I have one and love it, it flys great.
It didn't at first until I fixed it.
The ejection gases leaving the body tube burned small holes in the parachute tubes and let the ejection gas vent versus pushing out the parachute.
I cut a couple of small slots of either side of the burn hole and inserted a piece of metal flashing which is glued and taped in place. Now it works like a charm.
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It is also important how you load the parachutes, lines first, apex last, like this.
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Minimal wadding and very small pieces.
Good luck!!