Never Feeds Correctly

[Nathan Gruetzmacher]

Hey all, I am experiencing a very frustrating issue with a newly finished AR-10 .308. I cannot even get the first round to feed in correctly. It always seems to get jammed into the start of the barrel, missing the chamber every time. Photos are attached. Has anyone had this happen?

I have already tried a couple of different magazines. While sighting it in I just placed each round in there by hand. I'd like to not have to do that anymore

 

[supercorndogs]

Have tried removing some rounds from the mag to make them easier to strip off?

 

[Oryx]

Check barrel extension ramp to receiver fit.
Make sure no burs on extension.


Is this a first round only issue or also a random issue if you get it running? How often is it occurring?
What magazine and style are you using?
May need some feed lip adjustments.might not be presenting the round high enough.
Pay attention to the staggered round position within the magazine ... does it only happen when the top round is on a particular side?

 

[Earnhardt]

What is the COAL of the round?

 

[tylerradke]

Hard to tell with the round in the way but something doesn't look right with feed ramps. Can you take a good clear picture of feed ramps without anything in the way

 

[msgriff]

It would help if you listed some build details, such as the mfg/model/spec of the upper, lower, LPK, barrel, BCG, mags and ammo.

 

[rpoL98]

really would like to know the brand of the barrel, seems like the feed cone is inadequate? or the feed ramps on the barrel extension are off. looks like you're using PMAGS and M80 ball ammo? those should work, if that's what it is.

long shot: is it an 80% lower? might be the mag height in the lower is off (machining of the mag release slot)? only reason I ask is some 80% lowers are sketchy in their prefab machining, like mag release cut-out, location of safety-selector detent, etc. heard from a friend-of-a-friend-of-a-friend on the interwebs.

 

[Tiribulus]

seems like the feed cone is inadequate?

Looks flat and like the nose of the bullet is sticking straight into it.

 

[bfoosh006]

Your pics look like the BCG is kinda dry, I could be wrong.
What ammo ? I remember some older 308 Norma FMJ had some seriously short ogives on their FMJ bullet, and that made them a PITA to feed in my friends SIG.

 

[Evintos]

Your pics look like the BCG is kinda dry, I could be wrong.
What ammo ? I remember some older 308 Norma FMJ had some seriously short ogives on their FMJ bullet, and that made them a PITA to feed in my friends SIG.

The entire rifle looks dry and dusty.

 

[Precision Underground]

Hard to tell with the round in the way but something doesn't look right with feed ramps. Can you take a good clear picture of feed ramps without anything in the way

This is what I was thinking. It almost looks like the barrel isn’t seated all the way. Take a pic with the bolt open and no ammo there. I can’t imagine the rifle would fire if the barrel wasn’t seated but it looks like it’s not seated.

 

[tylerradke]

This is what I was thinking. It almost looks like the barrel isn’t seated all the way. Take a pic with the bolt open and no ammo there. I can’t imagine the rifle would fire if the barrel wasn’t seated but it looks like it’s not seated.

View attachment 8006006

It almost looks like an A2 style feed ramp on the upper but I don't really think that's the case. I do think there is a piece of bullet jacket that is shaved off at the base of the feed ramps. Something is obviously catching the bullets on the way in. Also looks like the mag might be riding a bit high if anything. Really need some pics without rounds in the way. Something isn't making sense with these pics.

 

[tylerradke]

Hey all, I am experiencing a very frustrating issue with a newly finished AR-10 .308. I cannot even get the first round to feed in correctly. It always seems to get jammed into the start of the barrel, missing the chamber every time. Photos are attached. Has anyone had this happen?

I have already tried a couple of different magazines. While sighting it in I just placed each round in there by hand. I'd like to not have to do that anymore

Looks like an aero lower. Is the upper an aero as well? I see you are from California, is this modified to not be detachable magazine? On the rounds you try to chamber are the bullets gouged up pretty bad?

 

[rpoL98]

it does look like the mag is sitting too high. if the mag was sitting a little bit lower, the bullet would tip up more as it encountered the ramp, getting a better launch angle into the chamber. with the mag too high, the launch angle is too flat, bullet tip impacting flat face of barrel.

IMHO, I think the barrel is seated sufficiently into the receiver bore, just judging from how close the barrel nut is to the upper receiver face.

but agreed, the receiver bore sure does look dry.

 

[Precision Underground]

It almost looks like an A2 style feed ramp on the upper but I don't really think that's the case. I do think there is a piece of bullet jacket that is shaved off at the base of the feed ramps. Something is obviously catching the bullets on the way in. Also looks like the mag might be riding a bit high if anything. Really need some pics without rounds in the way. Something isn't making sense with these pics.

Yea the bullet is nose diving into the face of the chamber and getting stuck. The question is why. I’ve never seen an AR platform where the extension isn’t flush inside the receiver. There looks to be a gap there. There’s definitely some shaved bullet on that bottom left side where it has been rubbing.

Edit, I think what I’m seeing is the front edge of the mag. I was thinking it was part of the receiver.

 

[tylerradke]

Yea the bullet is nose diving into the face of the chamber and getting stuck. The question is why. I’ve never seen an AR platform where the extension isn’t flush inside the receiver. There looks to be a gap there. There’s definitely some shaved bullet on that bottom left side where it has been rubbing.

Edit, I think what I’m seeing is the front edge of the mag. I was thinking it was part of the receiver.

Mag s definitely up high blocking feed ramps on upper reciever. I don't have any experience with them but could it be armalite pattern mag in a dpms style lower? Is that even possible? Maybe that's why it's sitting higher in the receiver and not letting the bullet tip up high enough to enter the chamber?

 

[Tiribulus]

This is what I was thinking. It almost looks like the barrel isn’t seated all the way. Take a pic with the bolt open and no ammo there. I can’t imagine the rifle would fire if the barrel wasn’t seated but it looks like it’s not seated.

View attachment 8006006

Everything about this looks wrong to me. The feed ramps aren't really ramps and have that weird angular cut/gap space there. Seems like there's too much space between what should be the feed ramps to the feed cone and then the face of the cone looks like it isn't really concave, but is a flat ringed wall.

There's no smooth path from the mag to the chamber. In short.
I know pics can be deceiving, but this just looks... off.

 

[Jigstick]

Must be an SR25