AR15.Com Archives
 New AR15 - Failure to feed
radian23  [Member]
12/25/2008 6:25:40 PM
I took my ar15 to the range for the first time and ran into problems. I was using remington UMC 55 grain and was getting a ton of fail to feeds. I was getting times when the gun wouldn't strip a round from the magazine, other times where it would just gouge side of the casing and other times where it would would strip the round but not feed it into the chamber (Wedged in). I tried using a PMAG and a Brownells magazine. I also tried using a heavy buffer and a carbine buffer. With all of these combinations I was still getting fail to feeds.

I was able to fire about 5 rounds of PMC Bronze 55 grain FMJ-BT. I found that my gun would cycle these but would not lock back the slide when the magazine was empty.

I also noticed the gun shot low and to the far right at a distance of 10 yards. I would have shot at a longer distance but I was dealing with all the fail to feeds. Is this normal at such a close distance?

Any recommendations? These are the specifications of my problem child:

Essential Arms Low Shelf Lower Receiver with Tough Coat
14.5 CMMG mid-length, chrome lined, government profile, 1/7 twist, 5.56 NATO
Phantom Flash Suppressor
CMT M4 upper receiver
Young National Match M16 Chrome Bolt Group Assembly
Vltor Emod Stock
Magpul MOE Grip
RRA Lower Receiver Parts Kit
Matech BUIS
Rock River Arms Forged Charging Handle
Standard Midlength Handguards
5 Position Mil Spec Receiver Extension Kit with Heavy Buffer
Lionhead Rabbit (Buster)

Thanks in advance

badazzar15  [Industry Partner]
12/25/2008 6:33:10 PM
Sounds as if it could be short stroken. What kind of gas block or front site is on it? Is it tight? Is your carrier key tight?
radian23  [Member]
12/25/2008 6:50:33 PM
Originally Posted By badazzar15:
Sounds as if it could be short stroken. What kind of gas block or front site is on it? Is it tight? Is your carrier key tight?


My gas block is a F marked front sight. Tried wiggling it around and got no movement. Checked the carrier key. It is staked and tight. Is there a way to see if the gas block is in the correct position? The upper was built by somebody else so I'm not sure how they aligned it.
ZekeMenuar  [Team Member]
12/25/2008 7:15:03 PM
New gun and short stroking? Not enough lube maybe?

I'd try it again with the BCG and upper receiver slopped in CLP. If you have some XM193 I'd try that too.
SuperiorBarrels  [Industry Partner]
12/25/2008 7:18:43 PM
Inspect the buffer tube and the bolt carrier for drag marks or ridges.

Inspect all magazines used to see if the lips are dragging on the bolt carrier.

Inspect the gas tube where it inserts into the FSB for excessive blow-by.

Post photos if you can.
ftldrben  [Member]
12/25/2008 7:43:51 PM
+1

And the REASON you want to start with an AR from a major brand and customize it from there UNLESS your an armorer.
radian23  [Member]
12/25/2008 7:51:40 PM
Originally Posted By ftldrben:
+1

And the REASON you want to start with an AR from a major brand and customize it from there UNLESS your an armorer.


Thanks. Answers my question I built an AK47 last summer from a parts kit and a flat receiver. I felt this would be fairly simple compared to the AK. I'm asking this question because there are experienced people on this forum that seem willing to help one another.

On the topic of buying a major brand and customizing it:
I find it enjoyable to work with my hands. Trying to figure how stuff works and putting it together is something I love to do. When things need to be done on the car I do it myself, when stuff needs to be fixed around the house I do it myself etc. Some people prefer to just do thing themselves.
SuperiorBarrels  [Industry Partner]
12/25/2008 8:08:04 PM
Originally Posted By radian23:
I built an AK47 last summer from a parts kit and a flat receiver.
FLAT RECEIVER! That was good work.

I am having issues with pressing rivets for my trigger guard on my Yugo M-95 set (5.56mm)! I don't have a jig, and its a bitch.
radian23  [Member]
12/25/2008 8:14:50 PM
Originally Posted By SuperiorBarrels:
Originally Posted By radian23:
I built an AK47 last summer from a parts kit and a flat receiver.
FLAT RECEIVER! That was good work.

I am having issues with pressing rivets for my trigger guard on my Yugo M-95 set (5.56mm)! I don't have a jig, and its a bitch.


My uncles a machinist and was nice enough to make a jig. I don't have any experience with Yugos but for my Romy-G I made a plate to support the trigger guard and created dimples for the rivets. For the inside of the receiver I used a railroad stake and angle grinded it to fit in the receiver to smash the rivets. It was ghetto but hey it worked
badazzar15  [Industry Partner]
12/25/2008 8:16:10 PM
Originally Posted By SuperiorBarrels:
Inspect the buffer tube and the bolt carrier for drag marks or ridges.

Inspect all magazines used to see if the lips are dragging on the bolt carrier.

Inspect the gas tube where it inserts into the FSB for excessive blow-by.

Post photos if you can.


+1
radian23  [Member]
12/25/2008 8:22:53 PM
I know I'm not supposed to ride the carrier down but when I do the tip of the bullet gets stuck in the feed ramps. Should they be able to freely slide in if I ride the carrier? If I let the carrier close on its own and inspect the cartridges afterwards I get small scratches on the bullets. I checked magazine feedlips and didn't notice anything. Bolt carrier doesn't have any abnormal marks. Buffer looks fine.
radian23  [Member]
12/25/2008 8:29:04 PM
Originally Posted By SuperiorBarrels:

Inspect the gas tube where it inserts into the FSB for excessive blow-by.



