I don’t mean to shoot down @sectoid_br 's suggestion, but I think it’s just an unnecessarily roundabout way of removing the accuracy penalty from HA in the understanding that it is unfair 
And perhaps it should be removed, I don’t know.
First, let’s assume that the current base range of the Heavy Weapons is alright where it is, somewhere between the range at which one would use the ARs and the SGs. So when using Deceptor in assault armor with accuracy bonus/malus of 0 and we can expect the vast majority of projectiles will hit a target somewhere, that’s where we want it to be (which is somewhere between 5-10 tiles).
Second, let’s consider what kind of disadvantages HA merits for its advantages. For example, comparing NJ HA with NJ Assault Armor
http://phoenix.server317.com/Body_Armor
So…
Armor: 40 vs 24, +16. This translates to immunity vs Shotguns (except Harrower), fire, Redeemer, poison worms, and very high survivability against explosives.
Speed: - 2 vs 0. This is just 2 tiles less per turn. When we look at NJ AA vs Anu AA, or Anu AA vs Synedrion AA it looks like the devs don’t put a lot of value in that: 4 armor is worth 2 speed and 10% stealth, and 1 speed is worth just 2% accuracy. Tbh, on first sight this seems off, as one would expect Speed to be more valuable than that.
Stealth: - 20% vs - 10%. This means that full kit HA can be spotted across the map in daytime. This is a significant disadvantage, but one I think everyone can accept as very reasonable.
Accuracy: - 10% vs 0%…
If we go by the SPD to armor to Accuracy trade offs we see in other armors, it would be that of the 16 extra points in armor, 4 are covered by the - 2 SPD penalty, but the remaining 12 would be covered by the accuracy and stealth penalties.
Now, this just doesn’t look right even by the metrics of 2% accuracy = 1 Speed = 2 armor. It should be - 6% accuracy, even without taking into account the - 10% stealth.
And you can see the same pattern with Helmet and Leg Armor - the numbers are kinda off. For example, HA helmet gets vs AA helmet - 10% accuracy - 5% Stealth and - 7 Perception for just + 10 pts of armor. And so is legs too (a difference of - 2 speed, - 10% Stealth and -10% accuracy for 13 pts of armor).
My conclusion? The penalty to accuracy with full kit can be safely reduced from 30% to 10%. With something like -3/-4/-3, instead of the current -10/-10/-10