For p90 there could be a special rule that it aplies onehex damage effect from 3hex instead of 1.
p90 is ineffective in comparison with let's say miniguns with 1hex damage anyway. There's a problem i have noticed in combat when someone is rushing at you with a minigun when you have less action points/injured and can't risk a frontal engagement ( have to stay out of sight ), running is the only option to buy time as i call it. Buying time is the same thing as accumulating enough action points to retialiate, either eating a SS to survive and keep moving or setting up a surprise attack around a corner with well timed 6 action points in the face.
Anyway, let's imagine the guy with the minigun is chasing me at relatively close range and i somehow buy enough time for a burst, i have A option to engage in close combat (bad idea if the opponent has more action points/health, especially if health, your the one with the disadvantage), or i have B option to try shooting him from range( approx. 3-5hex, if he is that close ) and continue moving, something like kiting. Being at such a range the animation is too slow to complete in time for me to resume any other action and in most cases the guy with the minigun catches me in 1hex range while i'm completing the animation( that's where latency really comes into play). I have good latency btw.
Get the problem? I am not sure if those 3 hexes can be utilized effectively against other weapons who do simple 1 hex, the change might not live up to the expectations, because of the game mechanics, let's say i have thought about this.
Range should be 5 at least, i think it wouldn't be so bad since p90 does really bad damage at range.
and if you want to make p90 dominant in close combat, then it's simple, decrease minimal/maximal damage in conjuction with increasing bullets shot per burst and magazine size, so it scales better with BRD.
Cool p90 in my opinion would be 50 rounds in magazine and 25 bullets per burst( with decreased damage per bullet of course ), add this 5 hex range on full burst damage, and you have a beast usable weapon, not as strong as a minigun, but it has utility and can compete at some degree of level - close range. Like SG minigun
Assault rifles could have simply an option to do aimed chestbursts. Perhaps only sa80 could work like this, or we end up having critburst ar trolls, even though ar burst isn't even that powerful.
I see AR as a well balanced weapon, it doesn't excell anywhere, but it's decent at everything, range, does medium damage as well requirements. I don't think it should be changed, we have some buffed XL70/FNFAL that's better than AR anyway, at least should be as higher tier weapons.
Shotgun and knocking down is a must in some way.