My M14's problem...1st stage of troubleshooting is over...more hints?

[Ripstop]

Just a suggestion.

Put some empty brass into the magazine and insert it into the receiver. Draw your bolt back and slowly let it forward just to see how much of the cartridge rim is being caught by the bolt to strip it out of the magazine. One of my magazines didn't allow the rounds to stick up enough into the receiver to be stripped out. They usually got pushed back down into the magazine. I played with the feed lips until it fed properly.

I suggest this just to eliminate problems with the magazines.

 

[Gimli]

hmmm ok

when you say gas system aligned, do you mean the gas plug?

No, I mean the gas cylinder is aligned by rifling in the barrel threads it slips through and held in place by the gas cylinder lock which actually screws around these threads. If the rifling in the barrel threads is too lose or if the gas cylinder lock isn't on tight (may require gas tube shims to be tight enough) your gas cylinder can be mis-aligned with the gas port and prevent enough pressure to go through to fully cycle the action.

If you have a chance get a copy of Hungry's M-14 clinic video, you'll understand what I'm saying a lot more easily.

 

[BBq_Woa!]

No, I mean the gas cylinder is aligned by rifling in the barrel threads it slips through and held in place by the gas cylinder lock which actually screws around these threads. If the rifling in the barrel threads is too lose or if the gas cylinder lock isn't on tight (may require gas tube shims to be tight enough) your gas cylinder can be mis-aligned with the gas port and prevent enough pressure to go through to fully cycle the action.

If you have a chance get a copy of Hungry's M-14 clinic video, you'll understand what I'm saying a lot more easily.

oh no i understand now
thanks for the clarification

 

[Grizzlypeg]

Is it possible to pull the bolt back far enough to extract and eject, but not catch a fresh round? Maybe try this with some brass only.

 

[45ACPKING]

so.... if i'm reading all this correctly......
1) your rifle loads the first round and goes bang
2) your bolt/oprod cycles back as it should to #### hammer
3) on it's way back to battery your bolt picks up the next round and fails to feed.

i am gonna bet this IS a problem with the oprod spring either being weak or being impeded by the recoil buffer. I'm thinking as long as your gas system is clean and dry it is not the problem. you stated already the piston had a slow free fall from the cylinder... this is good and indicates proper port alignment. A slightly loose , for and aft, gas assembly won't cause what you are experiencing.
before us armchair gunsmiths hehehe myself included..... cna further diagnose this..... remove the buffer, leave everything else as is and shoot the rifle........ give us a report when you get back from the range.

 

[BBq_Woa!]

so.... if i'm reading all this correctly......
1) your rifle loads the first round and goes bang
2) your bolt/oprod cycles back as it should to #### hammer
3) on it's way back to battery your bolt picks up the next round and fails to feed.

i am gonna bet this IS a problem with the oprod spring either being weak or being impeded by the recoil buffer. I'm thinking as long as your gas system is clean and dry it is not the problem. you stated already the piston had a slow free fall from the cylinder... this is good and indicates proper port alignment. A slightly loose , for and aft, gas assembly won't cause what you are experiencing.
before us armchair gunsmiths hehehe myself included..... cna further diagnose this..... remove the buffer, leave everything else as is and shoot the rifle........ give us a report when you get back from the range.

it doesn't pick up a new round.
it cocks, but closes on an empty chamber (i.e. doesn't strip a new round)
and yes. for now the buffer is what i'll try (and the checks i performed before)
everything else seems fine.

alignment seems fine too, to adress the earlier question

 

[45ACPKING]

closes on an empty chamber?? i missed that entirely
nothing in the gas assembly or oprod system would cause that ..... i don't think

maybe it's a mag/bolt interface issue....... when you take it to the range, load 2 rounds. this will place the first shot on the right hand side of the mag. chamber the round...... any hitches? did it pick up the next round from the left hand side of the mag? Then try it with 4 rounds for added mag spring pressure..... make note of glitches. If it has issues with picking up that first round from the right hand side..... it just has to be a mag lip or follower issue
maybe your mags have a right hand side feed lip deformation?
I dunno??? without a hands on..... at this point i'm stumped....

I have had several norc 5/20 round mags and one 5/5 round mag that would cause the right hand side round to nose dive into the front edge of the magbody when rounds were stripped by hand. I have come acustomed to inspecting all the followers now. What i have found was in all these cases, probably 5 mags now.... the rear tab of the follower is bent in too much and is not 90 degrees to the top of the follower. This allows the follower to tip forward enough to nose dive the round.... but only the round stripped from the right side....... man... some pics of what i mean would come in handy....
strip a mag and see if that rear tab is bent in a bit

 

[BBq_Woa!]

I doubt it's the mag
I've used a 5, 10, and 20 rounder with it and have always had similar things goin on.


also, keep in mind, when it does do the failing to feed thing, it does it every shot. not just from a certain side of the mag.

 

[45ACPKING]

can you measure your bolt with a caliper , thickness from top to bottom at the front and thickness of the left lug

 

[Ripstop]

I doubt it's the mag
I've used a 5, 10, and 20 rounder with it and have always had similar things goin on.


also, keep in mind, when it does do the failing to feed thing, it does it every shot. not just from a certain side of the mag.

Have you tried my suggestion?

I don't think that it is the magazines. I think it may be a problem with the magazine to receiver interface. OR as 45ACPKING is now suggesting, a magazine to bolt interface. When you manually pull the op. rod back and let fly, the force is less than when the rifle does this automatically. Doing this automatically, there may not be enough of the rim catching and it may push the cartridge back down in the magazine allowing the bolt to ride right over it.

You may also want to compare the contours of your op. rod spring guide to another since this is the front latch that locks your magazine into the receiver. It is a cheap stamping and may be deformed.