When are parts worn out ar15

xandi · January 23, 2018, 06:59 AM

Hi
I was Thinking about a ar thread about nubey Ar lube questions and it occurred to me, I don’t really know when a bolt or bcg is worn out or needs replacing.
What is the life span of the interals of a rifle? How do I know if i need to replace something
Thx

Mobuck · January 23, 2018, 07:42 AM

"What is the life span of the interals of a rifle?"
Far longer than most non-competitive shooters will ever need.
"How do I know if i need to replace something"
When a malfunction shows up on a dependable rifle suddenly or on a consistent basis.
I've not had a single broken part on an AR used for casual shooting. It would be expected that things like gas rings, extractors, and ejectors might be the first parts to show wear or simply break. Magazine issues will present problems more often than broken/worn parts.

Slamfire · January 23, 2018, 08:17 AM

Generally speaking AR15's start cracking bolt lugs around 10,000 rounds. Better made bolts go 30,000 rounds. Throat erosion will eat up a barrel around 5000 rounds, chromed barrels longer. Those are the major items that will require an over haul of the rifle.

Gas rings wear out, expect them to last around 5000-6000 rounds. When the bolt "falls" into the carrier, under its own weight, or the weapon is short stroking, replace the rings.

A bud of mine worked on the rebuild lines at Anniston Army Depot. After a rebuild one M4/M16 was selected out of a lot and shot 6000 rounds. None, in his experience, failed the endurance test.

All service rifles are light weight rifles, not meant for an infinite service life. All mechanical items are designed for a load and a duty cycle. The driving requirements that Stoner had to meet was a weight requirement and a 6000 round endurance requirement. After 6000 rounds the military considered it acceptable to ship the rifle back to depot where any or all parts are scrapped in the rebuild process. Today's improved material process technology will have extended the lifetime of all mechanical parts subjected to stress and strain.

Trigger parts should out last the bolt and barrel. If you are firing hot ammunition you can expect extractor failures. The case should not stick in the chamber, when the extractor has to pull the case out of the chamber it will fail in time, as the extractor is simply a thin piece of metal. Ideally, you want as little case to chamber friction as possible, so the case simply pops out when the bolt opens. That is why you see several versions of gas lubriction through chamber flutes on more advanced AR15 actions.

This is XTRAN technology, light chamber fluting which floats the upper 2/3's of the case from the chamber, to reduce extraction forces and improve extraction reliablity.

Just keep everything nicely lubricated, keep your weapon clean, and you should be able to shoot more ammunition than your wallet can afford without malfunctions.

odugrad · January 23, 2018, 09:47 AM

The best thing to do is have spare parts on hand. Then it won't matter because you'll have all the parts to keep your rifle running indefinitely.

I would get several sets of gas rings, cam pins, firing pins, a couple lower parts kits, extractors and extractor springs, spare bolts (if you're able), firing pin retaining pins, miscellaneous springs/detents, a gas tube or two, buffer springs.

Did I leave anything out?

xandi · January 23, 2018, 10:17 AM

So a bolt carrier should last 10k+
Would there be any sort of eching from the escaping gas?

MarkCO · January 23, 2018, 10:30 AM

Bolt carriers will go 100s of thousands of rounds. Bolts should go upwards of 50K unless they are poor quality or the rifle is not properly set up.

When I replace barrels (10 to 15K), I rebuild the bolts with new springs (Colt gold with black buffer for the extractor) and gas rings and I might replace the actual extractor every other barrel. I would not stretch gas rings past 15K. Realize that on an overgassed rifle, there is more wear. If you use slower powders too, more wear. I have seen bolts needing to be rebuilt in the 7-8K range with those parameters.

I average about 30K a year on my AR15s and usually rebuild 2 a year.

AR10 pattern ARs are a whole different animal and they wear out faster and have different issues. (What Slamfire was talking about)

Slamfire · January 23, 2018, 10:30 PM

Quote:

Bolts should go upwards of 50K unless they are poor quality or the rifle is not properly set up.

I remember reading a thread, somewhere, where the forum members were asked to post the round counts till bolt cracking. Generally bolts were beginning to crack around 10,000 rounds, but many took thousands more rounds before they cracked. Last year I was talking to AMU shooters about bolt lifetime, they have special material bolts that don't show cracks till around 30,000 rounds.

I have one bud who is shooting a 6mm or 6.5 Grendel cartridge in his AR15. The gunsmith supplied a spare bolt as the first bolt often cracked before the barrel was shot out. As for AR10 type rifles, I have no idea of bolt life, but if they are made to the typical safety factor of two, you can expect them to start cracking around 10,000 rounds.

