The items in-game stats display on weapons and gear is mostly correct, save for a few of the more recently (after 2017) added items.
There are some items that have stats or functionality that are simply not disclosed in any way at all in-game.
SOME Examples of this are:
Snowstrike Rabbit: Sprint Speed Bonus Stat, Additional AP Stat,
Reindeer Holdout Vest: Sprint Speed Bonus Stat, Melee Damage Protection Stat
Eclipse God Ra Armor: Incorrect Speed Stat, Explosive Protection Stat
God Seth Vest: Explosive Protection Stat
(Many) Characters: Incorrect Protection Stat
Holy Range (Tier 1 ONLY) Bullet: Gives ANY GUN INFINITE RANGE (AGAINST PLAYERS NOT JUST NPC)
All-Star Weapons: These all have "hidden abilities", some are functional, some are not.
ICATS AR: Bugged Firerate
Skullshot Raider Mask: has entirely wrong stat listings, gives bullet protection to torso
Wasteland Goggles: Same as above
This list is NOT the full list of incorrect items. I know there are many more items with similar incorrect stat listings.
I believe for the players to have the best experience with Combat Arms it is only right for ALL stats to be ACCURATELY listed in-game.