This has been years in the making.  I finally put it on (digital) paper.  This diagram should cover most of the basics.  This covers simple blowback 9mm AR's only, not CMMG Banshee or other mechanically delayed systems.

The latest version can always be found here: https://blowback9.wordpress.com/2021/10/22/9mm-ar-troubleshooting-guide-simple-blowback/

9mm AR Basic Troubleshooting Diagram v.1.1



More information and details can be found at Blowback9.com

I hope you find this helpful and interesting.  Feel free to ask questions.

Well done, Sir!

This  needs to be a prominent sticky at the top of the page.


Nice work OP...many of us on here appreciate the time/effort you put into helping others.



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Between you and Amphibian I've learned so much about 9mm ARs. I appreciate the education gentlemen, you guys are great.

@VA-gunnut

Worthy to add to "Important pistol caliber threads" at top?

Is this applicable for all pistol caliber ARs?

It's designed around all the work and research I've done on blowback 9mm AR's, but the basic principles are the same.

First, this is a great trouble shooting flow chart.  Hopefully it will same a lot of basic questions needing to be asked.  The only change I'd suggest to it as it exists, is your very first box should read "charge gun" instead of "chamber round".  (If the instruction is "chamber round", the answer is always "yes" if you have proceeded.  I'd go with "charge" because that's the action that attempts to chamber round, then the next step evaluates the results of charging.)

Second, I think there might be even more you could add to it, or as a notes with it.

For example, it doesn't contemplate someone attempting to chamber an incorrect caliber round.  If someone shoves a Glock mag of .40 S&W in their small frame Glock lower with a 9mm upper, the round won't chamber and your chart has no check.

I'm a big fan of accounting for that level of idiocy.  Last time at my FFL, I heard workers chatting about S&W's great customer service/warranty, citing how they fixed (free, 2 week turnaround) a woman's gun after she forced the magazine into it backwards and messed it up.  People do unexpected, stupid things.  My general guide is "geared to catch mistakes someone recently concussed might make."

Even if you don't account for the real idiocy in the flow chart, it might be a good idea to lay out a list of presumptions necessary for the flow chart to work so a true noob doesn't miss something we all would just assume they did.

Thanks for the suggestions!   I would try to make it idiot proof, but someone out there just keeps making better idiots. If I go too far down the rabbit hole it'll be 20 pages long, so I just wanted to keep it high level.

Very nice.  This should be helpful for those of us just building a 9