AR-15 16” SPR Upper Build 5.56 (2/5): Installing Dust Cover and Forward Assist #arbuild

Amazon list for tools/supplies mentioned on the channel:
3QMZQX5CVKWR2

Upper build tools (1/2):

Upper build tools (2/2):

There Are 5 Videos for this build:
– AR-15 16” SPR Upper Build 5.56 (1/5): Taking Barrel Measurements and Checking Headspace
– AR-15 16” SPR Upper Build 5.56 (2/5): Installing Dust Cover and Forward Assist
– AR-15 16” SPR Upper Build 5.56 (3/5): Installing Barrel Into BCM Thermofit Upper
– AR-15 16” SPR Upper Build 5.56 (4/5): Torquing The Barrel Nut and Attaching Gas Tube To Gas Block
– AR-15 16” SPR Upper Build 5.56 (5/5): Installing Gas Block, Muzzle Device, and Handguard

Build Steps:
Part 1:
1. When the barrel arrives clean the chamber and bore with 91% Isopropyl alcohol then take measurements for weight, gas port size, gas block journal, and barrel extension
2. If you have a borescope, inspect the barrel and take pics/videos to document the initial state of the barrel. If you do see something like weird coloration, damage on the lands/grooves/crown/etc. still try shooting the barrel. If it doesn’t shoot and you think it’s from a documented defect you can always send the barrel back in to the manufacturer
3. Using a 1.4636” min headspace gauge and 1.4736” field gauge make sure the chamber is within min/max headspace specs by checking if a fully stripped bolt will close/twist on the gauges
4. If multiple stripped uppers are available find the one with the tightest fit on the barrel extension (I prefer thermofits)

Part 2:
5. Once the upper is selected (if needed) install the dust cover and forward assist

Part 3:
6. Clean the barrel nut threads, inside of upper, and barrel extension with some alcohol to remove any oil residue, etc. before installing the barrel into the upper
7. If building an accurized upper that’s not thermofit apply Loctite 620 to barrel extension (optional: apply a little aeroshell to the barrel nut threads to protect them from the loctite)
8. If thermofit, heat upper threads with heat gun on high for about 30-60 seconds then quickly slide the barrel into the upper making sure it fully seats. Wipe any excess loctite from the barrel nut threads and inside upper near barrel extension
9. Allow upper to cool (note the loctite needs 24 hours to cure before shooting)

Part 4:
10. Apply aeroshell 64 assembly grease to the barrel nut threads and shoulder of barrel extension
11. Season the barrel nut threads by tightening close to torque spec and loosening a few times
12. With upper secured internally by the lugs with Midwest Upper Receiver Rod, Magpul Bev Block, etc. season the barrel nut threads by tightening close to torque spec and loosening a few times then torque barrel nut based on handguard manufacturer’s specifications (KAK says 35-55 ft-lbs, I use upper end)
13. Attach gas tube to gas block using Midwest Industries lower receiver block and White Oak gas tube spiral roll pin with a 5/64 punch

Part 5:
14. Attach gas block with cup tip set screws @ 15-20 in-lbs then verify gas port alignment w/ scope. Make witness marks on screw heads. **After function check replace cup tip screws with knurled tip screws and optional threadlocker (Loctite 246 or Rocksett)**
15. With upper secured internally via the lugs, oil the muzzle threads and attach the muzzle device (torque to ~15 ft-lbs). Note if muzzle device will be used as a suppressor mount don’t put any oil and instead add a few drops of Rocksett to the muzzle threads before attaching muzzle device (let cure for 24 hours before use)
16. Attach handguard by following manufacturers specs re: use of threadlockers, oil, etc. on handguard screws and torque specs. Witness mark each screw head (use Vibra-tite VC-3 or Loctite 246, KAK spec: alternatively tighten each screw until you get 45 in-lbs)
17. Insert BCG and charging handle
18. Attach upper to lower and do a full function check

Build list (note re: pricing, some of these parts were purchased during Holiday sales):
– Upper receiver: BCM Demo Upper (# FLAT-TOP-UPPER-M4-DEMO) ($50) (thermofit)
– BCG: Radian Enhanced Nitride BCG (# R0081) ($179)
– Gas tube: Rosco Intermediate Nitrided gas tube (comes with barrel)
– Gas block: Rosco .750” V2 Set Screw Gas Block (# ROS-NGB-002) ($38)
– Barrel: Rosco K9 16” 1:7 Intermediate 5.56 Nitrided 416R Barrel (# K9-16-HY-556-7-I) ($135)
– Handguard (10.5” to 13.75”): KAK 13” Handguard (# MO-441-1010-006) ($110)
– Muzzle device: Cross Machine Tool Tactical Combat Flash Comp (QPQ Stainless) ($79)
Total cost: $591

Barrel inspection notes:
– Weight: 34.6 oz (2.2 lbs)
– Gas system length: Intermediate
– Gas port size: 0.088”
– Gas block journal: 0.7505”
– Barrel Extension: 0.9975”

Headspace gauge check (on fully stripped Radian bolt):
– 1.4636”: closes
– 1.4646”: doesn’t close

#arbuild #precisionshooting #upperreceiver #upperbuild #AR15 #GunMaintenance #RifleCare #FirearmReliability