The forks of the Halligan bar get the bulk of the attention in most fire service text books. To meet "critical criteria" on various state or local certification exams you must force doors by a very specific check list of operations using just the fork end with great attention to detail on how the bevel or arch of the forks is in relation to the door jamb. Too many firefighters who receive this style of training for testing will miss out on the true versatility and power of the Halligan bar.
In many situations the forks (especially when well tuned) will get you in as easy as a key. If you look at the fork end of the Halligan in this picture you can see the gradual curve working easily around the door, past the jamb and behind where it will grab for the force. For this reason I like to think of the fork of the Halligan as the finesse end; designed to be used with sound techniques and simple passing of the tool for your common doors. The forks only really come up short when a more fortified door requires more force. If you look at the forks passing around the door here you see that there is no real lever. The force will be created by rocking the back of the forks on the metal jamb behind it. The adze end on the other hand is pure mechanical advantage in several different applications and has greater weight for purposes of failing doors with a strike.
The two videos below are examples of how you can start to fail doors with a strike. A well fortified outward swinging door with a tight gap can be struck with the adze end to collapse the hollow core causing a slight roll at the jamb creating a gap
As mentioned above when talking about the forks, if the tool is well tuned even a door with tight gap can be defeated without striking it in the above manner. The adze end of a Fire Hooks Unlimited Pro Bar has a thin profile and gradual taper. By design this part of the tool will also pass smoothly around the door with very little force. A single firefighter can effectively work the adze and strike the Halligan in tandem. Once the adze is worked past the door the lever design of the adze in relation to the bar multiplies the single firefighter's force and even doors with multiple locks can be forced. Below is a video of a single firefighter defeating an outward swinging door equipped with a key locked panic hardware door (very common commercial set up) in seconds.
Find more videos like this on Fire Engineering Training Community
Sometimes even with the power of the adze you will find that the initial gap and set attempts aren't enough to get you in. On these rare occasions where the locking mechanisms or security features are no longer the weakest link it is time to start taking down the door and create a larger gap so you can get more of the tool and therefore more force behind the door. By using the adze end in your gapping attempt when you hit this point you have the option of applying upward or downward force to the forks which twists the adze in the gap which on a 30" Pro Bar delivers a 15:1 multiplier of your force easily collapsing most doors in a substantial jamb creating a significant gap for you to attack on the second attempt. Some groups have called this method "tunneling in".
Once you have created this larger gap it should be much easier to drive in and set the adze completely behind the door making the back of the bar the fulcrum and allowing for a powerful force nearly 5 to 1.
Some of these videos are recorded on the hinge side of the door, this is not to demonstrate attacking the hinge side. This is because we were using a building under demolition and we had already forced the lock side of these doors. By moving to the hinge side we are able to use the same techniques on the other side, essentially getting two props out of each door. This isn't to say that you should "never" attack the hinge side but it should be the last resort. As my brothers at Irons and Ladders have explained to me, consider each hinge as a lock that you must over come and the fact that once they are forced this is not the way a door is designed to open and you may have to work the lock side as well.
I am sure this is not new information to many of the members of this training community but I hope that some find value in it. The adze end of the Halligan is a force multiplier and with a good understanding of the versatility and power it provides even a single firefighter can overcome some of the most formidable forcible entry challenges.