View Full Version : Need help diagnosing problem.. bad bolt?
Hey guys,
Just went out to the farm to try out my freshly finished build.
I am having problems even firing a round once chambered in.
Once the round is chambered in, I pull the trigger, no boom.
*PLEASE NOTE: I HAVE USED THE FOLLOWING AMMO WITH ALL THE SAME RESULTS;
Hornady
Federal
Winchester
Eagle
Monarch
*
When I swapped BCG's with my buddy, the AR performed flawlessly (and did not leave any deformed brass like in the picture!)
As shown in picture 1, there is a strike mark on the round. Sometimes it is a decent looking strike mark and other times it is a very weak one.
Here is one of the many brass I had attempted to fire;
http://i.imgur.com/f5LGLYN.jpg
Here is a couple of steel cased poop ammo attempted to fire:
http://i.imgur.com/rTZ0SbW.jpg
*On the RARE occasion that a round actually fires, when I go to pick up the brass on the ground it has abnormal DENTS in the brass where the bullet was seated in the casing!* (See picture)
We're talking a 1/15th of a chance that one fired.. the casing looked un reloadable... like this:
http://i.imgur.com/hFHJfCv.jpg
The one on bottom is my BCG:
http://i.imgur.com/RJuhyG1.jpg
I know this is a great forum and I'm looking for enlightenment!
Any help would be greatly appreciated I would love to be able to get running again before the weekend!
Obscenejesster
05-23-13, 22:13
If you swapped BCG's and everything worked fine then I think you found the issue.
What kind of BCG are you using and did it work in a previous rifle?
Sent from my SGH-T999 using Tapatalk 2
bought it brand new..
what i'm trying to figure is what would cause such a problem like bad strikes and the brass being messed up is it the ejector/firing pin?
(going to use knowledge acquired when purchasing future bcg's)
Heavy Metal
05-23-13, 22:20
Have you tried cleaning the firing pin and channel?
Did you remove the shipping preservative and put REAL gun lube on it?
Obscenejesster
05-23-13, 22:25
Where did you buy the BCG and what kind is it?
Sent from my SGH-T999 using Tapatalk 2
Where is the channel located?
I lube and clean my guns religiously.
Every day they are fired they are cleaned and lubricated immediately following.
steyrman13
05-23-13, 22:28
Where is the channel located?
I lube and clean my guns religiously.
Every day they are fired they are cleaned and lubricated immediately following.
The tunnel the firing pin sits inside
Not all bolt carriers and bolts are created equal. It is very likely not your carrier as the firing pin travel is limited by the bolt itself. You either have a firing pin issue or a bolt issue. You can replace parts one at a time to check or get yourself a firing pin gauge. The other possible issue, I suppose, would be a headspace issue with your bolt.
Please tell us the make of your parts.
BTW, the dents in the case mouth are very likely to not be related to your other issues. However, they are entirely reloadable.
Bought it at a store.
Already told that they will fix the issue. But I am here to find out what can cause this and what to look for in a bad bolt or whatever issue this may be.
Unaware of the make.
Only know that it is carpenter 158
"properly" Staked, M inspected ect.
I can upload pictures if need be.
Please advise.
Thank you,
Darva
Remove the bolt. Make sure the bolt tail is clean. Check to make sure the shoulder on the firing pin is clean.
If you narrowed it down to the BCG then you need to get it closer. I would look at the firing pin (firing pin protrusion) and the bolt.
It is also possible that the carrier itself is out of spec. I would replace one piece at a time in the new carrier and narrow it down further.
TunaFisherman
05-23-13, 22:35
Bought it at a store.
Already told that they will fix the issue. But I am here to find out what can cause this and what to look for in a bad bolt or whatever issue this may be.
Unaware of the make.
Only know that it is carpenter 158
"properly" Staked, M inspected ect.
I can upload pictures if need be.
Please advise.
Thank you,
Darva
:confused: those questions are relevant. What make is the carrier? Knowing the brand could help finding your issue. You never asked the make of your BCG? Take IGs advice
What are the specs of the rifle & it's parts? Is it a factory model?
