tip: stretch 2 axles and attach them to the same 2 objects, then set the hinge constant to infinity, the decay is accelerated to cause axle collapse within a few physics steps
huh
you're making it wrong
it's a plate-composite material
you start with 3 identical plates
put an axle from the 2nd to the 1st on their centers
then put an axle from the 3rd to the 2nd on their centers
(if you can't find a valid center, any relative position should work if it's the same relative position in both steps)
if your result starts to vibrate, you made it right
tried using my own bullet design in this, took a bit of modification but it finally worked (at below 20 m/s muzzle velocity, self-contained bullets are near-useless)