Have you ever shot a gun, or even a crossbow, with a laser sight in real life?
Is there any real "aim" to it? Or are you just looking for a red dot?
I would think that "red dot" would override any aiming you did. It does the aiming for you.
Then, someone with no training can shoot it.
So, should a laser sight give you a +6 or a +10 to your Gun Combat task roll?
I have used a M68 Close Combat Optic "Red Dot" sight on the M4 Carbine in a lovely little garden spot in 2003, 2004, 2005. The AN/PAQ is a combination visible laser, IR laser, and IR flashlight or torch for the Brits. The squad leader had one to designate targets. The squad leader would use the pressure switch taped to the forward stock and shine the laser onto a target the whole squad is going to fire upon such as an enemy machinegun. The visible laser is a nice deterrent to civilians to stop or stay out of an area. Shine a laser on one and they know a rifle is aimed at them personally and this is not confusing.
The Advanced Combat Optical Gunsight (ACOG) is different, though similar in principal. This also boresighted to the rifle and then adjusted to the shooter. This has a red circle or triangle you center mass on your target. Additionally, this has stadia lines and can be used for determining range and using the scope with holds for greater distance. Considered a medium range optic. This requires classroom instruction and a regular range time to be proficient.
The firer absolutely must aim properly with the M68 or the ACOG. This is a sight that is aligned with the barrel using a bore sight. The firer is looking through their own iron sights. The firer has to hold their rifle properly and aim through the sights.
The laser is just a laser pointer. Aligned with the bore with a boresight. The firer could point the laser at something and if the laser is on it, then that is where the bullet is going to go. This would be close range unless your shooting at something pretty large like a city bus or a locomotive.
So what bonuses would I give for these?
M68, +1 at point blank and short range. One action to aim.
ACOG, +1 at point blank, short, and medium. One action to aim. Requires Gun Combat - 0
Laser, +2 at point blank, +1 at short. +2 to a intimidation roll. One action to aim. For the untrained, I would reduce the -3 modifier to -1 for point blank.
Things change rapidly and I have been out now for 20 years.