steel.
The spinners are laser cut from 6mm steel plate. They have a counter balance to reduce the stress exerted on the frame and bar and improve the amount the target spins. There is a single disk per spinner, below the pivot point so rounds will always be deflected safely downwards to the ground. They actually strike the ground approx 1.5m behind the target. Each spinner has an angle built into it so that should it not move, and cause a ricochet, for whatever reason it will still send the round towards the ground and not directly back at the shooter or spectators.
The stand is made from 3mm angle iron, it flat packs for easy transport and storage and is held together via a piece of M10 studding and wing nuts. Again to aid assembly and quick breakdown.