Update on the Diana piston (would like some input )

[bozzer]

Okay ... a few more thoughts ...

Woodruff keys ... Just can't see it. As Rob says it will be a far too complicated job trying to machine slots for the woodruff keys to sit in. That compared to a drill/mill through head and tap a pin in ... It's the pin option every time.

Do they just not bother with the pins and rely on heavy pressure fit of the splines. I can't see that either. There are many reports on the USA sites of wobbly rods. Wobbly rods means those splines have become loose. So the pressure fitting on the splines holding the rods in theory doesn't hold water. Wobble equals loose splines equals rods coming out. The reports are of loads of wobbly rods, but most continue to work indefinitely with no issues. So that must mean despite the loose splines there is a pin in there.

So either the odd one ( rare ) hasn't had a pin fitted and the splines loosen and the rod comes out ... or the odd one has the pins failing. Re the pins failing I'll go with Rob's repeated slamming of piston head maybe causing a fail.

... and yes ... the old rifle with the piston head screw fail is a different story.

Me and Rob should get a room.

PS ... Maybe more than one pin ( both sides ) to prevent off central pressure and a safety measure if one pins fails. So that would mean all pins fail for rod to come out. Maybe if one goes first then the other follows soon after.