Ball Joint Torquing (Waggy 44)

I am having a problem with the lower ball joint turning in the ball socket while I am trying to torque it. All of the tips I have found show appling pressure with a jack, but they all still have the axle in the vehicle. My axle is still out of the vehicle, and its own weight doesn't apply enough pressure to prevent it from slipping. Will I need to wait until I have the axle in the vehicle so that I have enough weight to properly torque?

is it a brand new ball joint?

if not - replace it...

if it is, try hitting the knuckle into the inner C with a hammer to wedge the taper... could also try an impact with a u-joint on it which should tighten the nut enough to engage the taper and prevent it from spinning...

Use a ball joint press backwards to put pressure on it.

Thanks for the help, using the ball joint press worked great.