For those who don't know what I am talking about
http://www.airgunbbs.com/showthread....-(A-bit-scary)



Over on the DWC a member might be cutting a piston in half so we will have more idea what is going on and also one of the owners of a piston that has separated stem seems to be saying that the the groove in the stem is not lined up with the crimp on the piston body, so until we can look at how the stem is held in it seem to be a guess.
Does anyone on here want to have a guess or does anyone actually know how the stem is fixed in the piston head because I don't yet

The few that have failed seem to be recent pistons, just think how many Diana pistons out there (and they are all fixed the same way) in three parts that have not failed.

A close up pic of the piston parts, HOW IS THE STEM HELD IN ?