Thread: Stability for subsonic projectiles

Gents, can someone pls confirm the following:

Is stability factor the thing that causes subsonic projectiles to keyhole or tumble ? I guess the question is if the stability factor applies in the same way at subsonic speeds as for high velocity ?

I've been playing with the JBM stability calc (keeping velocity constant at 1050fps), and it seems that:

for a given projectile length, the heavier the projectile, the more stable it is
for a given projectile weight, the longer it is the less stable it is

If you use a projectile that according to the calc should be ok, what other factors can cause it to tumble ?