As of Update 9.5, the Acrid uses a different reload animation than other pistols.
As of Update 10.3, the toxin mixture in the barrel is affected by your energy color, and the tiny explosion effect on needle impact. Note that the explosion effect is purely cosmetic.
As of Update 11.3, the Toxin effect's DoT scales with Acrid's base damage, not including elemental mods. To clarify further, onlyHornet Strike and Magnum Force directly affect the DoT. Damage per tick is 50% of this base damage (a rank 10 Hornet Strike will yield a base damage of 64, with the DoT doing 32 Toxin damage per tick).
Considering its accuracy and effectiveness, sloting a Pistol Ammo Mutation won't be necessary unless you're playing an endless mode.
Whereas perfectly accurate, it's not recommended to slot Magnum Force at all as it will only result in an (paradoxically) inaccurate mess wasting your ammo.
Semi-automatic firing can be countered by simply adding an alternative way of firing on 'scroll up' or 'scroll down' through the key binding customization.
Before Update 10, Saryn + Mire + Torid + Acrid would give you the only loadout consisting solely of toxin.
Alternatively, one can use the Dual Ichors in place of the Mire for more damage. They also deal pure Toxin damage vs. the Physical damage of the Mire.
As of Update 11.4, the Acrid is physically the largest handgun in Warframe.
Acrid will not change its proc damage type in game regardless of mods. (e.g., changing it to viral will still show toxin procs in game). This causes less DoT damage to robotics.
Currently procs every single shot, or a very high percentage.