The most thorough, and easiest, method I've found to make tallow is to put all the fat into a soup pot. Cover the fat well with water.
Boil it for a bit, so the grease (liquified tallow) rises to the surface.
Now, place the pot outdoors or in a fridge or freezer. When chilled, you'll have a big cookie of tallow on top. Often, you can push down on one side and remove the whole cookie. If not, and it breaks into chunks, remove the chunks.
Wipe the underside of the hardened tallow with paper towels, to remove any water or contaminants.
Discard what's left in the pot.
You can also put pieces of fat in a large skillet and melt the tallow out of the fat, but you won't recover all of it. However, if you have a small mountain of fat to render, you won't care.
Frankly, when you consider how little tallow or lubricant is needed for lubricating bullets or felt wads, you'll realize that you don't need more than a pint.
The ratios I gave for Gatofeo's No. 1 Lubricant ingredients (200/200/100 grams) result in a quart Mason jar about 3/4 full. This much serves me for years.