You may never need a tourniquet, but if you have an arterial bleed, you have the rest of your life to find one. Most people have never seen a man die from an arterial bleed. It is informative far beyond its shock value.
How long do you have before you lose consciousness? The following (Graphic) video shows the result of a single gunshot which severs an artery.
I am not a fan of bank robbers, but a tourniquet and a little first aid knowledge could have saved this guy.
I have read a lot about improvised tourniquets. The fact is that they don’t work well and you have very limited time to stop the bleeding so you better make one fast.
Get some training and a quality tourniquet. There are many options, I like the CAT tourniquet from North American Rescue. You can apply it to yourself with one hand.
You have the rest of your life to get a Tourniquet.