11.5 Upper A4 1/7 QPQ Barrel
We started with a 11.5" 1/7 twist barrel for this build. The barrel is made from 4150 machine gun steel with QPQ nitride treatment to the exterior, bore, and chamber. The upper receiver is T marked and is type 3 hard coat black. This does have M4 ramps. The Flash hider is our XM177 pinned to meet 16" OAL. Our barrels are Mil-Spec or better. We recommend a 55gr or 62gr bullet for best accuracy. The front sight is a A2 F-Marked with bayonet lug and attached with taper pins.
Upper: 7075-T6 Type 3 Black hard coat Cardinal Forged, Anchor Harvey, Performance Forge upper with M4 ramps
Barrel: M4 4150 1/7 5.56 NATO QPQ Barrel
Gas System: Carbine
Gas Block: F-Marked A2
Handguard: Two Piece Drop In Handguards
Flash Hider: XM-177 Pinned and welded to 16"
Charging Handle: Optional
2 Reviews Hide Reviews Show Reviews
A follow up with the upper. I’ve switched the barrel to an A2 upper. Really like it. Using 62 grain bullets is not as tightly grouped as 64, but very close. Still, no FTF or FTE any brass. Been shooting the upper out to 100 yards and even with 55 grain and up to 77 grain bullets, I can continuously hit a 10x22 target all day. Open sights and red dot have been used with this barrel. Will be taking it to a two day Combat Rifle course shortly to see how it really handles.
The upper & BCG are great. Using a detachable carrying handle for a rear sight right now. No feeding or ejection issues so far. About 300 rounds down range as of this week. It is ammo picky though. I zeroed with 55 grain bullets & the grouping was so-so. Back at 100 yards I switched to 64 and 77 grain bullets. The groups immediately tightened. Not sure which is better because I only had a few 64 grain bullets. This upper has been a lot of fun so far.