AR Failure to Feed - Please Read

[TetsuFury508]

I've done a lot of reading and I believe I have pinpointed the issue through trial, error, and testing. Just need a second set of eyes on this so bear with me.

Since building my midlength 5.56 AR I have had issues with dropping the bolt on the first round of a magazine. After I fire the first round, I believe there is enough energy to return the bolt and give enough force to feed the next round. I do not believe this is short stroking or just running dirty. Changed mags, didnt fix it. Lubed it. No go. Tried cleaning out the mags and scrubbing the gun. Nothing. Different ammunitions, still, not feeding. Turned to the forums and did a lot of reading and window shopping to see if I could figure this out.

That being said - I am 99% sure I need to look into a heavier buffer tube spring. I am leaning toward this the most, as it is the least expensive option, and because my issue seems to only occur when I initially drop the bolt on that first round.

Also looked into a heavier buffer tube weight, but I have read that the heavier the weight adds more recoil. More interesting than anything right now - I have been seeing some guys completely strip the buffer tube guts and run a heavier gas block to provide more backflow.

Any ideas?

[ianb1116]

What does the failure look like? Is the bolt just skipping over the round? Buffer springs are not where you should be looking IMO. If it's overgassed, a heavier buffer may be the answer, or an adjustable gas block.

[TetsuFury508]

Good point....

The failure appears to be taking the round only half way out of the mag. So it is starting up the ramp, not jamming, but just failing to completely come out of the mage and into the follower. Thats why I was thinking a heavier spring could maybe knock it forward with more force.

I haven't touched the gas block FYI - just read about guys messing with that versus springs/weights/etc.

[daddy]

Do you overload your mags? 30 rnd pmags will take 31 rnds and not strip the first rnd because it is jammed against the spring.

[JDA58]

If you can try it with a different bolt...
One of my ARs would do something like this when new... switched bolts and it was fine.. just did it with that bolt.. maybe not as mil spec as it should have been... too much coating/finish ??... runs fine now after using it awhile

[stack$99]

Is this a factory built upper? I would examine your gas block to make sure everything is lined up square, also check gas tube. Changing buffer would obviously be the easier place to start.

[danhr]

Sounds like a buffer and/or buffer spring problem.

Load one round into a magazine and fire. Does the bolt lock back? If so, then you know that the bcg is moving back far enough, it just doesn't have enough energy on the trip home. If it doesn't lock back, then you probably have gas issues.

If you have gas issues, the first question would be what kind of gas block is on it

If it's locking back, I would probably say it's the buffer spring. It could be the buffer if you are running a heavy buffer.... so if this is the diagnosis, you could try running a heavier a buffer, but that's a long shot in my opiniin. I generally just run a carbine buffer in everything with an adjustable gas block and don't have any issues..... From short pistol gas systems on a 10" barrel, up to a rifle length gas system on an 18" barrel


You said it's a mid length system, but what's the barrel length?

[TetsuFury508]

Factory built upper from Palmetto state. I believe its a 20" barrel. Nickel boron BCG.

[TetsuFury508]

Shot in a 3gun Comp today at Sandy Creek Conservatory and had it hang up twice! haha so trying to get this fixed before next months shoot!

[arjohnson]

Since it's a 20" upper try an A2 stock assembly with rifle buffer and spring. Can't recall ever seeing a mid-length 20" upper, are you sure it's 20 and not 18?