Nathan · January 24, 2018, 06:54 AM

A part is worn out when:

- when it fails a function check of the part or system
- when it breaks
- when it falls out of gage limit like exceeding a “field” gage for headspace

Charlie98 · January 24, 2018, 09:59 AM

Friend of mine had a discount upper on his AR, I don't recognize the builder. After about 3000 rounds the gas rings failed, they actually sheared off, causing cycling issues. Last year, on a trip to WY, the bolt sheared 3 of the lugs; I'm going to guess the round count at that point was about 5000. Soooo... components DO matter. I have probably twice that many through my RRA upper, without any issues.

Charlie98 · January 24, 2018, 10:02 AM

Quote:

I remember reading a thread, somewhere, where the forum members were asked to post the round counts till bolt cracking. Generally bolts were beginning to crack around 10,000 rounds, but many took thousands more rounds before they cracked.

There is an ongoing thread over at ARF about this, the most substantive evidence came from a guy that runs a machine gun rental place in Las Vegas. I'm not one to go back on a multipage thread and read everything, but I did with this one, and it was quite enlightening. If memory serves, the 10-15K round mark is the typical lifespan of a bolt.

xandi · January 24, 2018, 08:58 PM

Any ideas for the round count lifespan of an upper or/and lower receiver? I imagine it’s mesured in barrels, but just how long is one good for? 6-7 barrel changes? Where will one fail at? The threads for the barrel but? Take down pins? One oops that was bullseye not win748 handload?

MarkCO · January 24, 2018, 10:32 PM

I looked at a buddies Bushmaster that had about 200K on it, receivers were sloppy, but still ran.

My main 3Gun rifle just got its 4th barrel. I rebuild the bolt and swap in a new barrel and buffer spring each year. It has 12-13K through it annually. Receivers are fine at almost 40K.

Charlie98 · January 24, 2018, 11:45 PM

I don't think either the upper or lower receiver are issues... they don't bear the brunt of pressure or recoil.

444 · January 25, 2018, 07:27 AM

I am NOT saying this is good practice.
But...........I have owned AR15s since the early 1980s and along the way I purchased more of them.
Over the years I have shot some of them quite a bit. One of them, I put close to 10,000 rounds of Wolf ammo (steel cases, laquered cases.....) alone (not counting other ammo I shot through the rifle). I know this because back in the day, at our local gunshows, Wolf ammo used to be approx. $70 a case (1000 rounds) and I used to keep track of how many cases I had purchased. I have taken numerous carbine classes, some of which we fired close to 2000 rounds in a week (this wasn't Wolf).....................I have shot them a fair amount: I know there are people who have shot their rifles more, but some of mine have far more rounds through them than the average AR owner will ever fire out of theirs.

I have rebarreled them, but I am still using the original bolts with the original extractors, extractor springs, rings...................I have never rebuilt any part of the bolt.

Again, this probably isn't best practice, but it is what it is.

Slamfire · January 25, 2018, 09:04 AM

This is worth reading:

High round count AR/M4's (over 100,000 rounds) and how they have handled on our range

https://www.ar15.com/forums/ar-15/Hi...ge/118-677135/

What % of bolts fail MPC testing?

https://www.ar15.com/forums/ar-15/-/12-290916/

Charlie98 · January 25, 2018, 10:03 AM

^^^ That's the thread I was talking about. I see it's up to 30 pages now...

HankC1 · January 27, 2018, 08:37 AM

Quote:

My main 3Gun rifle just got its 4th barrel. I rebuild the bolt and swap in a new barrel and buffer spring each year. It has 12-13K through it annually. Receivers are fine at almost 40K

Good to know upper receiver last. I always wonder if a new upper receiver is needed when barrel is worn out. BCG is steel, upper is aluminum, steel riding on aluminum is generally not a good combination. you keep it wet? What lub you use in upper receiver?

rickyrick · January 29, 2018, 07:22 PM

I would think if a person can run enough ammunition through a gun to wear it out, then repairing the rifle wouldn’t be nothing but a minor inconvenience to the owner. It would definitely not be a financial burden at all.

Road_Clam · January 30, 2018, 06:51 AM

Quote:

Originally Posted by Slamfire

This is worth reading:

High round count AR/M4's (over 100,000 rounds) and how they have handled on our range

https://www.ar15.com/forums/ar-15/Hi...ge/118-677135/

Slamfire, thanks for the link that's a great read on real world AR wear and tear.

