Unfortunatly, there are many jobs that require a person to expose themselves to dangerous situations involving firearms. Many also live in neighborhoods in which ''drive-bys'' are a common thing and where many innocent bystanders that get injured or killed every year because of this phenomenon. Here is a breif overview on ballistic vests and what type of protection they offer, based on what Level type they are rated for. This information is intended for law abiding citizens and would-be police officers and security guards who wish to learn a little more on what type of protection is available.
As anyone with any experience with body armour knows, there is no such thing as a 100% Bullet Proof Vest. However there are vests capable of providing a strong protection against common firearm projectiles, giving much more chance of surviving an attack. A significant advantage to anyone who might find themselves in harms way. There are many standards in Ballistic Vest Protection that differ from region to region, with the US National Institure of Jutice's ballistic standards being the most widely accepted. We're going to look at each level of performance, as well as what type of job or duty these are made for.
Type I - Very light weight and usually not accepted as sufficient protection for any law enforcment officer. Better used for protection againt paintball and air rifle shots. Tested to protect against .22LR and .380 ACP ammunition.
Type IIA - The minimum protection for anyone looking for effective protection against most common bullets on the streets. Also the easiest to conceil, because of it's thiness. Tested to protect against 40 S&W, 9mm, 45 ACP, as well as Type I threats.
Type II - A good balance between protection and conceilability. Tested to protect against high velocity 9mm and 357 Magnum bullets as well as Type I and Type IIA threats.
Type IIIA - The highest rating of ballistic protection in soft body armor. Tested for protection against 357 SIG and .44 Magnum bullets as well as Type I, Type IIA and Type II threat levels.
Type III - Hard armor or plate inserts. Heavy and bulky, these vests are made for soldiers expecting armed conflict. Protection against rifle cartiges, tested to protect against 7.62 x 51 NATO bullets as well as Type I, IIA, II and IIIA threats.
Type IV - The highest rating for body armor. Made to protect individuals from Armor Peircing bullets and tested to protect against 30-06 Springfield with armor piercing jacket. Also provides protection for all other types (I to III) of threats.
For More detailed information on the National Institute of Justice's standards, check out the Ballistic Resistance of Body Armor NIJ Standard - 0101.06 PDF file.