What are the most common failure modes of the AR15?

**atn729** · 01-24-21, 22:28

I'm looking into what spare parts to buy to future proof my current set ups.

What are the most common failure modes in an AR15? What spare parts is one most likely to need? What is the best source for these parts?

Right now I'm not very experienced with rifle failure as I've only done 2 classes and my most used rifle only has 5k through it.

**MC_Oper8or** · 01-25-21, 01:20

Bolts. Bolt parts. Barrels. One of every spring and detent at least.

Find then wherever you can at this point. Primary Arms is my go to.

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**titsonritz** · 01-25-21, 01:22

Focus on the bolt/BCG, that is most of the heavy lifting is done, get gas rings, extractor, spring & insert, firing pin, FP retaining pin, cam pin, ejector, extra bolt or two if possible. Beyond that, spring and detents. And barrels.

ETA: My go to place for parts would be Primary Arms, BCM and Forward Controls.

**vicious_cb** · 01-25-21, 02:11

Originally Posted by atn729

I'm looking into what spare parts to buy to future proof my current set ups.

What are the most common failure modes in an AR15? What spare parts is one most likely to need? What is the best source for these parts?

Right now I'm not very experienced with rifle failure as I've only done 2 classes and my most used rifle only has 5k through it.

User error...

**17K** · 01-25-21, 08:21

I keep enough parts to build up another set of receivers.

Extra gas rings, extractor w/spring and insert, firing pin, firing pin retaining pins, bolt, buffer springs, and hammer springs.

**MikhailBarracuda91** · 01-25-21, 08:38

Nobody mentioned gas tube yet.

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**Clint** · 01-25-21, 08:46

The most common stoppage inducing item is the magazine.

PMAGs are the most reliable, so stock up on those.

The easiest way to get a bunch of spare parts is to pick up a complete BCG.

**Joe Mamma** · 01-25-21, 08:49

All good suggestions above. I would say the first and most likely problem area would probably be related to extraction, so extractor spring, insert, extractor, o-ring (if you use it), etc. An easy way to address this is to simply have a spare bolt (with extractor, gas rings, etc. already installed). An even better way would be to have a spare bolt carrier (complete with bolt etc.) because that would address some other common sources of malfunctions.

If you don't know, there are many different types and brands of extractor springs. It would be a good idea to find what works in your guns, and stock up on the exact same ones.

Don't overlook good magazines and good ammo for your guns. You didn't ask, but those are areas that are much more likely area to cause malfunctions in my humble opinion.

Joe Mamma

**atn729** · 01-25-21, 09:12

Originally Posted by Joe Mamma

All good suggestions above. I would say the first and most likely problem area would probably be related to extraction, so extractor spring, insert, extractor, o-ring (if you use it), etc. An easy way to address this is to simply have a spare bolt (with extractor, gas rings, etc. already installed). An even better way would be to have a spare bolt carrier (complete with bolt etc.) because that would address some other common sources of malfunctions.

If you don't know, there are many different types and brands of extractor springs. It would be a good idea to find what works in your guns, and stock up on the exact same ones.

Don't overlook good magazines and good ammo for your guns. You didn't ask, but those are areas that are much more likely area to cause malfunctions in my humble opinion.

Joe Mamma

Thanks for the additional suggestions. I mostly use pmags or OKAY surefeeds. I have some spare bolts but I will look into extraction related parts.

Thanks so much for your help.