Lasers tend to not pass through things. Lasers also require as big of a focusing device as possible.
Today-lasers focus their energy on a single spot to heat it up. It is really more like holding a small blowtorch near your target than firing a bullet. You'd use the weapon to burn their skin/clothing/etc like a flame thrower. This would be your DR Tier 1 laser.
A more-powerful laser is also a terrible weapon for 'bulleting' someone. As more heat is put into one spot on your target, you end up vaporizing the surface and turning it into a dense plasma which helps dissipate and absorb the laser blast. Lasers in this more powerful range tend to pulse, turning on long enough to blast away some material, then turning off to let the plasma dissipate, then turning back on again hundreds of times a second. These things are really slow at cutting through things but they'll take chunks out of people or armor. They might be your DR Tier 2 laser.
A more-more-powerful laser doesn't care about that plasma forming, it just keeps dumping energy into that plasma to make it hotter. Rather than drilling through a target, the point of impact just becomes a rapidly expanding cloud of gas. It would feel like a grenade went off on the point of impact. This is what happens for your Tier 3 onward laser until you hit Tier 15 where you're just firing the deathstar at things.
The Beam of the YAL-1 is also a lot larger than a penny. The car-sized lens at the front generates a car-sized beam which is then focused down to about a penny in size when it reaches the target. Because of how lasers work you need to have as large a lens as possible to be able to focus the beam. For the range of a normal gunfight you'd be looking at a lens maybe 4-5 inches across like an old handheld camera (They focus light for a picture, its literally the same technology that would be used in a laser). These are sci-fi space lasers though so feel free to do whatever. You could always just have a small lens and make up for it by pumping in a lot more juice.