I own 4 different AR configurations and generally the only component I've observed that takes elevated wear is my bolt cam pins. i'm just a recreational shooter and I make it a point to keep my ar's reasonably lubed. I prefer to minimize the wear on the bolt cam pin by keeping it lubed with Mobil 1 grease.

January 23, 2018, 06:59 AM	#1
xandi Senior Member Join Date: April 10, 2015 Location: ga Posts: 321	When are parts worn out ar15 Hi I was Thinking about a ar thread about nubey Ar lube questions and it occurred to me, I don’t really know when a bolt or bcg is worn out or needs replacing. What is the life span of the interals of a rifle? How do I know if i need to replace something Thx

January 23, 2018, 08:17 AM	#3
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Generally speaking AR15's start cracking bolt lugs around 10,000 rounds. Better made bolts go 30,000 rounds. Throat erosion will eat up a barrel around 5000 rounds, chromed barrels longer. Those are the major items that will require an over haul of the rifle. Gas rings wear out, expect them to last around 5000-6000 rounds. When the bolt "falls" into the carrier, under its own weight, or the weapon is short stroking, replace the rings. A bud of mine worked on the rebuild lines at Anniston Army Depot. After a rebuild one M4/M16 was selected out of a lot and shot 6000 rounds. None, in his experience, failed the endurance test. All service rifles are light weight rifles, not meant for an infinite service life. All mechanical items are designed for a load and a duty cycle. The driving requirements that Stoner had to meet was a weight requirement and a 6000 round endurance requirement. After 6000 rounds the military considered it acceptable to ship the rifle back to depot where any or all parts are scrapped in the rebuild process. Today's improved material process technology will have extended the lifetime of all mechanical parts subjected to stress and strain. Trigger parts should out last the bolt and barrel. If you are firing hot ammunition you can expect extractor failures. The case should not stick in the chamber, when the extractor has to pull the case out of the chamber it will fail in time, as the extractor is simply a thin piece of metal. Ideally, you want as little case to chamber friction as possible, so the case simply pops out when the bolt opens. That is why you see several versions of gas lubriction through chamber flutes on more advanced AR15 actions. This is XTRAN technology, light chamber fluting which floats the upper 2/3's of the case from the chamber, to reduce extraction forces and improve extraction reliablity. Just keep everything nicely lubricated, keep your weapon clean, and you should be able to shoot more ammunition than your wallet can afford without malfunctions. __________________ If I'm not shooting, I'm reloading.

January 23, 2018, 10:30 AM	#6
MarkCO Senior Member Join Date: October 21, 1998 Location: Colorado, USA Posts: 4,308	Bolt carriers will go 100s of thousands of rounds. Bolts should go upwards of 50K unless they are poor quality or the rifle is not properly set up. When I replace barrels (10 to 15K), I rebuild the bolts with new springs (Colt gold with black buffer for the extractor) and gas rings and I might replace the actual extractor every other barrel. I would not stretch gas rings past 15K. Realize that on an overgassed rifle, there is more wear. If you use slower powders too, more wear. I have seen bolts needing to be rebuilt in the 7-8K range with those parameters. I average about 30K a year on my AR15s and usually rebuild 2 a year. AR10 pattern ARs are a whole different animal and they wear out faster and have different issues. (What Slamfire was talking about) __________________ Good Shooting, MarkCO www.CarbonArms.us

January 24, 2018, 09:59 AM	#9
Charlie98 Senior Member Join Date: September 6, 2006 Location: Great state of Texas Posts: 1,077	Friend of mine had a discount upper on his AR, I don't recognize the builder. After about 3000 rounds the gas rings failed, they actually sheared off, causing cycling issues. Last year, on a trip to WY, the bolt sheared 3 of the lugs; I'm going to guess the round count at that point was about 5000. Soooo... components DO matter. I have probably twice that many through my RRA upper, without any issues. __________________ _______________ "I have this pistol pointed at your heart!" "That is my least vulnerable spot."

January 24, 2018, 08:58 PM	#11
xandi Senior Member Join Date: April 10, 2015 Location: ga Posts: 321	Any ideas for the round count lifespan of an upper or/and lower receiver? I imagine it’s mesured in barrels, but just how long is one good for? 6-7 barrel changes? Where will one fail at? The threads for the barrel but? Take down pins? One oops that was bullseye not win748 handload? Last edited by xandi; January 24, 2018 at 09:10 PM.

