2014 STS Arms, LLC., all rights reserved.
Improved MOE rifle:

STS Arms, LLC ST4 Improved MOE rifle has the following specifications:

Barrel: 1x8 twist, 4150 steel, salt bath nitride (Melonite), 16 mid length gas system advanced contour barrel
Front Sight: A2 FSB, F marked, optional YHM flip front sight base gas block ($95 extra)
Muzzle device:  Primary Weapons Systems FSC556 brake or Triad flash hider
Caliber: 5.56mm NATO or .223 Wylde
Bolt Carrier Group: M16 carrier, chrome lined, HP/MPI bolt, Microslick coated, improved chrome silicon extractor spring (red)
Upper and lower receivers: 7075 forged aluminum, A4 flat top upper, mil-spec dimensions, Microslick coated interior
Trigger guard: Magpul MOE
Rear sight: Mapgul MBUS flip up, dual aperature
Charging handle: 7075 forged aluminum, tactical latch, Microslick coated
Buffer: Microslick coated Enidine AR-restor hydraulic buffer, red Cerakote coated action spring
Grip: Magpul MOE
Stock: Magpul MOE
Hand guards: Magpul MOE
Magazine: Magpul Pmag 30rd standard capacity (California model with 10rd aluminum).
Improved Basic Rifle:

STS Arms, LLC ST4 Improved Basic Rifle has the following specifications:

Barrel:  1x8 twist, 4150 steel, salt bath nitride (Melonite), 16 mid-length gas system advanced contour barrel,
Front Sight:  A2 FSB, F marked, optional YHM flip front sight base gas block ($95 extra)
Muzzle device: A2 mil-spec flash hider
Caliber: 5.56mm NATO or .223 Wylde
Bolt Carrier Group: M16 carrier, chrome lined, HP/MPI bolt, Microslick coated
Upper and lower receivers: 7075 forged aluminum, A4 flat top upper, mil-spec dimensions, Microslick coated interior
Trigger guard: Magpul MOE
Rear sight: none
Charging handle: 7075 forged aluminum, tactical latch, Microslick coated
Buffer: Microslick coated carbine weight, red Cerakote coated action spring
Grip: A2 mil-spec
Stock: Basic M4, five position
Hand guards: Standard with heat sheild
Magazine: 30rd standard capacity mil-spec aluminum with Magpul gen 3 follower (California model with 10 rd).
Notes:
STS Arms, LLC ST4 Improved Basic and MOE Rifle replaces the standard M4 contour barrel with a mid-length gas system advanced contour barrel with a salt bath nitride finish.  This change boasts many improvements over the mil-spec configuration:

-- The first improvement is an extra two inches of gas tube slows down the normal violence of the mil-spec carbine action cycle.  It recoils softer and more reliably, as a result.

-- The second improvement is an improved sight radius.  Because the gas system is integral with the sight base and now two inches closer to the muzzle, it moves the front sight further from shooter's eye.  This helps aid in better sighting and more accurate shooting.

-- The third improvement is the contour.  The old M4 contour was designed to be backwards compatible with the M203 grenade launcher system.  As most civilians are not going to be using this item, there is no reason to have both the carbine gas system, nor the funny cuts in the barrel to accommodate the launcher mount.  Instead, STS chose a barrel with a thicker contour under the hand guards and a lighter one in front.  This results in a rigid barrel which remains lighter at the muzzle end (for shooter comfort) and resists flex during rapid fire strings better than the mil-spec M4 contour.

-- The fourth improvement is salt bath nitride treatment of the barrel.  More commonly known as Melonite, this treatment hardens the surface of the steel to a Rockwell hardness of RC70 to a thickness of about 0.005" (compared to chrome lining at 0.0003" - 0.0005").  This results in extreme corrosion resistance, wear resistance, and increased natural lubricity wihtout loss of accuracy.

-- The fifth improvement is the 1x8 twist air gauged match grade barrel.  1x8 twist stabilizes 50 grain to 77 grain projectiles whereas 1x9 and 1x7 both have limits in bullet weights at either end of this spectrum.  Salt bath nitriding will not affect the inherent accuracy of the match bore, wheras chrome lining widely known to adversely accuracy.
Note:  Rifle in Flat Dark Earth and furniture/accents in Foliage Green.
Note:  Rifle shown in Burnt Bronze with Graphite Black accents.
MSRP:  $1499
MSRP:  $1749