The M2016 Constitution is a fun but sometimes underwhelming weapon to use. It is outperformed by most other rifles like the Justice when fully upgraded and the M2016 Constitution feels like it has a lot of untapped potential with potential upgrades without sacrificing the weapons character and niche role.
Here are 3 modifications that I recommend adding to the weapons tree to make it more effective in combat.
Bandolier - Facilitates easier access to ammo, allowing for faster uninterrupted weapon reloads. (The rifle reloads faster and continously with one press until full or interrupted)
Bored Rifle Barrel - Adjustments to the M2016 Constitutions rifle barrel allows for larger caliber ammunition to be used, increasing the rifles lethality and round penetration. (The rifle deals more damage and rounds penetrate higher armoured targets more effectively).
Stun Rounds (available after Bored Rifle Barrel) - The M2016 Constitutions bored rifle barrel allows for the use of the latest adaptation of stun rounds, now compatible with larger caliber rifle rounds. (Each shot now stuns any enemy it hits, temporarily slowing their movement).
These 3 upgrades should make The M2016 Constitution more viable in higher difficulty missions when dealing with larger groups or more difficult to kill enemies, whilst also retaining The M2016 Constitutions main characteristics such as being a bolt action, 5 round magazine rifle which must be reloaded one round at a time. They also thematically fit the style of the weapon, owing to the weapons more historical nature.