What is causing this failure to feed issue?

[tasty_chicken]

Today when I went to the range to shoot my grendel, I experienced the failure pictured below. This happened at the very beginning when I had a fresh loaded magazine and with the bolt locked back, I pressed the bolt release and this happened. The round doesn't make it into the chamber. The forward assist doesn't do anything. The only way to fix it is to take the magazine out, pull the charging handle back and let go and the round will chamber. When i try to pull the charging handle it is also very difficult to pull back. I have to use alot of force to be able to get it to budge.

This continue to happen during the rest of the range session. When I got home I broke down the rifle and cleaned and lubed the entire thing. Then I tried to feed a round again but the same issue happened. What's strange is just last week I was able to get the rifle to feed and fire perfectly. Now this week it doesn't seem to want to function correctly.

Here is my setup again:
20" Black Hole Weaponry Barrel. Rifle Length Gas System
BHW Type 1 Bolt
Ares Armor NiB Carrier
Troy .750 gas block
Rainier Upper
Carbine Extension Tube & Spring, Spikes T2 Buffer
ASC 15 round magazine.

[wfa17332]

I think I just recreated the problem using a fired 5.56 case in the Grendel chamber - at least it appears to me to be the same as your picture.

If that isn't the problem, the next suspects would be some out of spec ammo or the wrong bolt head installed in the carrier.

Walt

[tasty_chicken]

I think I just recreated the problem using a fired 5.56 case in the Grendel chamber - at least it appears to me to be the same as your picture.

If that isn't the problem, the next suspects would be some out of spec ammo or the wrong bolt head installed in the carrier.

Walt

It definitely wasn't 556/223 ammo in the chamber. I was using factory Hornady 123gr amax ammo. Once I clear the malfunction and feed the round it fires perfectly and accurately. I also single feed ammo as well and that fired fine. It was when I loaded from the magazine when I started seeing problems.

[wfa17332]

I misunderstood what "continued to happen" meant. Sorry.

[montana]

Did you inspect your bolt, bolt carrier, extractor , gas tube alignment, mag catch, recoil spring retaining pin, trigger, etc ? If it was functioning OK and this happened out of the blue something has loosened up or broke. I had a disconnect break and gummed up the works one time. If you cycle the rifle empty with out a mag does the bolt carrier move freely?

[VASCAR2]

I'd look at the ejector and make sure it moves freely. If the ejector is not radiused I'd remove the ejector and put a radius on the edge so cases can easily slip into the bolt under the extractor. Look at the brass, if the brass is gouged you probably need to polish the extractor and check the spring tension.

[tasty_chicken]

I'd look at the ejector and make sure it moves freely. If the ejector is not radiused I'd remove the ejector and put a radius on the edge so cases can easily slip into the bolt under the extractor. Look at the brass, if the brass is gouged you probably need to polish the extractor and check the spring tension.

Thank you for the advice. I will check both of those items when I get home from work today.

[LRRPF52]

Things that can cause this:

Extractor spring too stiff, or has an O ring around the extractor (band aid for CLGS guns with too much dwell or large ports)
Ejector channel clogged with debris/burrs from manufacturing process
Tight BCG with too large of OD on the guide rails
Tight upper with too small ID on the tunnel (rare)
Tight chamber
Magazine location too high to the BCG, causing binding


Does it do this with different mags, or just that one? First time out with this rifle?

[ah1whiskey]

seems like i saw a 5.56 ar-15 doing this --- it had a bent gas tube and would bind on the gas key.

[tasty_chicken]

UPDATE: So I loaded up some dummy rounds (brass, bullet, no primer and no power) so I can manually cycle the action. I noticed that it would feed every other round. So if I have 1 round in the magazine, it will chamber fine. If I have 2 rounds in the magazine, it will jam up. If I have 3 rounds in the magazine, it will chamber fine and so on and so forth. So it looks like it's having issues with feeding when the round is feeding from the right side or ejection port size of the magazine.

This is not the first time out with the rifle, I've taken it to the range 3 times now. First time i had short stroking issues and I fixed that with gas block. Second time i used the same 15rd magazine with cheap wolf ammo and it cycled every round perfectly fine. The third time I experienced what I said in the OP. Between the 2nd and 3rd times the only thing I changed was I installed a new trigger. Everything else is the same.

So I polished up extractor and tried to manually cycle and it didn't help. The ejector has plenty of movement but I have not radius it yet. The magazine could be another culprit. I ordered a 10rd ASC magazine to see if it is something wrong with the mag.

[Butterbean]

Sounding like a mag feed lip needs tweaked.

[Rootshot]

Another thing to check is the "false lug" on the extractor. I've had one that was oversize and while going over the rim of the cartridge, it scraped against the barrel extension. I ground down the false lug a bit and everything was fine. The manufacturer replaced the part.

--Rootshot

[LRRPF52]

UPDATE: So I loaded up some dummy rounds (brass, bullet, no primer and no power) so I can manually cycle the action. I noticed that it would feed every other round. So if I have 1 round in the magazine, it will chamber fine. If I have 2 rounds in the magazine, it will jam up. If I have 3 rounds in the magazine, it will chamber fine and so on and so forth. So it looks like it's having issues with feeding when the round is feeding from the right side or ejection port size of the magazine.

This is not the first time out with the rifle, I've taken it to the range 3 times now. First time i had short stroking issues and I fixed that with gas block. Second time i used the same 15rd magazine with cheap wolf ammo and it cycled every round perfectly fine. The third time I experienced what I said in the OP. Between the 2nd and 3rd times the only thing I changed was I installed a new trigger. Everything else is the same.

So I polished up extractor and tried to manually cycle and it didn't help. The ejector has plenty of movement but I have not radius it yet. The magazine could be another culprit. I ordered a 10rd ASC magazine to see if it is something wrong with the mag.

There's your answer. It's either the ejector or the right feed lip of the mag.

Take a side view picture of your mag with a white background as well and post it if you can.
Radius the ejector either way. I do all of mine.

[tasty_chicken]

Okay I will take a pic of the magazine and post it up. I will also take a picture of the bolt as well.

Question for radius-ing the ejector, how do you go about doing it. Do you disassemble the ejector from the bolt or do it while it's on the bolt. What tool do you use to radius it as well.

[LRRPF52]

You can chamfer the ejector either way, but I prefer to remove it with a bolt disassembly tool, chuck up the ejector in a drill, and spin it that way. I then re-phosphate it.

https://www.youtube.com/watch?v=qlGVwb7yIUA

[tasty_chicken]

UPDATE: So I got the new 10 round ASC magazines in the mail today and it exhibits the same behavior as the 15 rounder. Jams on every other round. Here are the pictures of the bolt and the magazines. I'm going to take the bolt apart next and radius the ejector to see if that will help.

You can see where the extractor has been polished.




Here is the original 15 round magazine:

10 Round on the left, 15 round on the right.

[tasty_chicken]

FINAL UPDATE: So I think I got it working now manually cycling it. I radius-ed the ejector last night, loaded up some more dummy rounds (bullet and brass, no primer or powder and manually cycled 2 rounds, then 3 rounds, then 4 rounds and then 5, the rifle fed every round with no issues. This worked with both the 10 round and 15 round magazines. I will be taking it out to the range again next weekend and hopefully now it will run 100%.

I appreciate everyone's help and suggestions. Thanks to LRRPF52 for the instruction on radiusing. I did what you suggested with the drill. Thanks!