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9/17/2020 5:59:48 PM
Posted: 4/24/2014 12:59:36 PM EDT
Went to the range today (first time in months).  Took the AR out, inserted a mag, pulled the charging handle back and the first round got hung up and jammed (FTF).  Took mag out, re-inserted, pulled charging handle and again FTF.  Finally after several attempts, I got one to go in.  Started firing, no issues, every round fed in.

Inserted new mag and again, FTF on first round.  Thought maybe I was riding the bolt forward, so I inserted a new mag on an open bolt, hit the release and had a FTF.  Did this a few times, but then the issue resolved itself on the open bolt.  Again, while firing, no problems, no failures of any kind.

Inserted new mag, on a closed bolt, pull charging handle and had a FTF every time.  It was a little dry, forgot to bring lube with me.  Yet again, no malfunctions of any kind while firing.  I am perplexed.  I have never had a failure of any kind before this in the several thousands of rounds I have shot through this gun.

I did put a new FF tube on recently and this is the first time firing it since the change.  Is head space off?  Is it just dry?  What says ARFCOM?


Stag Arms upper
Denny's full auto bolt/carrier
Link Posted: 4/24/2014 1:03:50 PM EDT
Hanging up on the feed ramps?  Post pics if you can.

Likely the barrel extension wasn't tumbled smooth to deburr it after the feed ramps were cut, so you've got jagged, machined edges snagging the rounds.  It will wear in over time, or you can take a small file or some sandpaper on a dowel rod to smooth out the rough edges right now.
Link Posted: 4/24/2014 1:07:39 PM EDT
Originally Posted By Gabriel11808:
Went to the range today (first time in months).  Took the AR out, inserted a mag, pulled the charging handle back and the first round got hung up and jammed (FTF).  Took mag out, re-inserted, pulled charging handle and again FTF.  Finally after several attempts, I got one to go in.  Started firing, no issues, every round fed in.

Inserted new mag and again, FTF on first round.  Thought maybe I was riding the bolt forward, so I inserted a new mag on an open bolt, hit the release and had a FTF.  Did this a few times, but then the issue resolved itself on the open bolt.  Again, while firing, no problems, no failures of any kind.

Inserted new mag, on a closed bolt, pull charging handle and had a FTF every time.  It was a little dry, forgot to bring lube with me.  Yet again, no malfunctions of any kind while firing.  I am perplexed.  I have never had a failure of any kind before this in the several thousands of rounds I have shot through this gun.

I did put a new FF tube on recently and this is the first time firing it since the change.  Is head space off?  Is it just dry?  What says ARFCOM?


Stag Arms upper
Denny's full auto bolt/carrier
View Quote


Should really be in the troubleshooting forum - however - perhaps your gas tube is slightly "off center" if you re-assembled it yourself?  

If it's slightly off - the drag of the gas tube might be a "little much" for simple spring tension to overcome during the initial loading, but not so "bad off" that the full pressure of the firing cycle doesn't just "jam itself" into battery.  

Doubt it would be a headspace issue - though I'd be curious why, if you suspected it might be a headspacing issue, why you would keep firing it?  

Lube would probably help...

If it is the gas tube - the best option would be to simply re-assemble it and make sure you get the tube properly aligned.  

An easy way to check and see if there are any issues with the gas tube alignment is to remove the upper, and just try to drop the BCG in - if the gas tube is out of alignment and dragging on the carrier key, then it will often fail to go fully into battery.  

~Augee
Link Posted: 4/24/2014 1:29:16 PM EDT
[Last Edit: 4/24/2014 1:33:25 PM EDT by kiddsf]
Originally Posted By Gabriel11808:
Went to the range today (first time in months).  Took the AR out, inserted a mag, pulled the charging handle back and the first round got hung up and jammed (FTF).  Took mag out, re-inserted, pulled charging handle and again FTF.  Finally after several attempts, I got one to go in.  Started firing, no issues, every round fed in.

