I have a lot of experience with the M16 and a little with the AR15.  After thousands of rounds, I can only recall one part ever breaking.  The pin that holds the front sling swivel broke when I was walking back from the pits at a match.  When the rifle bounced off of the paved range road I about had a heart attack.  This is the only part I have ever had fail.  We have all seen the recommended spare parts lists, but what have you actually had to replace because of wear or breakage?

My extrator broke, it wasn't that old.  After that experience I stocked up on extra bolts, pins and springs, not that they broke on me but they can be easily lost.

Never had a single part break or wear out on an AR that was factory-built and given proper maintenance. And that is after a LOT of use.

On an M16 that saw heavy 9mm usage I've had both hammer and trigger pins break, and I routinely replace the full set of lower fire-control springs every 5,000 rounds. But again, with proper maintenance, quality ammo and care not to overheat the weapon, I haven't even had an extractor failure on my shortiies.

They keep going and going and going.....

My selector fails to switch to auto, but i'll get into trouble if i put the correct part in it's place.

Had a bolt break in haft at the cam bolt pin hole. Now, I just carry a spare gun!!
VM

I have had a few of the firing pin retainer pins bend on me that had to be replaced.Come to think of it,it was the same rifle.Never had to replace any parts on any other AR.Did see a bolt carrier key shear off in basic training though.

I recently purchased a 9MM upper and have been doing a good bit of shooting in it's new 9MM configuration. EVERYONE keeps telling me I'm gonna break my hammer and or trigger pin.
Exactly why is that? I'd appreciate that bit of info. Thanks

Quoted: On an M16 that saw heavy 9mm usage I've had both hammer and trigger pins break, and I routinely replace the full set of lower fire-control springs every 5,000 rounds. They keep going and going and going.....

Quoted: I recently purchased a 9MM upper and have been doing a good bit of shooting in it's new 9MM configuration. EVERYONE keeps telling me I'm gonna break my hammer and or trigger pin. Exactly why is that? I'd appreciate that bit of info. Thanks Quoted: On an M16 that saw heavy 9mm usage I've had both hammer and trigger pins break, and I routinely replace the full set of lower fire-control springs every 5,000 rounds. They keep going and going and going.....

I've been thinking of getting a 9mm upper, so I do research now and again.
I read that the hammer needs to be swapped with, I think, a smaller one (it will still work on 5.56) and a different buffer as well.
Also read that the Oly 9mm bolts break a lot.

Do a search in the topics and you'll find more details from others.

Sorry I can't help you more, still looking myself.

I've never had anything break in a .223 AR, ever! But, I have had 7.62X39 bolt lugs give out.

I haven't ever had a part break on an AR-15.

I had an extractor break after only 400 rnds. This was on a kit upper. I replaced it w/ one that seemed somewhat beefier with a blue extractor spring insert (as opposed to the original black one). No problems since.

I've never had a part break yet either.
I do lose those damn firing pin retainers tho!

Only part that I have ever had break was the feedlip on a USGI 30 rounder. Don't know if that is technically part of the gun though.

Originally posted by tony_k

On an M16 that saw heavy 9mm usage I've had both hammer and trigger pins break.

You need to install the Colt white-metal hammer/trigger pins.  

I don't know if this qualifies as parts breakage, but I had a Oly-ARms CAR15 with the standard Oly carbon steel barrel, after ~5,000-10,000 rounds, the hole for the gas under the front sight used to activate the bolt, enlarged. It manifested in feeding/extraction problems. I found out what the problem was because I sent whole gun to Bushmaster, and the 'smith told he measured the hole diameter, and it was was off. This was back in the days when Oly didn't have the life-time guarentee stated anyways. This was back in 1993.

I was firing my ar15 one day, and it stop extracting, I changed out the spring and plastic deally-bob underneath the extractor and everything was back to normal.  This is after 7,000 - 10,000 rounds.

s0ulzer0
I would definitely recommend going with a COLT upper w/colt bolt and carrier. I have had NO problems yet. Just wondering about those dam trigger and hammer pins. Sounds like I should replace them before they become a problem.
Thanks!

Quoted: I've been thinking of getting a 9mm upper, so I do research now and again. I read that the hammer needs to be swapped with, I think, a smaller one (it will still work on 5.56) and a different buffer as well. Also read that the Oly 9mm bolts break a lot.

No parts breakage with me in many thousands of rounds of 556. I only shoot Bushy and Colt and my guess is that's a plus.

One part only...   Mag release..  

In my six years as an armorer in a 3rd/4th echelon shop, the only thing I usually saw broken in an M16/M4 were extractors (The edge of the hook that grasps the cartridge rim would chip off).  Most parts replaced were due to wear. Upper receivers, barrels, bolts, etc.  I saw every once and a while rifles that had the forward assist retaining roll pin break.  

There were 3 M16A2 run over my an Amtrac, but thats a different story.....

Quoted: Originally posted by tony_k On an M16 that saw heavy 9mm usage I've had both hammer and trigger pins break. You need to install the Colt white-metal hammer/trigger pins.

That's what I did ... a little late. I bought a complete 635 SMG and swapped on the upper, but never bothered to put in the white pins .... a coupla thousand rounds later, during a detail strip, I found both pins had broken in the middle. Gun still ran fine but the broken pins allowed the fire-control parts  to wobble, and if I hadn't caught it quickly it could have enlarged the pin holes. Never again!

