AR Mag feed issues.

[Fastmover]

So I'm prepping my rifle for it's maiden trip (in my hands anyway).
I load up a 30 round magazine and cycle the bolt.
Low any behold, the first round jams.
Looks like the tip of the bullet was catching on the feedramps and the bolt is crushing it.
I pull the bolt back, try and slide the round back on the mag and pull the mag out.
Inspecting the round, the bolt was catching it right behind the crimp and the bullet was unseated.

I figure it could be ****ty feedramps, so I break it up and take a look.
The feedramps are ok with not signs of where a round could get caught up on.

Then I remember that I used to have issues with M16 type magazines when I was in the British Army. 30 round capacity =/= 30 rounds thus I used to only load 27 rounds in a 30 round mag.

If this still the case with steel USGI mags or are the ones that came with my rifle just odd?
Maybe it's more than just the mag and I should be looking at something else?
Or am I just crazy?

Any ideas?

 

[223 Gunner]

I'll play mister "O" for a second. Did you try another mag? Did you "ride" the bolt as it closed? I've not had many mag issues with G.I. mags, I have had a few, it usually is just a bad mag. If that is the case, you can buy a new spring and follower cheap, and check the "lips" of the mag against another too make sure they aren't bent. I have always put 30 rounds in a 30 round mag. I have had other people tell me they only load 28.
If it is supposed to hold 30, then it should hold 30.

 

[Fastmover]

Ride the bolt? Not sure what you mean there.
I pulled the charging handle and let it fly on the first round and that's when it caught.
I also tried pulling the charging handle and letting the bolt ease forward to see what was going on.
The outcome was the same. The tip of the bullet would look like it was caught on the ramp with the bolt riding over the top of the cartridge.

The magazine lips look fine to me. Not bent or anything.

 

[esrice]

What kind of feed ramp / barrel extension combo do you have?

 

[Fastmover]

Rifle extension and receiver, although now there's a gouges right underneath the ramps.
I'm going to try and put some pics up in a few.

 

[shooter521]

Then I remember that I used to have issues with M16 type magazines when I was in the British Army. 30 round capacity =/= 30 rounds thus I used to only load 27 rounds in a 30 round mag.

If this still the case with steel USGI mags or are the ones that came with my rifle just odd?

1) Downloading AR mags (we typically load 28 here in the States) is done primarily to facilitate seating of the mag on a closed bolt, but some notable instructors have reported "bolt over base" malfunctions such as you describe when attempting to load from a USGI mag that's been filled to capacity (or over capacity).

2) USGI AR-15/M-16 mags are aluminum, not steel. If you have a steel mag, it's either aftermarket or foreign, and might be part of the problem.

Try hand-cycling with your mag downloaded to 28. Try other mags of known quality (USGI with green or Magpul followers, Brownells enhanced USGI, Magpul PMAGs, etc). Let us know what you find.

 

[Fastmover]

Cycling a downloaded mag works. Hence why I thought it may have been an issue with the magazine and/or mag spring.
As for the magazine being steel, I'm probably mistaken regarding the material. It is however a USGI magazine with the green follower.

 

[Litlratt]

Also ensure that the slot in the magazine for the catch is not too high relative to the feed lips. If so, the magazine will sit too low.

 

[shooter521]

FYI, that looks like an M4 extension/receiver; notice how the bottom of the ramp cuts break the plane of the barrel extension? Unless the angle of the photo is deceiving.