Understanding and Correcting AR Issues

[Henryrifle]

I am looking for a thread that would help all of us understand more about AR-15 operation especially when ‘problems’ are encountered.

We’ve all seen the ejection angle chart and perhaps the resolution steps outlined in that chart, AGB, lighter or heavier buffer and/or buffer spring and gas leaks are the only changes you can make. But what if you are willing to address the root cause?

Those ‘fixes’ seem more like a reactive change to compensate for what is actually the problem like putting Radiator Stop Leak in your car’s coolant system to ‘fix’ a leak. Yeah, that sometimes works but for how long and what other problems does that cause in the longer run?

I am sure the information is here in various threads but it would be awesome to consolidate them or links to them in one thread.

Before I ask for contributions, we all understand there are differences in opinions about some of this stuff. That’s okay! I don’t want to be the catalyst for disagreement but rather one for solutions. There is more than one way to skin a cat.

If any of the really knowledgeable folks see value in this please contribute. Just to reiterate, providing bandaid solutions is okay and maybe all you can do but I’d like to understand the actual cause(es) of common and complex issues

Issue Samples (many others, I'm sure):

• Ejection angle pattern
• Bolt unlock timing
• Ejector brass flow
• Extractor swipes
• Heavily dented cases
• What is changed when adding a suppressor

Thank you all,
Hank

 

[alamo5000]

IMO there are too many variables involved to just have a one stop shop for answers when diagnosing problems.

I personally think the thread should be 'stuff you should know before building an AR'. Something like that would help new people get the right stuff from the get go, but even then you will have a vocal few arguing about stuff that doesn't need to be argued about.

 

[Evintos]

The solutions for the sample issues you've listed (5 out of the 6) most often requires messing with the gas system portion of operation whether reduce gas flow or volume, increase gas flow or volume, increase or decrease mass. This is largely due to the fact that most of the issues comes from fixed gas port sizes. The option is either buy new barrel with a different gas port size or weld up the port you have now. Neither of these two is something an end user really wants to do.

Like all semi-auto firearms, the 2nd big issue tends to be people using magazines that are poor quality or in poor condition. Somewhat rare these days.

The next is either out of spec or broken parts. Solution - replace parts.

The perfect solution is to shoot a single type of ammunition only and select a barrel with a gas port size that is optimal for that ammunition with good quality magazines.

The best thing anyone can do is take a video of the problem, preferably in slow motion. 2nd best thing, pictures. Most people have smart phones these days with great cameras. It makes it much easier for people to diagnose issues. Also details matter, the more the better. Way too many people asking for help with basically "my shit don't work" without ever listing details such as temperature, ammo, magazine, parts types, failure rate, attempted remedies, etc.

 

[Milf Dots]

Videos from "School of the American Rifle" are very informative, they are one of the best resources on the subject of ARs.

@lowlight Perhaps a collaboration between SOTAR and SH might be worth investigating?

School of the American Rifle

The Ultimate Source for technical AR15 stuff Course Availability our course Shop Our Webstore BCG Inspection Buy Sotar BCG 3 Bore & Gas System Gauge Set Join Our Social Community This is a 2 day in…

www.schooloftheamericanrifle.com

 

[Mike_in_FL]

Things I always see in the troubleshooting threads/questions.

Not tuning an AGB, i.e., load one round in magazine and keep adding gas until lock back occurs plus one click for reliability.

Not running a new build wet, wet, and more wet. Especially get oil inside gas chamber of carrier to lube new rings a bit. Not enough rounds through a brand new build to break it in and posting for help.

Not being able to discern too much gas from too little. Like the BCG is traveling too fast to reliably feed rounds from the magazine. Usually with a build with an AGB but didn't perform the one round lock back.

People seeming to have a too little gas problem and others suggesting adding an AGB. Can we all finally agree that a wide open AGB won't add any gas compared to a standard gas block? Same situation and people immediately suggesting drilling open gas ports rather than tuning with springs and removing weights from buffers. Sure opening up a port will work but now you're immediately spending $100 or more on an AGB when you may not have even needed it.

 

[357Max]

Videos from "School of the American Rifle" are very informative, they are one of the best resources on the subject of ARs.

@lowlight Perhaps a collaboration between SOTAR and SH might be worth investigating?

School of the American Rifle

The Ultimate Source for technical AR15 stuff Course Availability our course Shop Our Webstore BCG Inspection Buy Sotar BCG 3 Bore & Gas System Gauge Set Join Our Social Community This is a 2 day in…

www.schooloftheamericanrifle.com

SOTAR is a solid resource. Anyone that wants to get serious about building AR’s should take the master armorers class from him (Chad).

He is currently putting together some online training & when ready it might make sense for him to get a commercial account on here.
I’ll plant the seed with him.

There is a treasure trove of knowledge already on this forum if one is willing to search.

Below is a thread I did on a large frame AR that was built in the SOTAR master armorers class.
Even when everything is put together correctly odd problems can happen & you dam sure can’t tell if a barrel will shoot based on guaging or inspection.

DPMS large frame AR308 Polishing a turd (trouble shooting with solutions)

During this covid lock down I decided to try chasing down the accuracy and reliability issues I've been having with a newly built 80% LR/DPMS 308. Initially I started this thread looking for some input on a strange bolt issue. I'm now updating it to be sort of a build/trouble shooting large...

www.snipershide.com