No problems since I switched to the hardened SS pins. They cost $10-$20 ea. but are definitely worth it, unless you''re into welding up holes in aluminum receivers.

Yup, on a semi AR you need to switch to a 9mm hammer, which I believe will still work with .223. (The FA M16 hammer is identical for both calibers.)

Quoted: I recently purchased a 9MM upper and have been doing a good bit of shooting in it's new 9MM configuration. EVERYONE keeps telling me I'm gonna break my hammer and or trigger pin. Exactly why is that? I'd appreciate that bit of info. Thanks Quoted: On an M16 that saw heavy 9mm usage I've had both hammer and trigger pins break, and I routinely replace the full set of lower fire-control springs every 5,000 rounds. They keep going and going and going.....

The pin breakage only seems to affect some guns, but it's worth putting in the hardened pins in ANY AR. They work fine with all calibers and have no drawbacks.

The problem is caused by a design flaw in the 9mm upper due to the use of what is basically the same upper for both calibers. The original 5.56 version utilizes a locking-bolt mechanism, but for 9mm they had to either heavily redesign the gas operating system or go to a simple blowback operation.

Like the AR15/M16 series, the 9mm upper was developed first for military applications and began as a full-auto design. But with the closed-bolt blowback system in the 9mm, rate of fire must be kept down to avoid out-of-battery ignition. Safe levels are around 1,200 RPM, but Colt (and the military) decided to keep it well under 1,000 RPM for safety reasons.

The way to reduce rate of fire is to increase bolt and buffer mass. Colt developed the heaviest buffers it could, and even went to hydraulic buffers (first used in 9mm guns), but it was still limited in the bolt-mass department: The 9mm bolt had to fit in the 5.56 receiver''s bolt channel, and there was no way to get enough mass to slow it down.

So instead, Colt redesigned the bottom of the bolt. While the 5.56 has a gentle ramp to "ease back" the hammer during recoil, for the 9mm Colt designed in a sharp corner that put much more pressure on the hammer/spring -- in effect, using the hammer spring as an additional "brake."

This succeeded in keeping the ROF down. Unfortunately, it also drives the hammer back HARD at the end of its travel, and it often ended the swing by hitting the disconnector -- again, HARD. This impact was transmitted through the disconnector to the trigger as well.

All that "hammering" eventually causes the hammer and trigger pins to break. So Colt came up with the hardened "white" pins that willl not break, and installed them in ARs and M16s that left the factory in 9mm.

Hope that long explanation helps.

An extractor broke, once.

Quoted: Hope that long explanation helps.

tony_k
Yup! That info helps alot. I got those ss pins
when I purchased the upper. They're around here somewhere. Sounds like I better get them intsalled before my $5000.00 M16A1 receiver is in desperate need of repair.
Thanks gain!

Quoted: s0ulzer0 I would definitely recommend going with a COLT upper w/colt bolt and carrier. I have had NO problems yet. Just wondering about those dam trigger and hammer pins. Sounds like I should replace them before they become a problem. Thanks!

I was thinking the Oly so I could use the SOCOM.com mag block and unmodified (and cheap) Sten mags.
Isn't RRA's 9mm upper same form as Colt?
I just can't bare buying a Colt upper, no offence.

Quoted: I was thinking the Oly so I could use the SOCOM.com mag block and unmodified (and cheap) Sten mags. Isn't RRA's 9mm upper same form as Colt? I just can't bare buying a Colt upper, no offence.

No offense taken! I haven't checked out the SOCOM.com mag blocks yet. I am heading into work shortly but will do so asap.

Here is my mag block. It is a one piece system. Also really hefty. But what is nice about it is you just insert in mag well and it is held in place by the mag catch. Simply insert magazine into block and it is held in place by block. To release magazine slightly press mag release. To drop mag block push mag release all the way in.
I have two of these I purchased awhile back on ebay. Anyway they work great! Good luck with your purchase and start shopping for a muzzle break! With a shorty barrel you'll need it.

Is there any downside to the black spring inserts in the extractor spring? Does it cause more wear on the extractor/make it more prone to breakage?

Quoted: Quoted: I was thinking the Oly so I could use the SOCOM.com mag block and unmodified (and cheap) Sten mags. Isn't RRA's 9mm upper same form as Colt? I just can't bare buying a Colt upper, no offence. No offense taken! I haven't checked out the SOCOM.com mag blocks yet. I am heading into work shortly but will do so asap. Here is my mag block. It is a one piece system. Also really hefty. But what is nice about it is you just insert in mag well and it is held in place by the mag catch. Simply insert magazine into block and it is held in place by block. To release magazine slightly press mag release. To drop mag block push mag release all the way in. I have two of these I purchased awhile back on ebay. Anyway they work great! Good luck with your purchase and start shopping for a muzzle break! With a shorty barrel you'll need it.

SWEET!!!
The url for the mag block for sten mag use is here:
www.socommfg.com/
It works about the same as yours, but has it's own mag release to eject the sten mags.
Only hit the AR mag release to drop the block.

I've read only the Oly will work with this.....
The RRA uses Uzi mags and a mag block like yours. So I guess it's the Colt style 9mm upper.