I looked at the gas tube where it inserts into the FSB and it seems to be solid with no play. How do I check for excessive blow-by?
badazzar15  [Industry Partner]
12/25/2008 8:33:37 PM
Originally Posted By radian23:
Originally Posted By SuperiorBarrels:

Inspect the gas tube where it inserts into the FSB for excessive blow-by.



I looked at the gas tube where it inserts into the FSB and it seems to be solid with no play. How do I check for excessive blow-by?



Do you see any carbon build up on it where its installed into the FSB?
radian23  [Member]
12/25/2008 8:51:19 PM
Originally Posted By badazzar15:
Originally Posted By radian23:
Originally Posted By SuperiorBarrels:

Inspect the gas tube where it inserts into the FSB for excessive blow-by.



I looked at the gas tube where it inserts into the FSB and it seems to be solid with no play. How do I check for excessive blow-by?



Do you see any carbon build up on it where its installed into the FSB?


From what I can see there is no carbon buildup in that location. Its a little hard to see because the part the holds the handguards in butts right up against the FSB.
SuperiorBarrels  [Industry Partner]
12/25/2008 9:25:27 PM
Originally Posted By radian23:
I know I'm not supposed to ride the carrier down but when I do the tip of the bullet gets stuck in the feed ramps. Should they be able to freely slide in if I ride the carrier? If I let the carrier close on its own and inspect the cartridges afterwards I get small scratches on the bullets. I checked magazine feedlips and didn't notice anything. Bolt carrier doesn't have any abnormal marks. Buffer looks fine.
I have uppers that feed bullets and don't feed bullets when riding the carrier. All of them function without issue while firing. I would not worry about the scratches; it is just the way the AR15/M16 rifle works.

I am still wondering what is causing issues.

Lubricated your bolt carrier rails, inside the upper receiver, and piston rings/cylinder. Please use a lubricant WITHOUT Teflon. I use Mobile 1.

Give a standard weight buffer and standard buffer spring a try and see what happens.
radian23  [Member]
12/25/2008 9:54:50 PM
Originally Posted By SuperiorBarrels:
Originally Posted By radian23:
I know I'm not supposed to ride the carrier down but when I do the tip of the bullet gets stuck in the feed ramps. Should they be able to freely slide in if I ride the carrier? If I let the carrier close on its own and inspect the cartridges afterwards I get small scratches on the bullets. I checked magazine feedlips and didn't notice anything. Bolt carrier doesn't have any abnormal marks. Buffer looks fine.
I have uppers that feed bullets and don't feed bullets when riding the carrier. All of them function without issue while firing. I would not worry about the scratches; it is just the way the AR15/M16 rifle works.

I am still wondering what is causing issues.

Lubricated your bolt carrier rails, inside the upper receiver, and piston rings/cylinder. Please use a lubricant WITHOUT Teflon. I use Mobile 1.

Give a standard weight buffer and standard buffer spring a try and see what happens.


Does the heavy buffer have a heavy spring?
radian23  [Member]
12/25/2008 9:55:40 PM
Originally Posted By radian23:
Originally Posted By SuperiorBarrels:
Originally Posted By radian23:
I know I'm not supposed to ride the carrier down but when I do the tip of the bullet gets stuck in the feed ramps. Should they be able to freely slide in if I ride the carrier? If I let the carrier close on its own and inspect the cartridges afterwards I get small scratches on the bullets. I checked magazine feedlips and didn't notice anything. Bolt carrier doesn't have any abnormal marks. Buffer looks fine.
I have uppers that feed bullets and don't feed bullets when riding the carrier. All of them function without issue while firing. I would not worry about the scratches; it is just the way the AR15/M16 rifle works.

I am still wondering what is causing issues.

Lubricated your bolt carrier rails, inside the upper receiver, and piston rings/cylinder. Please use a lubricant WITHOUT Teflon. I use Mobile 1.

Give a standard weight buffer and standard buffer spring a try and see what happens.


Do heavy buffers come with a heavy spring? I've been using CLP. Should I be using a heavier lubricant like mobil one in addition?


jhendri223  [Member]
12/26/2008 2:33:25 PM
I just had the same exact problem with the build I just completed. I lubed the BCG and replaced the buffer and buffer spring and now it runs flawlessly.

Jim
SuperiorBarrels  [Industry Partner]
12/27/2008 1:56:50 PM
In most rifles, those heavy buffer springs and heavy buffers are not needed.
24Cans  [Team Member]
12/27/2008 4:45:05 PM
Originally Posted By SuperiorBarrels:
In most rifles, those heavy buffer springs and heavy buffers are not needed.


+1

Heavy carrier, buffer and spring, shooting under-powered ammo.


ETA: Don't forget to add a lot of lube and check for drag marks on your carrier.
radian23  [Member]
12/29/2008 11:32:11 AM
I went out and shot some heavier ammo and it ran like a champ. I'll swap out the spring next time I shoot. I'm pretty sure the heavy buffer and heavy spring was the problem. Thank you all for your help.