Inserted new mag and again, FTF on first round.  Thought maybe I was riding the bolt forward, so I inserted a new mag on an open bolt, hit the release and had a FTF.  Did this a few times, but then the issue resolved itself on the open bolt.  Again, while firing, no problems, no failures of any kind.

Inserted new mag, on a closed bolt, pull charging handle and had a FTF every time.  It was a little dry, forgot to bring lube with me.  Yet again, no malfunctions of any kind while firing.  I am perplexed.  I have never had a failure of any kind before this in the several thousands of rounds I have shot through this gun.

I did put a new FF tube on recently and this is the first time firing it since the change.  Is head space off?  Is it just dry?  What says ARFCOM?


Stag Arms upper
Denny's full auto bolt/carrier
View Quote


Fail to Feed only when chambering the first round from magazine?
Probably just too dry, lube it next time you head to range.
You can try manual cycling at home once you take out the firing pin.

Another possibility could be due to the magazine.
Perhaps the spring is too strong causing the first round from a fully loaded mag to have too much pressure on the feed lips.
What mag were you using?
I had a aluminum 20rd mag with very slow(not smooth and fast) feeding on the first round due to too much pressure upwards on the first round from the spring.

You mentioned the rifle never give any trouble even after thousands of rounds fired, so I doubt it has to do with the gun's specs.
Link Posted: 4/24/2014 1:38:29 PM EDT
I watched a guy at the range fight this.  He was following the CH.

Let it fly!
Link Posted: 4/24/2014 1:48:50 PM EDT
Next time at the range chamber a 55 gr. round by riding the charging handle forward to see if the bullet is catching between the top corner edges of the feed ramp's barrel extension lugs. A barrel extension blueprint shows that the corners of these lugs that each feed ramp is between are supposed to have a radius, though from the many pictures of various barrel extensions that can be viewed from Google Images shows that many do not have this radius added.

Link Posted: 4/24/2014 1:51:39 PM EDT
[Last Edit: 4/24/2014 1:52:57 PM EDT by panther308]
Since I found this topic I have to ask I was given some GI Mags with green followers and they feed okay until you get down to the last 3-4 cartridges and then they get jammed up and I am wondering the cause like worn spring ? I believe the mags are Center Industries and have an 04 stamped on the bottom
Link Posted: 4/24/2014 1:55:27 PM EDT
Yes, I would say the springs are shot...
Link Posted: 4/24/2014 1:59:27 PM EDT
[Last Edit: 4/24/2014 2:00:08 PM EDT by AR-4C]
As it is mentioned in five posts above this one; it is not best to charge an AR without a firing pin in place. The reason being is without a firing pin in place there is nothing to keep the cam pin from spinning out of alignment within the half-moon cutout of the upper receiver. If the cam pin gets out of alignment here it locks up the bolt carrier group due to the cam pin is no longer lined up with the track the cam pin shares with the charging handle.
Link Posted: 4/24/2014 2:13:59 PM EDT
Rounds are hanging up on feed ramp.  But the gun already has several thousand rounds through it with out any issues before today.  So I doubt there any burrs.  

I used mainly Tula steel case today and a little Federal brass case.  First time I've used Tula before, though I have shot Wolf with no issues.  I do not remember if the brass hung up as well or not.

I was using Pmags and 1 Camega mag. It did it on all mags, not just one.  No issues with these mags before either.
Link Posted: 4/24/2014 2:44:34 PM EDT
did you shoot any brass through it since the issue? You should determine  what ammo were you using during the issue, or if both had issues. I was thinking you may have gotten some out of spec Tula.
Link Posted: 4/24/2014 2:57:40 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By shootertim:
did you shoot any brass through it since the issue? You should determine  what ammo were you using during the issue, or if both had issues. I was thinking you may have gotten some out of spec Tula.
View Quote




