My suggestion is that you do a spell to warn you in advance before something dangerous happens. You may feel if something bad will happen, and then avoid the situation by following your intuition.
Ask the spirits to protect you from dangerous people. Do protection rituals and wear herbs like mullein or leeks.
I agree with ManEater, try to worry a bit less. If such a thing occured, your adrenaline would kick in, - you would be amazed at what you are capable of in a crucial situation. Also, I'm somewhat amused by the concern of affecting the free will of someone who's pointing a gun at you! That is pushing things a bit far xD
If you have a gun pointed at you, you should be calm and do nothing that will cause the person to shoot. Freaking them out by mumbling an incantation under your breath may just make them shoot. In situations like that, magick should be the last thing on your mind. Honestly, most who point a gun are either more than willing to shoot at the quickest movement (have killed or harmed before with it) or never intend to shoot at all and use it as an object of control. Some "guns" are even just lighters or other object pressed to you to make it "feel like" a gun. But you never know if it is or not, so it's best to always assume it is lethal. You should try to avoid all environments that could cause you to be in such a situation, remaining on busy streets and staying out of alleys.
Defense against burglars can be done with candles/ritual and if your neighborhood is known for them. Preventative magick is quite common. A simple spell I heard of is placing a small knife or letter opener into a cup of water in your home at all times. There are far more intricate ones though that have been created for that purpose throughout the ages. Most times guardians or wards are used in the form of plants/herbs, statues or amulets.
If you want quick protection, look into amulets. I wouldn't bet your life on one, but wearing them tends to ward off accidents and harm to you.
When dealing with a gun-wielding assailant, don't bother with creating a shield. You would basically have to summon a brick wall into existence in front of you to stop a bullet, and that would leave you too tied to do anything else. Deflecting the bullet is possible, but very difficult as it requires a huge amount of accuracy and literally lightning-fast reaction time. The best course of action is to disable the gun. A variety of things can cause a gun to jam, but I think hitting the safety is the simplest solution. However, even this is difficult because of how much concentration it will take. Taking all this into account, use protective and preventative spells and simply avoid these life-or-death situations.
Sorcery is doing a physical act to get a result right?
And a defense against the dark arts techniques is to use a form of martial arts against something like a gun.
So, an emergency spell against a gun or danger like that, is using a martial art to defend yourself.
The best way to predict the future is to create it, and if you don't want to get shot or something like that, then taking physical action is the way to go.
You have to be kidding... Setting the gun on fire, making the gun jam? How long have you been practicing magick? I have only been practicing a few months to know that the thought is moronic! Magick does not affect the physical world so directly like you like to think. So I world do a universe jump spell to jump into the fantastical world of Harry potter where all these ideas seem logical.
