At the very least, all non-loadout weapons should descope when shot.
DMR
In this Halo, fast kill-times are a necessity so that players cannot Sprint away so quickly. Therefore, the killtime of this weapon should not change. What should change however, is the real problems at hand: the excessive Red Reticle range that makes the weapon behave as if it had a 4x scope, and large amounts of bullet magnetism and auto-aim.
The new RRR should by 30/90, like the LR and it should be the hardest of the 4 to aim, making it a versatile weapon, but not an unbeatable one.
BR
This weapons should be a 4sk with reduced spread, to keep it from being a lottery cannon. The bullet magnetism should also be reduced as well so that it has more than the DMR, but less than the Carbine, so that it won’t be too easy to use for it’s power.
Carbine
Even if returned to it’s status at the E3 beta, it will still hardly be better than the BR, despite it being harder to use. Therefore, it should be buffed in other ways. It’s spread should be totally removed, and it should become more effective at slowing down sprinting players. Hell, perhaps even experiment with a stun/slowdown effect of the Plasma Rifle in Halo 1. It should have less bullet magnetism than now, but still the most of the precision weapons
LR
This gun is almost perfect, except it should shoot a little faster unscoped to keep up with the others, and it’s aim assist should be equal to the BR.
Automatics
These weapons all need to be harder to aim, but should be more accurate in response, allowing better players to utilize them and to bring them out of simply being noob weapons.
The AR’s bloom should expand slower and contract faster, heavily rewarding burst fire and making it a rifle, not an SMG. For Halo 5, I think it might be interesting to shrink the reticle, and give it a scope, where the reticle will be even smaller. The gun should also receive headshot bonus damage when scoped. Just a thought.
The Storm Rifle needs faster traveling projectiles, slightly less bloom expansion, and should be able to squeeze out a couple more shots before overheating.
The Suppressor should still be a 2-handed SMG, but it definitely needs more range. It’s projectiles should be sped up and it’s bloom should expand a tad slower.