I'm going to load one of each kind of ammo (Wolf steel, Tula steel and Federal brass) in two different mags (1 Cammega, 1 Pmag) and see which one(s) I have problems with, while loading with the charging handle.   BRB!  Update to follow.
Link Posted: 4/24/2014 3:06:49 PM EDT
Originally Posted By Gabriel11808:
Went to the range today (first time in months).  Took the AR out, inserted a mag, pulled the charging handle back and the first round got hung up and jammed (FTF).  Took mag out, re-inserted, pulled charging handle and again FTF.  Finally after several attempts, I got one to go in.  Started firing, no issues, every round fed in.

Inserted new mag and again, FTF on first round.  Thought maybe I was riding the bolt forward, so I inserted a new mag on an open bolt, hit the release and had a FTF.  Did this a few times, but then the issue resolved itself on the open bolt.  Again, while firing, no problems, no failures of any kind.

Inserted new mag, on a closed bolt, pull charging handle and had a FTF every time.  It was a little dry, forgot to bring lube with me.  Yet again, no malfunctions of any kind while firing.  I am perplexed.  I have never had a failure of any kind before this in the several thousands of rounds I have shot through this gun.

I did put a new FF tube on recently and this is the first time firing it since the change.  Is head space off?  Is it just dry?  What says ARFCOM?


Stag Arms upper
Denny's full auto bolt/carrier
View Quote

Link Posted: 4/24/2014 3:28:47 PM EDT
Very strange.  I loaded 3 mags.  1 Cammega, 1 Pmag and 1 USGI mag I modified to hold 5 rounds for hunting (has a wood block inserted). I loaded all mags the same, 1 Federal brass, 1 Wolf steel, 1 Tula steel (Tula was on top in mag).  No lube added.

First up USGI modifed- Tula FTF.  I wanted to be sure I was really letting the bolt fly, so reloaded the Tula into the mag and tried again.  It FTF.   Wolf fed and Federal fed.

Next, Pmag.  All three fed fine.

Last, Cammega mag (the one I noticed I had trouble with first at the range).  All three fed fine.


Loaded the USGI modified mag again and all three fed fine.  But was noticeably "sluggish" compared to the other 2 mags. Could my buffer tube spring need to be replaced?  Could it be to weak to over come the pressure of a full mag?
Link Posted: 4/24/2014 3:37:58 PM EDT
[Last Edit: 4/24/2014 5:38:57 PM EDT by Gabriel11808]
Reloaded the USGI modified mag again, with 5 rounds of Tula. A couple FTF.  Loaded the Cammega mag with 5 Tula and 3 brass, no FTF.  Reloaded USGI mag again, a couple FTF.  Strange.  
Link Posted: 4/24/2014 7:11:55 PM EDT
[Last Edit: 4/24/2014 7:12:51 PM EDT by Spearjunkie]
So you are trying to figure what the feed issue is and have not cleaned and lubed it?
Link Posted: 4/24/2014 7:18:22 PM EDT
If your AR uses a carbine length action spring instead of a rifle length spring; a carbine spring's free length (not compressed) should measure from a minimum length of 10-1/16" to a maximum length of 11-1/4". Also, about the feed ramps it's not burrs that holds up rounds, but rather the shape. Comparing the before and after pictures below, and notice the shape of the four top corner edges of the lugs the feed ramps are between.

Before:


After:
Link Posted: 4/25/2014 6:52:09 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Spearjunkie:
So you are trying to figure what the feed issue is and have not cleaned and lubed it?
View Quote



If the problem was not enough lube or to dirty, would it not jam during firing as well?  Since the jam only occured while trying to manually charge the first round in the weapon, from a full mag and only with Tula, lends me to believe it is not a lube problem.  I am starting to believe that my buffer tube spring/action spring is getting worn out and can not overcome the tension from a fully loaded mag and something with the Tula ammo contributes to the FTF.  

