Breaking glass, especially automobile glass, is a lot harder than you might think. I’ve seen officers whale away on a driver’s window with an ASP baton and do more damage to their egos than to the glass.
I’ve also seen a teenager break out a car window with nothing more than a piece of an old spark plug. So, what gives?
As with all things in life, there is no single answer. Rather, there are a number of factors which go into how likely you are to break out a window. The type of glass, the curvature of the glass and the tool used are just some of the factors which can spell success or failure when trying to breech glass.
Glass is much harder than you might think. Both the Mohs and Brinell hardness scales show glass as being harder than stainless steel – yes, glass. Tool hardened steel can be harder than glass, but then glass can also be strengthened through tempering, lamination and other processes.
Windshields use a multistep lamination process which affixes two layers of glass to each other with a layer of vinyl sandwiched between them. This creates an extremely tough glass pane to try and penetrate.
If you’ve ever seen a gunshot through a windshield, you probably noticed that the point where the bullet penetrated the glass was damaged; yet, the entire windshield still maintained its integrity. It did not fall apart or send shards of glass flying. Trying to breech a car through the windshield is a nearly impossible task. I don’t recommend trying it in anything other than a controlled training environment.
Tempered glass is typically used in the side and rear windows of modern cars and trucks. The tempering process strengthens the glass up to four times the strength of normal annealed glass. Additionally, curved auto glass tends to be stronger than a flat pane of glass. So, hitting a strengthened car window with a comparatively softer baton may yield dismal results.
The funny thing is that most street criminals know a very easy way to break the windows of a car: Use a spark plug. Typical spark plugs use porcelain as an insulator. A quick whack with a hammer will break the porcelain into small pieces. Those small pieces of porcelain will easily shatter a car window when they are thrown.
Most cops who have been on the street for a while already know about the spark plug trick, but search for “breaking glass spark plug” on YouTube if you want to see a video demonstration of this. It doesn’t take a lot of force, or even a big piece of porcelain, to break a window.
Never fear, there are solutions to the problem of breaking windows beyond brute strength and carrying bits of broken spark plugs in your pocket.
Fortunately, there are a variety of glass breeching tools on the market. The forms and delivery systems are different, but they do share some common traits.
First, all of the glass breeching tools use the idea of applying force to a small point. The nar- rower the point of pressure applied, the more likely the glass will break. Once the glass breaks at the point, the entire pane will spiderweb and fall apart.
The second trait shared among glass breaking tools is the use of harder than glass materials for the contact point. Typically, tactical glass breaking tools will use tungsten carbide tips. These tips are very hard and are durable enough to be used on multiple glass breeches without having to be sharpened or replaced. I have seen some “off brand” products use tips made from stainless steel which is substantially softer than tungsten carbide. These tips may fail, so I urge caution if you con- sider purchasing one.
Let’s take a look at some of the products on the market for law enforcement use.
XS Sight Systems’ Glass Assault Tool (GAT)
The Glass Assault Tool resembles a micro- bayonet which attaches to the flash hider of an AR15/M4 rifle. The GAT is designed to attach quickly and not come loose during extended shoot- ing sessions. Once attached, the muzzle of the rifle is able to easily punch through glass. The advantage the GAT has over many competing products is that an officer can breech glass without ever tak- ing his hands off his weapon.
A new version of the GAT for pistols is designed to fit on a SureFire® X200 and X300 weapon light. This GAT slips over the top of the flashlight’s bezel and will fit in all normal police duty holsters which are designed to work with the SureFire light. To use the pistol version of the GAT, the officer wraps his support hand over the top of the pistol’s slide, capturing the trigger finger against the gun’s frame to prevent a negligent discharge. The officer then presses the tip of the GAT into the window, causing it to shatter. According to XS Sight Systems, a number of law enforcement agencies have been testing the weapon light GAT on their pistols and the reports from the field have been outstanding.
The GAT has an MSRP of $80.
Bust a Cap
Bust a Cap has a line of window breaking caps for expandable batons and flashlights. The caps replace the original tail caps with a cone shaped device which comes to a point made of a specialty steel. The points are not so sharp as to be painful when you rub against them, nor will they catch on, or tear, uniforms.
Currently, Bust a Cap makes glass breaking tail caps for a range of Steamlight and Maglite flashlights in addition to ASP expandable batons. They do not make tail caps for flashlights or batons which have a button in the tail cap.
Bust a Cap also announced a new glass breaking bezel for SureFire flashlights at the 2012 SHOT Show. The new bezel is a simple replacement of the stock bezels on the SureFire model 6P, G2, Z2 and C2 flashlights. The new bezel addresses the problem of having the flashlight switch on the tail cap by moving the glass breaking tool to the front of the light. This allows the officer to tap the side window with the front of the flashlight to breech the glass.
Bust a Cap pricing varies depending on which model you need. Pricing for the new SureFire bezels has not yet been announced.
Gerber Hinderer CLSTM
Gerber makes a knife with a built-in window punch called the Hinderer CLS (Combat Life Saver). The CLS is a folding knife with a partially serrated 3.5″ blade.
Unlike some rescue knives with window punches, the Hinderer CLS has a sharpened, not blunted, tip. This makes the Gerber a more appealing knife choice for law enforcement officers.
The MSRP is $80 for the Gerber CLS.
Buck Redpoint Rescue
Buck Knives recently introduced the new Redpoint Rescue knife which has a 2 3/4″ drop point blade and a tempered glass breaker in the rubber coated handle. There is also a specialized seat belt cutting tool built into this knife.
The knife can be had in bright yellow or in black. The Redpoint Rescue has an MSRP of $55.
The Spyderco Assist is a folding knife designed for rescue. The Assist has a blunted tip, serrated blade and a tungsten carbide window punch.
The window punch on the Assist works differently from what is found on many other knives and multitools. Instead of having a tip which is always exposed or spring-loaded, the carbide tip on the Spyderco is recessed.
To deploy the Assist window punch, the officer squeezes the folded knife which pushes the tip out for use. Release your squeeze and the tip retracts.
The Spyderco Assist has an MSRP of $134.95.
Breeching glass, especially automotive glass, can be a difficult chore without the right tools. Using a baton or flashlight can get the job done with the right amount of strength and the right striking point on the window. However, it is not a reliable way to force entry.
In law enforcement, we sometimes only have one chance to get it right. Delays in breeching glass can result in a suspect having time to shoot another officer or an auto accident victim being burned alive. Neither are good outcomes.
Using one of the specialty tools made specifically for breaking glass will dramatically increase our ability to get the job done right on the first attempt.
About the Author: Richard Johnson is a police officer and trainer with a mid-sized police department in Central Florida. He operates the police training web site, BlueSheepdog (www. bluesheepdog.com).
This article is a contribution from articles and gear reviews for the patrol officer. P&SN is a valued supporter of BlueSheepdog and the Blue Crew. You can obtain a free subscription to the Police & Security News magazine by joining the Blue Crew.