For whatever reason, your BCG is giving light strikes. There is a possibility that the carrier and/or firing pin is incompatible with the hammer. What causes the incompatibility I cannot recall as it's the tail end of a long day and my brain is mush.
The dented cases mouths are normal and they can be reloaded. The mouths will be rounded out in the re-sizing die
I will get the name of the make tomorrow as well as upload some more pictures tomorrow. It is getting late.
I trust the company that I purchased it from (that they wouldnt sell me crap.. lol) , I have done a lot of business with them and gotten them lots of business. They have already said they'll fix the problem and I know they will. Like I said.. using this thread as future reference in bcg endeavours. I'll have more information on the go tomorrow.
Thank you all for the insight I really appreciate it!
What are the specs of the rifle & it's parts? Is it a factory model?
BCM Upper
BCM 16" M4 SOCOM Barrel
BCM lo pro gas block
Del-Ton Lower
Spikes LPK
Spikes Heavy Buffer
Other:
Troy 11" Rails
CTR Stock
For whatever reason, your BCG is giving light strikes. There is a possibility that the carrier and/or firing pin is incompatible with the hammer. What causes the incompatibility I cannot recall as it's the tail end of a long day and my brain is mush.
Yeah man long day for me too. Even longer for my long anticipated rifle to not be working lol
TunaFisherman
05-23-13, 22:47
These guys will get it figured out. I would like to see pics of the Bolt, staking etc...just curious
These guys will get it figured out. I would like to see pics of the Bolt, staking etc...just curious
Thanks Tuna!
Pics to come tomorrow.
Have a good night everyone
uncle money bags
05-24-13, 00:47
So, where are the pics okie?
MiamiCracker
05-24-13, 07:16
Check the hammer spring to make sure it was not installed backwards.
HEY THERE! Uncle Money Bags!!! :laugh:
How ya doin man
Check the hammer spring to make sure it was not installed backwards.
I'm unable to check that at the moment but are there any ways to tell that it might have been installed backwards?
Here are the pics
http://i.imgur.com/PSrGLay.jpg
http://i.imgur.com/PNvJm7t.jpg
http://i.imgur.com/rph0kdI.jpg
http://i.imgur.com/7KALClY.jpg
http://i.imgur.com/OLwr6iI.jpg
MiamiCracker
05-24-13, 07:46
Google AR15 hammer spring and it should pop up. I had someone build my lower and the spring was installed backwards. I didn't find out till yesterday when my AR was having light strikes/FTF.
Littlelebowski
05-24-13, 07:46
If it functions properly with another BCG, it's not your hammer spring.
Now you need to do selective swapping with the known BCG. First try the good bolt in the bad BCG. Then, if that works try the bad firing pin in the aforementioned setup and so on. If the good bolt doesn't work in the bad BCG, that is a clue. You will quickly find the problem.
Good to know.
It's most likely going to take some time before they can get to me to swap the bcg so I will be hitting the range immediately after work to continue diagnosis.
Range report to follow!
Thanks everyone
uncle money bags
05-24-13, 10:24
HEY THERE! Uncle Money Bags!!! :laugh:
How ya doin man
Hey dude.
I have a hunch, try something out for me if you would.
With the bcg out of the weapon, close up the bolt in the locked position and push the firing pin from the rear causing it to protrude from the bolt face.
Does the pin protrude about one mm and is there a gap between the firing pin and the firing pin hole?
Im about 98% sure it wont be protruding far enough and that it is either the pin not being spec, or the bolt is holding it up.
You haven't shown the bolt removed from the carrier. As stated above, keep trying swaps if possible to determine which part is not working for you.
Simplest thing to try is a different firing pin, then the bolt only from the borrowed carrier group that functioned for you.
By all means clean the channel in the bolt itself to allow full travel for the firing pin, you are only .010" away from success!
Alright,
So I took apart the BCG.
There was a lot of build up from junk on the extractor.. which I have no idea how that happens because the damn thing has only successfully fired like 15 rounds.
ANYWAYS, I did a full field strip of it, did a very detailed clean and assembled it back together... took it to the range and NO LUCK.
I could not change out the minor parts with my buddy because he could not make it out to my range in time to go shoot today. We will most likely be going to the range tomorrow.