How long/many rounds should the average action spring be good for?  I have about 4,000 rounds through the gun, give or take a couple hundred.  I will take it out today and measure it.
Link Posted: 4/25/2014 7:06:42 AM EDT
When you are troubleshooting, you need to eliminate as many variables as possible to pin point the problem.
If the rifle is not clean and lubed, you have no idea why it's not functioning properly.
You might have a piece of gunk in the FCG.

On recoil the buffer bumper impacts the back of the receiver extension and compresses, then springs back.
That doesn't happen when manually cycling.

Take 30 minutes and clean the thing, then get back to us.
Link Posted: 4/25/2014 8:14:38 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gabriel11808:



If the problem was not enough lube or to dirty, would it not jam during firing as well?  Since the jam only occured while trying to manually charge the first round in the weapon, from a full mag and only with Tula, lends me to believe it is not a lube problem.  I am starting to believe that my buffer tube spring/action spring is getting worn out and can not overcome the tension from a fully loaded mag and something with the Tula ammo contributes to the FTF.  

How long/many rounds should the average action spring be good for?  I have about 4,000 rounds through the gun, give or take a couple hundred.  I will take it out today and measure it.
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Originally Posted By Gabriel11808:
Originally Posted By Spearjunkie:
So you are trying to figure what the feed issue is and have not cleaned and lubed it?



If the problem was not enough lube or to dirty, would it not jam during firing as well?  Since the jam only occured while trying to manually charge the first round in the weapon, from a full mag and only with Tula, lends me to believe it is not a lube problem.  I am starting to believe that my buffer tube spring/action spring is getting worn out and can not overcome the tension from a fully loaded mag and something with the Tula ammo contributes to the FTF.  

How long/many rounds should the average action spring be good for?  I have about 4,000 rounds through the gun, give or take a couple hundred.  I will take it out today and measure it.


Actually lube very well IS the problem.  If the recoil spring has that many cycles on it, plus trying to overcome a dry condition, failure to go into battery would make sense.  Once fired, however, the spring gains more energy as the cycling typically pushes the reciprocating parts further into the buffer tube than you typically do charging it.  

As others have said, eliminate variables and leave only posibilities.
Link Posted: 4/25/2014 10:32:05 AM EDT
[Last Edit: 4/25/2014 10:32:47 AM EDT by kiddsf]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gabriel11808:



If the problem was not enough lube or to dirty, would it not jam during firing as well?  Since the jam only occured while trying to manually charge the first round in the weapon, from a full mag and only with Tula, lends me to believe it is not a lube problem.  I am starting to believe that my buffer tube spring/action spring is getting worn out and can not overcome the tension from a fully loaded mag and something with the Tula ammo contributes to the FTF.  

How long/many rounds should the average action spring be good for?  I have about 4,000 rounds through the gun, give or take a couple hundred.  I will take it out today and measure it.
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Originally Posted By Gabriel11808:
Originally Posted By Spearjunkie:
So you are trying to figure what the feed issue is and have not cleaned and lubed it?



If the problem was not enough lube or to dirty, would it not jam during firing as well?  Since the jam only occured while trying to manually charge the first round in the weapon, from a full mag and only with Tula, lends me to believe it is not a lube problem.  I am starting to believe that my buffer tube spring/action spring is getting worn out and can not overcome the tension from a fully loaded mag and something with the Tula ammo contributes to the FTF.  

How long/many rounds should the average action spring be good for?  I have about 4,000 rounds through the gun, give or take a couple hundred.  I will take it out today and measure it.


My friend's Colt 6920 have over 5000 rounds through it and my old Spike's Carbine length rifle have over 3500rds, and both still functions perfectly with original parts.
Pretty sure the spring will last more than 4000rds, but it won't hurt to swap it out.
Link Posted: 4/25/2014 11:09:01 AM EDT
Is it possible the USGI mag is just a bad mag and that's why you're getting failures to feed with only it?
Link Posted: 4/25/2014 2:28:10 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Krylancelo:
Is it possible the USGI mag is just a bad mag and that's why you're getting failures to feed with only it?
View Quote



It has happened with other mags on the range as well and only while manually cycling the bolt.  

