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Old December 31, 2012, 02:47 PM   #1
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Spare parts

Anything mechanical has a failure rate, what are the most commonly replaced worn parts on the AR15 platform (S&W M&P), what would be reasonable to try and acquire to make sure the one I own lives forever.

Obviously two of everything on it would be grand, but now likely more like 3 grand...

I would just like to know if something breaks I have one in my closet, not have to scour the web after the fact.

Any resources on duty cycles on the individual parts would be great.

Thanks in advance.
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Old December 31, 2012, 03:05 PM   #2
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Look at what is critical to operation and what takes a beating or heavy use:

- firing pin
- bolt, lugs can break off but more likely the extractor, extractor spring, ejector spring
- bolt cam
- bolt o-rings
- hammer spring
- trigger group
- buffer spring
- buffer retaining pin

Then I would look at what could easily get lost during field or detail strip:
Pretty much every pin and spring, and the cotter pin that secures the firing pin.

To make it easy, maybe a lower parts kit and a spare complete bolt. Might want to add a gas tube. The bolt would be my top priority or a bolt rebuild kit.

Sure I missed a few things but that is my first thought.
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Old December 31, 2012, 03:12 PM   #3
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Aside from just some manufacturing fault or freak accident, any idea what the duty cycle on any of these are?

I have not owned it long, < 1k rounds since it was new, cleaned meticulously after every range visit.

I see things that were once black are now shiny, but cannot see any visible signs of anything other than cosmetic wear on anything.

essentially is there a point where something should be replaced because of use *Just to be sure* like changing the oil, or keep it clean then run it till it breaks?
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Old December 31, 2012, 03:40 PM   #4
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A spare bolt, firing pin, and complete lower parts kits will keep your AR running for a very long time...

Before the craziness, ~$130 of parts.
Hk USP 45 Expert, USP 40, USP 9, SIG P226, S&W M&P9, Hk 4, Makarov, Desert Eagle 40, Beretta FS92 Centurion, Kimber TLEII 1911A1, Glock 22, SIG P225, 1943 Rem Rand 1911A1, S&W mod 64, Walther PPQ, SIG P229, Browning BDA 45 (SIG P220), Hk45, SIG P230
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Old January 1, 2013, 07:19 PM   #5
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Ok, thanks folks.
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Old January 1, 2013, 07:34 PM   #6
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Here is a similar thread
Tolerate- allow the existence, occurrence, or practice of something that one does not necessarily like or agree with , without interference.
If you have some time IMO this is worth a listen/watch but it takes a few minutes to really get going . or a picture of Mohamed
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Old January 1, 2013, 10:52 PM   #7
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If you keep spare parts you are much more likely to need one because you lost something than you ever will be because you wore something out or broke it.
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Old January 2, 2013, 12:56 PM   #8
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A complete bolt should be in every AR owners range bag. After that, a lot of it depends on the specifics of your build.

Bolt carrier with a new cam and firing pin would be good parts to add after the bolt.

I would probably go with a gasblock and gas tube next.

Next a charging handle.

Then a complete set of springs.

Then a bolt rebuild kit.

I don't use buffer retainers or forward assists at all. They are prone to breakage so I just strip them out if I end up with a lower that has those parts and never buy them when I build new.
Good Shooting, MarkCO
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