eHobby Asia has made a custom M4 gas blowback rifle based on the Western Arms GBB kitted with Magpul PTS part. You can get this for US$900, though it does not come with extra magazines. But still an interesting project to see, which you may want to do it on your own if you have a copy of the Magpul Carbine DVD which will help you how... "We have seen how effective Chris Costa, Magpul Dynamics Instructor, style is from MAGPUL Carbine DVD. Let's follow what he equipped too.

WA M4A1 Carbine GBB Features:

• Western Arms 'MAGNA' Blow Back System offer same recoil as pistol
• Functional Metal Bolt Carrier
• Rigidity Glass Fiber Reinforced Polymer Receiver with Laser Marking
• Die-Casting Metal Processing & Realistic Field Stripping
• Aluminum Made real size buffer tube
• Aluminum Made 20mm RIS Rail

Custom Works:

• MAGPUL PTS ACS Carbine Stock (MAGPUL-056) - featuring Friction Locking Function & Sloping cheek weld
• MAGPUL PTS Pistol Grip with heat sink end cap (MAGPUL-032) - Improved Ergonomics and Non-Slip Rough Texture on both sides and rear backstrap
• MAGPUL PTS MOE™ Polymer Trigger Guard (MAGPUL-052) - Shallow V Shape best use of gloves
• MAGPUL Full Length XT Rail Panel (MAGPUL-009) - Prevent damage on you & your gear from sharp edges
• MAGPUL AFG™ Angled Fore-Grip (MAGPUL-073) - rail-mounted forward grip/index point designed to improve weapon ergonomics and increase shooter speed and efficiency
• Magpul PTS Back-Up Rear Sight (MBUS) - Spring Loaded Flip-Up system, release lever can be reached on left, right & top position
• T-1 Micro Red Dot Sight w/ QD High Mount
• VFC AN/PEQ15 Aiming Module (VFC-ACC-PEQ15) - High precision Red Dot Laser integrated with 130 lumens LED Flashlight"