Back for the second half of the build.
The stripped upper on a bench block preparing to install the forward assist.
Completed upper with the tags for the parts used. The customer is left handed and may run the charging handle from the right side. In that case the use of the FCD Low Drag Forward Assist means less chance of scraped knuckles during a malfunction clearance drill.
A view showing how minimalist this forward assist is.
Before and after of the feed ramps on the Criterion Barrel.
Initial dry fit of the barrel to the receiver. Went back and opened up the right edge of the right ramp. The left ramp was okay. Don’t really want to take the anodizing off the ramps in the receiver as that makes them prone to being damaged.
Prepping the bolt to check headspace. This fixture makes it easy to remove the pin holding in the ejector. The ejector can give a false feel during the headspace check.
Stipped bolt ready to check headspace.
My headspace gauges are on the bottom of the picture. Since this picture I have added a proper 5.56mm headspace gauge. The barrel did pass the .223 Remington GO gauge. It also passed by not closing on the 5.56mm max gauge.
Nicely dimpled by Criterion
SLR Jig to add a second dimple. Why? Because your gas block can’t be too secure.
After the jig.
Cold blued he spot for appearance and corrosion protection.
Used Loctite 620 Bearing Retainer to bed the barrel to the receiver. The bearing retainer will swell slightly, filling any excess space, and lock the the two together improving the rifles consistancy.
Barrel and receiver hand tight. Waiting for the bearing retainer to set up.
Installing the Sionics Mid-Length gas tube.
Just enough of a second dimple for the set screw to dig into.
Original set screw.
The knurled set screw I actually used. In addition to the knurling I also used VC-3 to insure the screws don’t loosen.
Torquing the barrel nut on the Midwest Industries Slim Line Combat Rail to 40 foot-pounds. This is the 15 inch version. I really like that the barrel nut for this line of handguards doesn’t need to be timed to the gas tube.
Torquing gas block set screws to 30 inch-pounds.
Fully assembled gas system.
Testing that the BCG not impeded by the gas tube. It passed with no interference from the gas tube. This will maximize gas tube and gas key life.
Customers choice for a muzzle device.
Hand tight to the crush washer.
Tightened till the marks aligned.
Almost finished. Most of the hard stuff is on.
Even though its probably not needed. I still used the rail alignment fixture to make sure the rails are straight.
Torque tab installed. Keeps the handguard from coming off and prevents over-tightening of the screws.
Setting the torque.
Assembly complete. only a few more parts to add.
Starting top see what the final product will look like.
This is one of the last parts.
First assembly. Hope the customer likes it. Just have to add a few accessories.
Its not loaded. Just waiting on BUIS from Midwest Industries.