! Caliber !! Compatible magazines !! Corresponding base models
|-
| '''[[5.56x45mm NATO]]''' || [[STANAG magazines]] || [[Colt AR-15A2 R6550]]<br/>[[Colt M16A1]]<br/>[[Colt M16A2]]<br/>[[Colt M16A4]]<br/>[[Colt M4]]<br/>[[Colt M4A1]]<br/>[[Colt Mark 18 Mod 0]]<br/>[[Colt XM177E2 Commando]]
|-
| '''[[6x45mm]]''' || [[STANAG magazines]] ||
| '''Subcarbine''' || 10.5 inches || Weapon becomes Class 2<br/>Weight -1 tier<br/>Muzzle: Standard devices || [[Colt Mark 18 Mod 0]] || '''800''' || Installs a very short 10.5 inch barrel designed to minimize size and weight as much as possible, at the cost of ballistic performance.
|-
| '''Commando''' || 10 inches || Weapon becomes Class 2<br/>Weight -1 tier<br/>Muzzle: N/A || [[Colt XM177E2 Commando]] || '''800''' || Installs a very short 10 inch barrel topped with a 4 inch moderator device, which features a grenade launcher ring.
|}
! Configuration name !! Fire modes !! Corresponding base models !! Cost ([[File:Parallar symbol.png|10px]]) !! Description
|-
| '''Safe/Semi/Auto''' || Semi/Full, AutoROF 8 || [[Colt M16A1]]<br/>[[Colt M4A1]]<br/>[[Colt Mark 18 Mod 0]]<br/>[[Colt XM177E2 Commando]] || '''400''' || Original select-fire trigger control group, with semi-auto and full-auto, no burst mode.
|-
| '''Safe/Semi/Burst''' || Semi/Burst3 || [[Colt M16A2]]<br/>[[Colt M16A4]]<br/>[[Colt M4]] || '''400''' || M16A2 style trigger control group, featuring semi-auto and 3-round burst, no full-auto.
! Configuration name !! Effects !! Corresponding base models !! Cost ([[File:Parallar symbol.png|10px]]) !! Description
|-
| '''Original''' || Underbarrel: M203 mount (if barrel is '''DMR, Rifle, Carbine,''' or '''Commando''')<br/>Underbarrel: None (if barrel is '''Competition''' or '''Subcarbine''') || [[Colt AR-15A2 R6550]]<br/>[[Colt M16A1]]<br/>[[Colt M16A2]]<br/>[[Colt M16A4]]<br/>[[Colt M4]]<br/>[[Colt M4A1]]<br/>[[Colt Mark 18 Mod 0]]<br/>[[Colt XM177E2 Commando]] || '''100''' || Original handguards with no features.
|-
| '''Quad rails''' || Lights: 2x Long interface<br/>Underbarrel: Long interface || || '''600''' || Quad-rail handguards to attach the lights, lasers, and underbarrel accessories of your choice.
| '''Fixed stock''' || '''S''' || None || [[Colt AR-15A2 R6550]]<br/>[[Colt M16A1]]<br/>[[Colt M16A2]]<br/>[[Colt M16A4]] || '''150''' || Fixed nonadjustable stock, in the style of the original M16 rifles.
|-
| '''Retractable stock''' || '''RS''' || None || [[Colt M4]]<br/>[[Colt M4A1]]<br/>[[Colt Mark 18 Mod 0]]<br/>[[Colt XM177E2 Commando]] || '''400''' || M4 style retractable stock.
|-
| '''Folding stock adapter''' || '''FRS''' || None || || '''600''' || Installs a folding stock adapter on the buffer tube, which can accept standard retractable stock pieces, allowing the whole assembly to be both folding and retractable.
! Configuration name !! Effects !! Corresponding base models !! Cost ([[File:Parallar symbol.png|10px]]) !! Description
|-
| '''Old style''' || Optics: N/A || [[Colt AR-15A2 R6550]]<br/>[[Colt M16A1]]<br/>[[Colt M16A2]]<br/>[[Colt XM177E2 Commando]] || '''200''' || Original style upper receiver with non-detachable carrying handle, and no mounting points for optics.
|-
| '''Flat top''' || Optics: NATO-S mount || [[Colt M16A4]]<br/>[[Colt M4]]<br/>[[Colt M4A1]] || '''600''' || Modern upper receiver with a length of NATO-S rail for mounting optics. Comes with a detachable carrying handle with adjustable rear iron sights.