BCG Jamming next bullet into feedramp

Cutting coils is a field repair. It still does not "fix" the problem.
Are the ejected cases sooty also?
Now you say it worked fine when it was clean. My mind tells me your cleaning and lube helped seal up something. Hmm
What might seal better with some oil on it?

1. I can't think of any buffer made for general sale that is to heavy for a a rifle built correctly and ammo to spec.
2. Springs rifle is approx 12.5-13" carbine is less than 11"
I forget the mil spec for the coils but less than 40 for carbine more than 40 for rifle.
3. Detail Strip your bolt make sure there is no shit in the gas port through the key into the bolt. Take your rings off and inspect them. Make sure your bolt body where the bolt rides is not shedding chrome or rotted.
Make sure you gas key is actually lining up with the gas tube.
Make sure you gas tube pin in the gas block is there.

The sooty cases could be from lack of sealing in the chamber or nature of the beast. Remember the ar pukes on itself

AE ammo should be OK... Its loaded to 3200fps or so. I prefer wolf gold over any AE ammo

Think like this the bolt is not getting enough energy or something is robbing energy from the bolt.

Do the ejected rounds ever slip off the extractor
 
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Are the ejected cases sooty also?
Now you say it worked fine when it was clean. My mind tells me your cleaning and lube helped seal up something. Hmm
What might seal better with some oil on it?

Do the ejected rounds ever slip off the extractor

Ejected case we're sooty, yes.
Rounds Never slipped off the ejector.
I thoroughly cleaned the bolt and inspected before this trip. All looked normal.
Made sure to have all the ports on the rings in different directions.

When I cleaned it, I ran a clean dry pipe cleaner through both gas tube in the chamber and the bolt looking for any debris.
 
Sooty cases are generally low powered cartridges not expanding enough or loose/excessive chamber or headspace
 
Just noticed wear on the top and one side of the charging handle.. Is that normal? Didn't notice it before.
 

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Checked the gas key for leaks. All good there.
Checked the gas block to see if the pin on the bottom holding it to the barrel came loose. Took a couple of whacks at it through the hand guard, didn't budge.
Looks like good there too.

Nothing I can do now until I go to the range and swap the bcg or lower from another gun.
 
What AE ammo did you use was it 223 or M193 ?
Did you build this upper? If not are you sure your gas block is not adjustatable?
 
I just loaded a couple 20 rnders of the ae 223. I was using. And then a single 20 rnd of Wolf Gold 223.

If I get it malfunction like it has with the ae. I'll put in the Wolf magazine and see if there is any change.
 
I just realized the buffer tube I mentioned above is in the Colt..
I can't find any receipts for the buffer tube in this gun.

I'm going to compare the two tonight. Measure the weight of the buffers and the length of the springs.
Who knows, maybe I am using a full size spring with that carbine gas tube.
 
I think I'm on to something..

Was curious about the buffer and spring I used because I can't find the receipt of it.
And noticed that the gas tube is carbine length..

The buffer I bought for the colt is carbine length. So why not compare them
The buffers are almost identical in weight. 2.965oz and 2.94oz
But the colt is 10" spring.
And the rifle with the problem is 11.5"
I'm using a standard buffer spring in a carbine gas tube.

Would explain the extra resistance and the shirt stroke of the bolt..
 
TECHNICAL MANUAL
ARMY NO. 9-1005-319-23&P
AIR FORCE TO 11W3-5-5-42

RIFLE: 11 3/4 Inches (29 85 cm)
minimum to 13 1./2 inches (34 29 cm)
maximum

CARBINE: 10 1/16 inches (25.56 cm)
minimum to 11 1/4 inches (28.58 cm)
maximum

Springs shorten with use. Your 11.5" is either a really worn rifle springs, or a new (possibly out of spec) carbine spring. There is not a standard on number of coils due to different spring meterials and manufacturers.

I think you have a confusion or misnaming of parts. The gas tube (can be rifle length, carbine length or midlength) are located over the barrel and deliver gas from the gas port/gas block through the upper receiver and to the bolt's gas key.

The buffer tube, also refered to as a receiver extension, are available in carbine and rifle, and is threaded into the rear of the lower receiver and house the buffer and buffer spring.
 
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I just realized the buffer tube I mentioned above is in the Colt..
I can't find any receipts for the buffer tube in this gun.

I'm going to compare the two tonight. Measure the weight of the buffers and the length of the springs.
Who knows, maybe I am using a full size spring with that carbine gas tube.
Time for pictures:
Now I'm going on memory here and talking "mil spec"
Rifle buffer spring will have 40 plus coils and carbine spring will have less than 40.
Springs if I recall rifle more than 12" is good Carbine is 10" that's "serviceable"
New Rifle spring is closer to 13" New Carbine is 10.5"
Confusing parts from one rifle to the next can really throw you off. Hope you found it. If that AE ammo is as weak as some of the stuff I have gone through it adds to the problem.
 
I've put literally thousands of rounds through some of mine and just a squirt of oil to keep running smooth. There is a gas issue that is borderline fail on your upper if it does the same thing on a different lower.
 
Springs shorten with use. Your 11.5" is either a really worn rifle springs, or a new (possibly out of spec) carbine spring. There is not a standard on number of coils due to different spring meterials and manufacturers.

I think you have a confusion or misnaming of parts. The gas tube (can be rifle length, carbine length or midlength) are located over the barrel and deliver gas from the gas port/gas block through the upper receiver and to the bolt's gas key.

The buffer tube, also refered to as a receiver extension, are available in carbine and rifle, and is threaded into the rear of the lower receiver and house the buffer and buffer spring.

