I like the smoke 40 a day + gargle whisky thing, that's amusing.
But doesn't work for me.
Practice innit!?
I remember making my throat bleed and losing my voice many times while trying to 'growl' along with those DM classics when I was younger.
My balls have dropped now, so it's easier...
ha ha

Do you want ultralow distorted vocals or ultra high pig screams?

Coz when I want low vocals I do with same as when I'm doing Death vocals so it's all from the stomach, but I find i get much lower by being quieter with my voice and not bellowing it out as much. If you want it to distort slightly just put the gain on your PA up as well.

For pig screams I tend to stand straighter so I can get a lot of air in my lungs and scream from my throat and let rip.

If it hurts that's not a good sign, you really need to be careful with your voice. I avoid cold and carbonated drinks, also sugar. Cold drinks course you vocal cords to contract and sugar coats your larynx. Also be careful with cigarette smoke as it can decrease you lung capacity.

But to be fair I dont play in a gind band, I do Death metal!

Sounds like youve hit the nail on the head!

The way i would do it is,

Practice making the gore sound as a whisper exhaling and making different shapes with the inside of your mouth.

Then keep the shapes and try it inwards.

If you have a good gutteral growl on you just apply the same shapes exhaling.
You get more volume.

Interesting posts here, I'm sending this link to my singer.