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Posted: 1/7/2012 11:16:05 AM EDT
Hello @all

Why can an AR-15 Bolt crushing? Mine is cracked today on one side of the big hole, where the big pin (sorry, i don't know the english word) hold the bolt into the carrier. A Friend of me hat a completely broken Bolt at exact the same point last week (halfe bolt in the gun, halfe in the boltcarrier). What's the reason for the problem? Is this a "normal" AR Problem?
Thank you for Help!
Link Posted: 1/7/2012 11:40:48 AM EDT
This is one of the places where AR bolts can break. The other spot is at the locking lug on either side of the ejector. The cracking does not occur that often, but if you shoot AR-15's enough, you will break one, or see one that breaks.

How many rounds have you fired out of this AR?

Who made your AR?

While is it super easy for American's to buy new bolts, how simple is it for you?
Link Posted: 1/7/2012 11:42:52 AM EDT
It can happen for more reasons than I can list.

What brand of weapon are you shooting. How many rounds have you shot with this particular bolt? Is the weapon your friend is shooting the same brand. Are you shooting reloaded ammo or factory?

There are mny here who can help, I just gave you a place to start.
Link Posted: 1/7/2012 12:26:15 PM EDT
Improper heat treat can cause stress at that point. That's the primary cause...metallurgy...
Another place bolts/carriers fail is the two allen screws that are staked to the carrier key.

Link Posted: 1/7/2012 1:18:46 PM EDT
Thanx for your replies!
my ar is an buildet one. upper ?? (has a "keyhole" mark on the right), lower noveske, barrel an m4 style, non chrome lined 16" 1/9turn of unknown brand, bolt and carrier also unknown. friend has a colt lower, barrel and bolt.
i fired under 2'000 rounds, so it should not happend after this low number of rounds in my opinion. i've shoot reloads with a 62gr fmj, federal 205 primers, AA2230 Powder and they go about 2995fps out of a 20" Barrel. My friend only shoot factory ammo.

buy a new bolt here is like buy a complete gun. a police authorisation is needed
stupid firearm laws here. they are against law abiding citizens, not against criminals.
Link Posted: 1/7/2012 2:54:14 PM EDT
The "keyhole" mark means that Cerro Forge was the company that produced the Aluminum Forging.

The other parts on your upper half sound like a combination of companies.

The minimum bolt life on an M-4 is 5,000 rounds, so your 2,000 rounds is low.

Midway Switzerland (http://www.midwayschweiz.com/) sells AR-15 bolts.
Link Posted: 1/7/2012 3:08:39 PM EDT
Good Luck my friend.





Bill
Link Posted: 1/7/2012 3:12:11 PM EDT
Link Posted: 1/7/2012 3:50:29 PM EDT
[Last Edit: 1/7/2012 4:03:40 PM EDT by Saddlerocker]
The bolt carrier group is the heart of the rifle

When you buy a new one, do your best to buy quality (try to find an HPT/MPI bolt)
Its the most important part of this rifle in my opinion

And as others have said, that is very early for a bolt to break, but it is a common area where yours cracked (cam pin hole)

Edit:
After looking at Midway, you dont have any great options.
DPMS/Bushmaster/AR Stoner/Olympic
If these are the only ones you can fine, I guess get a Bushmaster or DPMS and hope for the best.
If you have the money the AR stoner Nickle Boron seems it might be the best. From that site at least. if you can find better quality it is worth it to spend the money.
http://www.midwayschweiz.com/apps/ebrowse.exe/browse
Link Posted: 1/7/2012 7:43:00 PM EDT
Originally Posted By HeavyMetal:
Bolts breraking at the cam pin hole is indicitive of a shitty bolt.

Cheap bolts break at the cam pin hole at low round counts, good bolts break at the extractor cut lugs at high round counts.

BTW, Filthy 14 is arround 25,000 rounds on its second bolt.


Yep.

Though i have 10,847 rounds on an Olympic Arms bolt of all things and it hasnt broke a lug or at the cam pin yet. Even on its original extractor as well.
Link Posted: 1/7/2012 7:47:01 PM EDT
This is why I run a MP tested bold and carrier .
Link Posted: 1/8/2012 2:06:12 AM EDT
cam pin hole, that are the words i don't know

Midwayswiss is my first adress for spare parts in short time. its not cheap, but if the option is waiting for months, its the only possibility. i was looking for the les bear bolt, because it is in the middle price class and les bear stands normaly for good quality. and midway has the bolt in stock. what do you think about it? is it worth the money, or should i go for a dpms or bushmaster?

btw, midway swiss has a couple of barrels listet. does "chrome moly matte" means that the bore is chrome lined (what i'm looking for), or is chrome moly the type of steel used for the barrel?

best regards
swiss arms
Link Posted: 1/8/2012 7:08:03 AM EDT
Link Posted: 1/8/2012 7:30:53 AM EDT
Les Baer uses bolts and bolt carriers from Young Manufacturing. They are quite good.

Chrome-Moly means that the steel contains Chromium and Molybdenum. It does not mean that the bore is chrome lined.
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