I think I had some typos in there and some ands were swapped with in.

Pretty sure I have a carbine length gas tube. A full size 11.5" buffer spring, that should be carbine length of 10"..
 

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Where are your casings ejecting? 1 o’clock is over gassed or the bcg’s extrector is filthy and the bcg needs to be completely torn down for cleaning. 3 o’clock to 4 o’clock is perfect. Beyond that, you are undergassed.

The first thing you should have done would be to swap out the bcg with the one you know works. It will tell you a lot.
 
Where are your casings ejecting? 1 o’clock is over gassed or the bcg’s extrector is filthy and the bcg needs to be completely torn down for cleaning. 3 o’clock to 4 o’clock is perfect. Beyond that, you are undergassed.

Check out the videos in the posts above.
In the video they're being thrown back to 4.

I detail cleaned it before this trip to the range. And I'm swapping lowers and bcg on next trip to the range.

Didn't try it last time because it was working at first. Starting failing at the very end when I was about to leave.
 
If you have another gun, try swapping springs/parts one at a time and look for improvement. Buffer, spring, bolt etc.

And also if you have not already put compressed air through the barrel/gas block and make sure it gets to the receiver and vice versa. Sounds like the gas isn't right.
 
I think I had some typos in there and some ands were swapped with in.
I

Pretty sure I have a carbine length gas tube. A full size 11.5" buffer spring, that should be carbine length of 10"..
11" should be fine. Heck won't shock me if mil spec acceptance is just a touch over 11" and less than 10" for reject
Again need better pics of what you have. Something simple I think is giggling as we/you over look it.
I say return platform to how it was and try some better ammo. Then if still problems switch lowers and test each rifle.
2 things will happen. Either the working rifle will fail with the suspect lower or the suspect upper will fail with the known good lower. If both weapons fail you know you have problems with the upper and lower.
Also check gas port hole for any chrome flashing.

Im going to fall back on your " after cleaning it worked for a while" There is not much where cleaning and oil will help a gas issue. Other than bolt and rings.

I say do this
1. bring rifle to range. shoot it as it is in its failing condition. once the failure serfaces regulary put 1 drop of oil in each hole on the holes on the bolt with the bolt pulled back. if your rilfe magically functions again your bolt/BCG/rings are NFG- return bolt to vendor and ask for a replacement
 
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The things I do for you people.. Braved the biting cold this morning and hit the range.
21 degrees and with the wind chill i think it was -200.

I ran a 30 round magazine through it and it seemed to go off without a hitch. Strange.
Decided to shoot the Colt. Then went back to the problem rifle with a fresh magazine, few rounds later, and bingo, got some missed loads, then some FtF jams.
Here are pics of some of those bullets. Scrape on one side, dent on the other. And a stuck round.
Then I put in a magazine of Wolf Gold and it shot no problem. Went back to original ammo and back to the jams.
So it obviously doesn't like the Fed AE 223 Rem 55g FMJ

Now I can start swapping parts. Swapped lowers. Both ran fine.
Swapped the Buffer tube springs in the lowers and continued to run fine.

Swapped everything back and then FtF jams on the problem gun.

So I just swapped the buffer and spring again and both continue to work great.
Long story short I believe it was the longer spring and weak ammo causing the problems.
(The Colt upper shot the longer spring without a hick-up.) So swapping buffer and springs inside each lower is my solution for the time being.
Going to leave it dirty and run it a lot more and try and get a lot more rounds through it. Only about 130 rounds today. Atleast until I notice any more hick-ups and then I'll see what swapping BCG's does to it.
 

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Those bullets are fine.:confused:.
I think your spring is fine its the shitty AE ammo. Its right there with UMC for shit ammo. I rather run steel and actually liked the old norinco 223 ammo I used to have over the AE or Remington other than some high velocity yellow and green box hunting rounds I had.
Technical manual
https://www.google.com/url?sa=t&sou...FjABegQICRAB&usg=AOvVaw19Qbf_OG6-wilCwNjOJmfF

Carbine buffer spring
CARBINE ONLY: Free length should be 10 1/16 in. (25.56 cm) minimum to 11 1/4 in. (28.58 cm) maximum

So your problem is most likely just ammo.
Your other rifle might run better because of a different bolt design/weight or worn buffer spring.
Also buffer weight might be different.

You never really know what the ammo manufactures are running. The powder choice might not have enough gas pressure and gas volume to function 100%
Although my mil spec A2 will run a low charge of H4895 with cast loads just a touch over 2000fps.
Its all fun
 
Those bullets are fine.:confused:.
Carbine buffer spring
CARBINE ONLY: Free length should be 10 1/16 in. (25.56 cm) minimum to 11 1/4 in. (28.58 cm) maximum

So your problem is most likely just ammo.
Your other rifle might run better because of a different bolt design/weight or worn buffer spring.
Also buffer weight might be different.

Don't forget.. I was also using a spring that was 11.5" which was above the Max length in the specs above.. Switching to the 10" was the difference.. Along with the better ammo.
I already bought the $7 10" replacement buffer spring for it.
We'll see how it goes the next few times I go out with that one and put a few hundred rounds through it.
 
Don't forget.. I was also using a spring that was 11.5" which was above the Max length in the specs above.. Switching to the 10" was the difference.. Along with the better ammo.
I already bought the $7 10" replacement buffer spring for it.
We'll see how it goes the next few times I go out with that one and put a few hundred rounds through it.
Humor me and count the coils in the 11.5" spring please. Just want to know
 
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