Here are the pics of everything:
(For you uncle, bolt pushed in with me NOT PUSHING the back end of the firing pin)
http://i.imgur.com/1atqaco.jpg
(For uncle, this is a pic of the bolt pushed in WITH ME PUSHING the back end of the firing pin)
http://i.imgur.com/PWokpAs.jpg
-------------------------
The following pics are of everything stripped;
http://i.imgur.com/Qj6bBD2.jpg
Extractor.
http://i.imgur.com/6trhtPZ.jpg
http://i.imgur.com/DhrxjPd.jpg
Inside of bolt after extractor removed:
http://i.imgur.com/CTyv6Xn.jpg
Without a firing pin protrusion gage you are spinning your wheels. You need to get another BCG and swap parts out.
You should also try that BCG in another upper (if you haven't already). Otherwise you will just keep chasing your tail without getting anywhere.
Is it just the photo or is the end of that bolt tail not square?
I thought it was an optical illusion. It's hard to say.
Is it just the photo or is the end of that bolt tail not square?
eternal24k
05-24-13, 22:17
As mentioned, swap part by part to narrow in on the problem. I would start with the firing pin and hope that's the problem. Then Swap the bolt, and then try the carrier with your bolt.
uncle money bags
05-24-13, 23:14
I asked him to check the protrusion in case it was obviously short. You dont need a gauge for that. Considering he didnt have another bcg at the moment to swap out parts, it is a reasonable thing to check.
Having said that, the advice to find another bcg to change out parts; one at a time, is your best bet.
The tail on that bolt does look funny. Is it angled?
If you cannot come up with another bcg quick let me know and i will hook you up for troubleshooting purposes.
Let me recap an incident in Tucson a couple of years back (2011?) at a Magpul course. One of the patrol sgts. from a local PD's started having malfunctions at around 2200 rounds (or so).
It was a Stag Arms 10.5" upper receiver group with Stag Arms BCG. I was racking my brains and couldn't figure it out, so I broke out my gage set. When I checked the firing pin protrusion and the firing pin hole both of them failed. We replaced the bolt and firing pin and it then ran flawlessly thereafter. So within a few thousand rounds the BCG failed.
Had I not brought my gages, we would have never found the issue and would have had to go through multiple steps to troubleshoot. There was visually no way to see this.
For reference the No Go (Min.) and Go (Max.) should be .028 and .036.
Problem solved.
Cleaned extractor sitting, replaced extractor and firing pin.
Works like a charm and I don't get a deformed brass ejection either!
Thank you everyone for your help!
Finally got to sight in my new scope this weekend!
It helps for those learning or perhaps with a similar issue down the road.
Very happy for you it was a simple fix, they usually are!
Now go out and wear it out. ;)
Those cases are all reloadable!
Hey guys,
Just went out to the farm to try out my freshly finished build.
I am having problems even firing a round once chambered in.
Once the round is chambered in, I pull the trigger, no boom.
*PLEASE NOTE: I HAVE USED THE FOLLOWING AMMO WITH ALL THE SAME RESULTS;
Hornady
Federal
Winchester
Eagle
Monarch
*
When I swapped BCG's with my buddy, the AR performed flawlessly (and did not leave any deformed brass like in the picture!)
As shown in picture 1, there is a strike mark on the round. Sometimes it is a decent looking strike mark and other times it is a very weak one.
Here is one of the many brass I had attempted to fire;
http://i.imgur.com/f5LGLYN.jpg
Here is a couple of steel cased poop ammo attempted to fire:
http://i.imgur.com/rTZ0SbW.jpg
*On the RARE occasion that a round actually fires, when I go to pick up the brass on the ground it has abnormal DENTS in the brass where the bullet was seated in the casing!* (See picture)
We're talking a 1/15th of a chance that one fired.. the casing looked un reloadable... like this:
http://i.imgur.com/hFHJfCv.jpg
The one on bottom is my BCG:
http://i.imgur.com/RJuhyG1.jpg
I know this is a great forum and I'm looking for enlightenment!
Any help would be greatly appreciated I would love to be able to get running again before the weekend!
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