January 23, 2018, 07:42 AM	#2
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	"What is the life span of the interals of a rifle?" Far longer than most non-competitive shooters will ever need. "How do I know if i need to replace something" When a malfunction shows up on a dependable rifle suddenly or on a consistent basis. I've not had a single broken part on an AR used for casual shooting. It would be expected that things like gas rings, extractors, and ejectors might be the first parts to show wear or simply break. Magazine issues will present problems more often than broken/worn parts.

January 23, 2018, 09:47 AM	#4
odugrad Senior Member Join Date: March 13, 2013 Location: The East Coast Posts: 477	The best thing to do is have spare parts on hand. Then it won't matter because you'll have all the parts to keep your rifle running indefinitely. I would get several sets of gas rings, cam pins, firing pins, a couple lower parts kits, extractors and extractor springs, spare bolts (if you're able), firing pin retaining pins, miscellaneous springs/detents, a gas tube or two, buffer springs. Did I leave anything out?

January 23, 2018, 10:17 AM	#5
xandi Senior Member Join Date: April 10, 2015 Location: ga Posts: 321	So a bolt carrier should last 10k+ Would there be any sort of eching from the escaping gas?

January 24, 2018, 06:54 AM	#8
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,331	A part is worn out when: - when it fails a function check of the part or system - when it breaks - when it falls out of gage limit like exceeding a “field” gage for headspace

January 24, 2018, 10:32 PM	#12
MarkCO Senior Member Join Date: October 21, 1998 Location: Colorado, USA Posts: 4,308	I looked at a buddies Bushmaster that had about 200K on it, receivers were sloppy, but still ran. My main 3Gun rifle just got its 4th barrel. I rebuild the bolt and swap in a new barrel and buffer spring each year. It has 12-13K through it annually. Receivers are fine at almost 40K. __________________ Good Shooting, MarkCO www.CarbonArms.us

January 24, 2018, 11:45 PM	#13
Charlie98 Senior Member Join Date: September 6, 2006 Location: Great state of Texas Posts: 1,077	I don't think either the upper or lower receiver are issues... they don't bear the brunt of pressure or recoil. __________________ _______________ "I have this pistol pointed at your heart!" "That is my least vulnerable spot."

January 25, 2018, 07:27 AM	#14
444 Senior Member Join Date: November 20, 2000 Location: Ohio Posts: 3,968	I am NOT saying this is good practice. But...........I have owned AR15s since the early 1980s and along the way I purchased more of them. Over the years I have shot some of them quite a bit. One of them, I put close to 10,000 rounds of Wolf ammo (steel cases, laquered cases.....) alone (not counting other ammo I shot through the rifle). I know this because back in the day, at our local gunshows, Wolf ammo used to be approx. $70 a case (1000 rounds) and I used to keep track of how many cases I had purchased. I have taken numerous carbine classes, some of which we fired close to 2000 rounds in a week (this wasn't Wolf).....................I have shot them a fair amount: I know there are people who have shot their rifles more, but some of mine have far more rounds through them than the average AR owner will ever fire out of theirs. I have rebarreled them, but I am still using the original bolts with the original extractors, extractor springs, rings...................I have never rebuilt any part of the bolt. Again, this probably isn't best practice, but it is what it is. __________________ You know the rest. In the books you have read How the British Regulars fired and fled, How the farmers gave them ball for ball, From behind each fence and farmyard wall, Chasing the redcoats down the lane, Then crossing the fields to emerge again Under the trees at the turn of the road, And only pausing to fire and load.

January 25, 2018, 09:04 AM	#15
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	This is worth reading: High round count AR/M4's (over 100,000 rounds) and how they have handled on our range https://www.ar15.com/forums/ar-15/Hi...ge/118-677135/ What % of bolts fail MPC testing? https://www.ar15.com/forums/ar-15/-/12-290916/ __________________ If I'm not shooting, I'm reloading.

January 25, 2018, 10:03 AM	#16
Charlie98 Senior Member Join Date: September 6, 2006 Location: Great state of Texas Posts: 1,077	^^^ That's the thread I was talking about. I see it's up to 30 pages now... __________________ _______________ "I have this pistol pointed at your heart!" "That is my least vulnerable spot."

January 29, 2018, 07:22 PM	#18
rickyrick Senior Member Join Date: March 15, 2010 Posts: 8,238	I would think if a person can run enough ammunition through a gun to wear it out, then repairing the rifle wouldn’t be nothing but a minor inconvenience to the owner. It would definitely not be a financial burden at all.