AR-15 build

Good afternoon, everyone! I know this is mostly a handgun forum, but I figured I’d document my current build for anyone wanting to put a rifle together. Most probably already know how to build a rifle, but I am grateful for the person who showed me the basics, and the people that are currently helping me improve my build quality. Shout out to @Todd30 and @Craig6 ! I appreciate y’all’s advice. All the steps aren’t necessary for the average build, but this build is purpose specific. All brands can be changed to your preference. Unfortunately, I didn’t think about putting this here until I was done with 90% , so there are no pictures. My bad.
So for this build, my parts list includes:

  1. Aero Precision stripped lower receiver
  2. PSA lower parts kit (minus FCG)
  3. Rise Armament RA-240 trigger
  4. Zero Delta buffer tube, castle nut, buffer spring
  5. B.A.D H2 buffer
  6. Wilson Combat assembled upper receiver
  8. Wilson Combat 20" super sniper fluted barrel
  9. Precision Armament M4-72 brake (with the stupid shims)
  10. Zero Delta 15" handguard
  11. Furniture
  12. Aero Precision gas block
  13. Aero Precision gas tube

Tools needed:
1: vise
2: upper vise block
3. Torque wrench
4. Small punch set
5. small hammer (ball peen)
6. Tape
7. Armorer’s wrench
8. Small flathead screwdriver
9. High temp grease (I used Aeroshell 64)
For extra steps:
10. Shim material
11. Combination Dial caliper
12. Locktight (I used Locktight 609)
13. Small torch
14. Drill press
15. 1000 grit silicone carbide sandpaper
16. Machined stainless steel block
17. Brownells upper receiver facing tool
18. 220 grit silicone carbide abrasive
19. Red Locktight
20. Patience

Lower receiver assembly:

  1. Place left side of magazine catch in lower, slide spring onto mag catch bolt from right side, and thread on button. When button can’t be screwed more, push button toward frame, and spin in flat side from left until bolt is flush with top of button. Use empty mag to check function and adjust if needed.
  2. Tape receiver with painters tape behind bolt catch pin ears, place bolt catch and spring in left side of lower, then use a starter punch to tap in bolt catch roll pin. (If you purchased a lower similar to the Aero M4E1, the pin and receiver are threaded.)
  3. Attach springs to trigger and hammer, place trigger and disconnector in lower and slide in pin. Then insert hammer and pin.
  4. Slide a punch that fits snugly into the pivot pin holes at front top of receiver, put detent spring into detent hole followed by detent. Carefully push in detent with fingernail, and slide punch forward to capture detent. With pressure on punch, line up pivot pin and psh the punch backwards with pin until pin is in first hole. Then rotate pin so detent snaps into pin groove. (Note: if you don’t keep pressure on punch while pushing pin, the detent will separate the two and put itself into orbit.)
  5. Thread castle nut onto buffer tube and slide on endplate. Thread tube into rear of receiver until bottom of tube is to the buffer retainer hole. Insert buffer retainer spring and retainer into hole, push in with punch, and thread in buffer tube until flush with top of receiver. Turn past just so that takedown pin detent hole is clear of plate. Insert takedown pin detent and spring. Push spring down with flathead screwdriver, rotate tube so plate lines up with receiver, push plate forward against screwdriver, remove screwdriver, tighten castle nut, and stake with punch. Insert buffer spring and push in buffer until captured by detent.
  6. Pull hammer back one click, insert safety. Flip receiver onto side with safety detent hole to top, insert detent, put spring in grip, line up and hold grip to receiver, and tighten grip screw. Check function.
    6.5. install adjustable/fixed stock.

The next couple steps are not necessary for builds, but I’m taking as many accuracy variables out of the rifle as possible.
7. Face upper receiver barrel flange
8. Measure upper receiver barrel flange and barrel extension. Use simple math to determine shim thickness. Cut and fit shim. Apply Locktight 609 to barrel extension, apply shim, apply Locktight over shim, and heat upper barrel flange evenly with torch. When upper is ready, slide over shim on barrel extension swiftly to extension shoulder.
8.5. Polish feed ramps

Back to normal assembly.
9. Grease and torque barrel nut to 35 ft/lbs, break lose with something other than your torque wrench, repeat, torque to spec. Or until gas tube ports line up, but do not exceed 80 ft/lbs.
10. Install gas block. If barrel isn’t dimpled, break the taper off the end of a toothpick, insert into gas port on barrel, break off flush, line up gas block eye close, plug one end of barrel, and blow air into barrel rotating block until toothpick slides into gas block. Use cleaning rod to break and remove toothpick. Torque gas block set screws.
9. Insert gas tube into upper receiver, and slide forward into gas block until pin holes align. Tap gas tube pins into gas block.
10. Install muzzle device. Torque to 20 ft/lbs.

Next steps not necessary.
11. Remove bolt from BCG. Remove extractor and ejector. Use drill press machined stainless, and 1000 grit to polish bolt face.
12. With bolt removed insert carrier and tune position of gas tube to slide as smoothly as possible into gas key.
13. Reassemble BCG.

Back to normal assembly.
14. Attach handguard
15. Lube BCG, insert charge handle, insert BCG, and push both forward.
16. Line up pivot pin holes in upper and lower receivers, push pivot pin in. Line up takedown pin holes, push pin in. Check function.
17. Attach sights/optic/etc.
I’m sure I left something off in there, but I can’t always be perfect :man_shrugging:t3:


Headspace check! I have to recommend that you either check or have the headspace checked for your specific barrel/bolt combination before assembly.


You know Levi long guns are not my thing but I appreciate your skills and ability and admire them.


I may have missed if mentioned but a layout with parts list on a sheet of paper is a great reference to make sure you’ve accounted for every part on every build, works great. You can print one out online easy enough. Great listing, well done on detailed post.


It’s not in there, but a shopping list is always a good idea :+1:

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