AR-15 inspection

[MegademiC]

This thread is to create a checklist for ar15 users to inspect thier rifles.

This is a list of stuff I’ve learned to look for. This applies to both new rifles and during maintenance.
Im creating this thread to share what I know, and hoping people share other items/points of inspection to help newer members, and those new to the “platform” learn what to look for so they can repair/replace before experiencing a malfunction. Pointers from experts (which I am not) like IG, are needed to ensure we cover everything. On a new gun, this should be after initial clean/lubricating and a few hundred rounds/initial break-in, as brand new guns may be tight in some areas.

I run through this every couple thousand rounds (once or twice a year at current pace) during deep cleaning. I just wipe/relube in between. I hope this is useful for some people as an easy checklist, and Im open to critiquing/additions. I’ll update the OP as necessary to keep it a current refernece.


1. Ensure muzzle device is not loose, if a brake, ensure no baffle hits.
2. Check that gas block and fas tube are tight.
3. Check hanguard/barrel nut are tight.
4. Check optic/sights for tightness. Check witness marks.
5. Inspect gas key for tightess/stake marks have not moved
6. Make sure extractor is stiff, but moves, and has sharp edge.
7. Make sure ejector is stiff, but is smooth
8. Gas ring check: bolt movement should be smooth, but not fall out of carrier when inverted.
9. Inspect bolt lugs for cracks, especially at the back where the lugs meet the body
10. Measure action spring to ensure within relevant spec (rifle/carbine/A5)
11. Check buffer condition, roll pin holding platic end should be flush on both sides
12. Funtion check lower fcg. Dont let hammer hit mag catch. Dry fire, check that disconnector catches hammer.
13. Disconnector should be smooth, but positive.
14. Fcg pins should be flush on both sides
15. Mag catch should be smooth, but positive (not as forceful as other springs, but return instantly when not contacted by hammer.
16. Make sure fcg is clear, no primers or other debris in there.
17.after assembly, action should be smooth, no binding (a dry action spring will cause some roughness/noise, thats ok)
18. Final function check (dry fire, hold trigger and cycle for reset check).
19. Inspect castle nut is tight, staking marks are in-line
20. Ensure pistol grip is tight

[thopkins22]

The extractor should also be felt and looked at. It should be sharp.