Quick-A
The Quick-A magazine is a attachment unlocked by acquiring kills with the corresponding weapon.
In-Game
The Quick-A magazine attachment decreases the reload time of any weapon it is equipped on. Most weapons see a reload time reduction of approximately ~16.7% or roughly one-sixth. Some do gain a slightly lower or higher reduction, ranging between 16% to 26%. The MK14 EBR sees the least benefit, gaining a 16.1% decrease. The P90 gains the largest benefit, seeing a 25.8% decrease.
The Quick-A attachment also negatively affects some weapon's others statistics, mainly recoil and control.
Data Points across the weapons
Datapoints are set in category for best to worse
ARs
Fal 21.5%
ACR 21.1% (Quick B 13.1%)
M4A1 20.6%
SG550 20.5%
AK74 16.7%
AK15 16.7%
SCAR H 16.7%
AUG A3 16.7%
FAMAS 16.7%
G36c 16.7%
HK419 16.7%
SMGs/Carbines/PDWs
PP19 25.8%
P90 22.9%
UMP45 19.35%
MP7 18.75%
MP5 18.7%
Vector 18%
Honey Badger 16.7%
AS Val 16.7%
DMRs
MK20 20%
MK14 16.1%
LSW
L86A1 16.6%