I have done my experiments with them. They did fine with small diameter fixed blade broadheads below 100 grains. My arrows started going squirrely with 100 grainers and things went downhill from there.

I had to try a Magnus II at 155 grains, just for grins. It shoots fine on an identical arrow with 5" feather fletch. It dang near hit the target sideways with the Blazers.

This was shooting fingers though, at around 240 fps. They might give somewhat better results for a release shooter at faster speed, but still... I would not use a big honkin' unvented fixed blade head with them.[:-]