I cleaned and lubed the hell out if it today, but I won't get a chance to go shoot again for a couple weeks.  Maybe it was simple as being to dry.  I measured the action spring when I had it apart, just over 10.5 inches.  I will manually cycle some rounds tonight when I get home.
Link Posted: 4/25/2014 4:20:22 PM EDT
Apparently it was nothing more than being to dry.  I loaded the 40rd Pmags in, cycled several Federal brass case through it, no issues.  I was just perplexed why it would only jam when manually cycling the bolt, but not firing and only with Tula ammo.  Problem solved, I'm a dumb ass.  Thanks for the help, carry on, nothing to see here.


I usually keep it very wet, so that's why I've never experienced the problem before.  
Link Posted: 4/25/2014 4:59:47 PM EDT
[Last Edit: 4/25/2014 5:01:42 PM EDT by kiddsf]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gabriel11808:
Apparently it was nothing more than being to dry.  I loaded the 40rd Pmags in, cycled several Federal brass case through it, no issues.  I was just perplexed why it would only jam when manually cycling the bolt, but not firing and only with Tula ammo.  Problem solved, I'm a dumb ass.  Thanks for the help, carry on, nothing to see here.


I usually keep it very wet, so that's why I've never experienced the problem before.  
View Quote


Good to know it was a lack of lube issue.
Just FYI, when charging with hand, even my Arsenal SLR-107(when dirtied with 1200+rds uncleaned/ no lube) will hang up on a fully loaded mag with polymer coated steel case ammo(Wolf, Tula).
The case treatment or the material of the case itself can cause hang up.
Link Posted: 4/25/2014 5:55:09 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By kiddsf:


Good to know it was a lack of lube issue.
Just FYI, when charging with hand, even my Arsenal SLR-107(when dirtied with 1200+rds uncleaned/ no lube) will hang up on a fully loaded mag with polymer coated steel case ammo(Wolf, Tula).
The case treatment or the material of the case itself can cause hang up.
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Originally Posted By kiddsf:
Originally Posted By Gabriel11808:
Apparently it was nothing more than being to dry.  I loaded the 40rd Pmags in, cycled several Federal brass case through it, no issues.  I was just perplexed why it would only jam when manually cycling the bolt, but not firing and only with Tula ammo.  Problem solved, I'm a dumb ass.  Thanks for the help, carry on, nothing to see here.


I usually keep it very wet, so that's why I've never experienced the problem before.  


Good to know it was a lack of lube issue.
Just FYI, when charging with hand, even my Arsenal SLR-107(when dirtied with 1200+rds uncleaned/ no lube) will hang up on a fully loaded mag with polymer coated steel case ammo(Wolf, Tula).
The case treatment or the material of the case itself can cause hang up.


Yeah, I can't remember how many rounds I've shot through it since the last cleaning.  700-800, maybe more.  I would just usually spray some lube before and after each range session and call it good.  I've been working full time and going to school full time on top of taking care of my 3 kids, so it sat in the safe all winter untouched.  Last time I shot was last July, so she was pretty dry.  When I shoot, I run her pretty hard too.  I forgot to take some lube with me this last time.  I was just confused by the pattern of FTFs.  Oh well, live and learn.
Link Posted: 4/25/2014 8:54:21 PM EDT
How many rounds with that action spring? If over 5k or so, swap in a new one. Cheap, and oftentimes fixes some of these mystery problems.
Also check the alignment of the gas tube as mentioned. It could be just a little off.
A little more lube.
Try pulling the charging handle all the way to the rear and letting go instead of hitting the bolt release. So e times that extra quarter inch can make a difference, especially if the action spring is a little weak.
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