Boogieman065

Hey guys,

I have several damages on my bolt and carrier. On the bolt, the star-clusters are rounded off on one side so I had to smooth it down to ensure it doesn't catch and the action is smooth. On the bolt carrier, the fins that sit between the firing pin and the hammer is all chipped off....


How do these damages happen?? Is it common for bolt carriers to get chipped and damaged over time?? I clean after shooting every time and lube it too. It's probably had about 4k rounds through it.

Thanks!

KillermondoDude

PICS!!!!!!!!!!!!!!!!!!!!i!!!!!!!!!!!!!!!

Boogieman065

Some pics:

Here you can see where those fins are chipping off.

Here are the stars of the bolt that have been rounded off:

Whole system:

Action shot

KillermondoDude

Umm might wanna look into a chrome bolt
the m16 based systems have one inherent difficulty which is its a direct blowback bolt system and as such the bolt will go through heat cycles as the gun cycles can cause britteling of the metal

http://www.brownells.com/.aspx/pid=1..._BOLT_CARRIERS

Boogieman065

Cheaper alternative?? How about a certain lube which handles the heat better???


One side note These damages started occuring after I started switching from .223 and .22lr conversions frequently outdoors. The bolts are just left out to cool at a rapid rate outside of the firearm, could that be a major source of the issue? The .22lr bolt is chromed or stainless and has no problem so far. This bolt is falling to pieces though.

Thanks!

KillermondoDude

I cant say for sure but it looks like its got metal fatigue due to heat cycles
Give fatfugg an PM as hes got a shitload of AR based weaponry and will have prolly a better reason/ possible cure

also call your bolts/ upper receivers manufacture as it may be a bad batch of bolts and has been recalled

FatFugg

My only guess on the bolt is that the barrel isn't headspaced properly so it isn't locking completely. As for the carrier, I have no idea. There are others on here with much more experience with AR's then me & I'm curious what their input will be.

You may want to search or post this up on AR15.com. There are a lot of guys that have seen just about everything with AR's & you would probably get the correct answer pretty quick.

Also, I would personally not fire it until you figure out what is happening as is appears the the bolt isn't completely locking in the breach.

Boogieman065

Your theory about headspacing may also be correct because my frontsight is a little lobsided and I can't fix it because it appears as if the barrel was installed slightly too tight to the right.
Ahhh... so many theories...

FatFugg

It should only line up one way. Are the feed ramps on the barrel both even to the bottom of the receiver? Headspace wouldn't make the barrel cock eyed, it would just be too far in or out of the receiver.

Boogieman065

Feed ramps sit perfectly flush. Lines up with teh bottom receiver just fine.

Brianaintright

If the front sight is askew, it might be that the whole assemply might be off and the barrel extension is catching the bolt on extraction.

Is this a factory gun or a parts gun?

This isn't a heat cycle issue, (unless this is a way out of spec bottom of the barrel bolt and carrier) it appears to be a timing issue. Bolt is being extracted prior to completely unlocking. Chipping on the rear of the carrier means it is catching on something, possibly retarding movement and screwing up extraction. Check your lower receiver parts for wear, especially the hammer. Either way, you need a new bolt, that one is done.

Boogieman065

The hammer has some wear on it, not anythig unusual. Where should I get the headspacing done? Anyone here can help me? The only gun smith I know of in Seattle is a rip off.

Brianaintright

Cuervo is a smith. Might check with him. If nothing else he could reccomend someone.

cuervo

I don't think it is your head space. Shooting a .22lr kit threw a quality AR15 will do nothing to damage it. Heat cycling is not an issue with quality AR15 or M16 rifles, quality direct impingement AR15 rifles have been in use for over five decades with our armed forces, no need to muddle the waters or mess up your guns with chrome add-ons or bolt on piston kits. (don't get me started) Lube (as long as your using it) is not your issue, nore will it fix your problem. Without actually seeing your upper I'm only giving my best educated guess on what information I have, which is very little.

-- If you would like to send/bring your upper to the shop I would be willing to check your head space and examine it for free. Call it Good Will and Seasons Greetings. -- :)

This is not common wear on an AR15 bolt/carrier. Lets get a little more info shall we?

- Did the upper receiver come assembled or did you piece it together from parts?
- Who is the manufacturer of the upper receiver?
- Did you mention weather or not your rifle is cycling properly?
- Is it failing to feed or failing to extract?
- How many rounds of .223 have you put threw the rifle?
- How many rounds of 5.56 have you put threw the rifle?
- Is your rifle chambered for .223 or 5.56?

Boogieman065

I would love to come to your shop, but I'm in Seattle... It's quite a drive. I'm going to try Top Guns in Shoreline and if that fails (most likely will), I'll make the trip there.


- Did the upper receiver come assembled or did you piece it together from parts?
It came assembled.
- Who is the manufacturer of the upper receiver?
N/A, it is not marked and no one seems to have a clue. I got it used a while back from a guy who worked for SNS. The lower is Olympic Arms and was made in 2003.
- Did you mention weather or not your rifle is cycling properly?
The rifle shot just fine, I can do the function check on it alright. I only discovered the damage visually while cleaning, no performance related issue.
- Is it failing to feed or failing to extract?
It is feeding and extracting just fine.
- How many rounds of .223 have you put threw the rifle?
Over 1,500 rounds. (since I've owned it)
- How many rounds of 5.56 have you put threw the rifle?
About 100 rounds. (Since I've owned it)
- Is your rifle chambered for .223 or 5.56?
Both

redtazdog

You are gettng bolt bounce, get a H2 buffer and your problems will go away
I had the same problem 15 years ago with one of my builds.

Boogieman065

Check your PM. That'll be great if I could fix all this for 35.00.

I see that you have a lot of ARs, do you think you'll have that part(s) I need for sale?

redtazdog

I have many diferent buffers in many diferent wieghts but I use them
for tuning, no extras for sale at this time but Wades or Rainier arms will have
H2's.
Bolt chipping comes from
Bad Headspacing, bad bolt carrier group or the timing is off.

First check the headspacing
if your bolt lugs are not locking in all the way from bad headspacing you could get this problem but I think you would have known sooner than 1500+ rounds later.
Your bolt carrier group could be a factory defect in strength but I'm
thinking Your bolt is bouncing back, unlocking just a little before you fire and slowly
taking small bites out of the lugs.
A heavier buffer will go into batt stronger and will help delay the bolt from
unlocking as fast after firing.
Just by looking at the pictures of your bolt, I would replace it or you may
have a boomer in your face some day.
You may want to check for dammage on the backside of the lugs of the barrel extension too.