大牛们给讲讲挑AR UPPER时主要看什么?

AUV

最近跟风进了这个AIM 18" UPPER+BCG+CH, 不过还是不太懂挑UPPER时主要看哪些东西, 比如和下面那个16"的比较, 除了管长了两寸, 是不锈钢的, 贵了一百块, 还有哪些优势或区别?

http://www.aimsurplus.com/product.aspx?item=XAIM18SSKEYMOD

AIM 18" SS Midlength KEYMOD .223/5.56 URG $599.99

ICE Arms 18 inch 416 Stainless Steel Barrel. Guaranteed quality and accuracy.
Barrel Specs:
• 416R Steel with 1:7 twist
• Chambered 5.56 NATO
• .750 at the gas block
• Mid-Length Gas Shoulder
• 1.95 lbs with pinned Low Profile Gas Block

This Upper Receiver Group is built using a Forged M4 Flat Top Upper Receiver. Machined from a 7075 T6 forging. This high quality multi. caliber receiver that features a Mil. Spec. type III hardcoat anodized finish and M4 feed ramps.

Machined from 8620 Tool Steel (Carrier) and 158 Carpenter Steel (Bolt) Shrouded firing pin. HPT/MPI Tested Black Phosphate coated Bolt inside a Nickel Boron Coated Bolt Carrier and Gas Key. Properly staked Forged Mil-Spec gas key. Bolt is shot Peened and HPT/MPI. Tool Steel Extractor.

http://www.aimsurplus.com/product.aspx?item=XSOTUSTDML16FSB

Special Ops Tactical 16" Midlength .223/5.56 Upper Receiver Group $499.99
• 4150 CMV B11595E Mil. Spec. Rated Steel 16" Barrel
• Mil. Spec. 1/7 Twist Rte
• M4 Barrel Extension with Extended Ramps
• Shot Peened Bolt
• AR15 Bolt Carrier Group with Properly Side Staked Gas Key
• Carrier and Key 5.3.1.2 Mil-Std-171 Exterior with 1.2.2.2 Mil-Std-171 Inner
• Carpenter 158 Bolt /  8620 Tool Steel Carrier
• Black Extractor Insert
• A4 Receiver with Mil-Spec Picatinny Rail and M4 Feed Ramps
• Precision Machined Tolerances to Mil-Spec
• 5.56mm NATO Chamber Properly Headspaced
• Taper Pinned Mil-Spec F-Marked Front Sight Base
• 304 Stainless Steel Gas Tube
• 5.3.1.2 Mil-Std-171 Phosphate Barrel and Under Front Sight BAse
• Goverment Profile Barrel

AUV

can168 发表于 2013-9-13 06:08
贵了一百抉……

哦, 对, 这也是最明显的区别之一, 加上了. 呵呵.