Hard cast lead bullets are definitely the solution when you need extreme penetration on the cheap.
Cast lead bullets do a great job at breaking through many obstacles that ordinary hollow points or even full metal jacket rounds don't often get to break.
Hard cast lead rounds are for those instances when you're shooting a target that is dense. Like a bear, or even a moose. Big game that you know has plenty of tissue to allow maximum penetration without worrying about the round exiting the other side.
I personally have purchased some hard cast lead 10mm rounds for my Glock 20. The lead does not plug or erode the rifling in the pistol barrel because its designed to feature a copper jacket at the base of the cartridge to aid in the prevention of any damage.
The 44magnum cast lead rounds that were used in the video demonstrate the penetrating capabilities that these rounds were originally designed for. While these rounds are definitely not the type you want to sustain a training mission with you can definitely keep a box of these on hand for a good hunting trip or even consider them as a CCW cartridge depending on where you plan on carrying.
It's a great brush cartridge and can definitely penetrate a lot of vegetation easily. Stay safe and keep training to learn how barriers respond to different bullet types so you can prepare yourself for trips or missions ahead.