What have I done?

[bushmeister]

Thanks MB thats the one I followed. Well I just got back, and unfortunately got the same result . so we know it's not lube or gas rings. I ran the test, and it does not catch in the open position on the last round. It does, however if I manually pull it back.

[halfslow]

Sounds like someone else said: you have a gas problem.
Check the setscrews under the gas block for tightness.
If loose, it is possible that the gas block has moved from the gas port.
I don't know if it is possible to loosen the set screws and see how the gas block and port line up.
I don't plan on trying this on mine at this time.
Of course, be sure and check that there is a pin in the gas block holding that tube in the first place.
It is also possible that the cleaning (which we all must do anyway) pushed some debris into the gas port and partially blocked it.

[MudBug]

Thanks MB thats the one I followed. Well I just got back, and unfortunately got the same result . so we know it's not lube or gas rings. I ran the test, and it does not catch in the open position on the last round. It does, however if I manually pull it back.

That right there tells us that you are definitely not getting the gas pressure you need. So something in the gas system is out of wack.

What we know so far;

1.) It did work the first time you took it out. So something has changed.

2.) You checked the gas key and it's installed properly.

3.) You used the pipe cleaner on the gas tube (don't feel bad, they actually sell them for that purpose. I actually have some I bought years ago with my first AR, I just got lucky and was warned off before using them)

I'm gonna have to guess here that something got pushed in to block the gas some how (Though I'm kind of surprised that is has been forced out by now.

halfslow also has a good point, it could be that somehow you gas block has come loose or moved a bit.

If it was me this is what I would do.

1.) Remove the whole gas system. Gas Block, and Gas tube from the rifle.

This shouldn't be that difficult, it's just a matter of removing the screws in the bottom of the gas block (First put an alighnment mark on the block and barrel so you can put it back in the same place) then pull off the gas block, this will take the gas tube with it.

Then knock out the gas tube roll pin

Then pull out the gas tube.

Inspect and clean everything, make sure there is no blockage, then re-assemble. Use some red or green loktite on the screws to hold them in place (Red will hold better with all the heat, but will require a torch or heatgun to remove the screws later if you need to)

Go shoot it.

[halfslow]

Have you checked that the BCG slides into and out of battery with only a little drag?
Pulling the carrier back with the charging handle will not show up interference between the charging handle and the gas key.
With the upper open, that is, not pinned on the lower, you should be able to push the carrier back to it's full open position and back into full lock with your finger through the ejection port. You will feel any drag that exists. There is not much.
If the charging handle is squeezed in or bent, it could slow the BCG enough to prevent full stroke.

[gunnut]

Reading all the post leaves only 2 places to look on the gas sys. (1) the gas block may have moved. I've had it happen on other AR's. same results. (2) 30,00 PSI, Anything in the gas tube will end up in the bolt key. clean THIS with a pipe cleaner.
Other than that I would look at the buffer assembly. Anything in there other then the correct and properly installed buffer and spring?

[2zero6]

With the action open or the upper off spray a whole bunch of clp in the gas tube above the chamber with the straw, leaving the muzzle pointed down to drain. If nothing drains it is plugged. make sure you blow all the clp out if it isnt with an air hose or airduster can with a straw.

[wildcatter]

OK, here is my gas key. It does not move whatsoever when I try to wiggle it. Can you tell if the stakeing is correct? Do I need to break out the allen wrench on it and see if I can tighten it? (edit: I went ahead and checked it with an allen wrench and it is tight.)
[ http://farm3.static.flickr.com/2459/3953060405_e35ec91c98.jpg ]
MB, do you think there could have been enough gunk in there after just 60 rounds to actually block the tube? The cleaner came out with just a little slightly dirty oil on it. No real gunk to speak of.

The carrier looks like it's staked OK, not as heavy as I like, but fine, and as long as it's not loose then that is not the problem.


As far as the gas tube goes I just don't know for sure if that is the problem, I just know that you shouldn't do the pipe cleaner thing, it can lead to the symptoms you are having. As Siringo stated, it sounds like you are under-gassed.

Try this.

Load one round in the magazine, chamber, and fire. (Of course leave the magazine in place)

Does the bolt go back far enough for the Bolt Hold Open latch to work? Does it lock back on the empty magazine?

If not then you are not getting enough gas pressure to push the BC/Bolt back far enough to pick up the next round.

If it does then we are probably looking at some kind of magazine problem.

Big huge 10-4. You need to isolate the problem, which can easily be over come and is actually small as far as things go. Do The Bugger's suggestion first, looking for the mag to hold open, then if it doesn't, like MB says it is most likely a mag problem...except, for your messing around with the tube, this could still be an under-gassed situation, and you'll then need to revisit the entire system, really doing a clean job and no lube to the parts that carry the gas directly, but don't fret, we are all over it and are happy to be of assistance, your turn to help will come... and BTW Bushmeister, a hardy Welcome Aboard 'ol man..

[bushmeister]

[/quote]
Big huge 10-4. You need to isolate the problem, which can easily be over come and is actually small as far as things go. Do The Bugger's suggestion first, looking for the mag to hold open, then if it doesn't, like MB says it is most likely a mag problem...except, for your messing around with the tube, this could still be an under-gassed situation, and you'll then need to revisit the entire system, really doing a clean job and no lube to the parts that carry the gas directly, but don't fret, we are all over it and are happy to be of assistance, your turn to help will come... and BTW Bushmeister, a hardy Welcome Aboard 'ol man..[/quote]

Thanks for the welcome. I'm really enjoying learning about these guns. I'm travelling this week for work, but I brought the BM with me with the hopes of rectifying the situation. Plus, theres always a shooting range somewhere, and Deer season is closing in fast. I appreciate everyones willingness to help on this.

Other than that I would look at the buffer assembly. Anything in there other then the correct and properly installed buffer and spring?

Hmmm. funny thing you should ask about that GN, I did add a limbsaver pad on it, and wondered it that vent screw on the buttpad being blocked might keep air from escaping in that buffer tube. particularly after adding a little oil to the walls?

[wildcatter]

[/quote]
Hmmm. funny thing you should ask about that GN, I did add a limbsaver pad on it, and wondered it that vent screw on the buttpad being blocked might keep air from escaping in that buffer tube. particularly after adding a little oil to the walls?[/quote]

Double Hmmm... but isolate the problem first and I usually recommend that you do one thing at a time, so as to know and understand just what you did to fix the problem.. What we are trying to do is to understand the science and if you do everything that has been recommended here, all of which is correct, then if the problem goes away, well, you'll never understand what the problem was and we here will be left scratching our heads too..Go slow with this one, it'll make you and us, by proxy, a much better gun crank..Keep using the Bugger's one shot method with an empty mag installed, again, you're looking for the bolt to hold open..

[bushmeister]

Went to the range today, with my factory buttstock back in place, I got the same results. before I went, I did go through the inspection of the buffer spring area, with nothing to report, other than that I spotted the air relief areas that pretty much squashed my buttpad idea. I also checked the gas key again with a qtip, and blew in it without any noticeable restriction. as you suggested, everything seems to point towards the gas tube, or an alignment issue. I guess it's to the point that a procedure other than that recommended by the manual is required. I'd love to get this thing fixed, and I'm mechanically inclined, but I don't want to void the warranty by getting into the gas system.....thoughts?