450Bushmaster.net

Hi everyone, I'm new to AR's, but picked up my carbine a few weeks ago. Out of the box, I shot 3 boxes of factory ammo out of it without a single problem. I took it home and cleaned it, and i took it back out, and it started to not load every 3rd shot or so...(by not load, I mean it ejected the previous round, but the bolt did not pick up a new round on it's way back to the chamber.) when I would try the next shot, just "click". When I pull back the bolt manually, a round would feed into the chamber properly. So, I took it back home and cleaned it again....Now it does this everytime. I've taken it back apart and cleaned it again, consulting the manual this time. Before I take it back out, I thought I would consult you guys to see if there is anything else I should look for, or do.

1. I've read the posts about new rifle syndrome, but since it shot fine before I cleaned it, I'm suspicious that this might be self inflicted.
2. I used rem oil as a lube for the moving parts (I saw the video with wheel bearing grease, but really?)
3. on the last cleaning, I found that the rings on the bolt were staggered 20-30 degrees apart instead of 120. It didn't look like any gas would escape, but I have re-staggered them now
4. Since it feeds fine when I manually pull the bolt back, can I dismiss the magazine as being the culprit?

Thanks,

Mark

Something changed! Are you still using factory ammo? What type of mag are you using? Is this a stock factory gun from Bushmaster?

In order to help us help you -- please detail you cleaning procedures, what you cleaned, how you did it, solvents used, lubes used, ect.

The ring spacing is not all that critical -- I have shot my deliberately with all the spaces lined up and it works fine. Just stagger them and everything should be AOK.

Sounds like something is wacko with the gas system. Did you attempt to clean that?

Factory 16" carbine, Factory mag, Factory Hornady 250gr ammo.

Cleaning procedure
1st time Barrel: patch of Hoppes #9 copper solvent, 1 min, then chase with a clean patch. Then boresnake, then boresnake with a little rem oil on the tail of the snake. Action: it didn't look all that dirty so just removed bolt and t-handle wiped with a clean patch, quick spray of rem oil, and reassembled. Spring loaded tube in stock: quick spray of rem oil, pushed it in a few times with my finger to lube the walls.

2nd time: barrel:same as above, but also brushed out the chamber before snakeing with a brass brush. action: same as above but this time I disassembled the bolt, firing pin, lugs, etc and cleaned well with pipe cleaner, then oiled moving parts, reassembled. also ran a pipe cleaner into gas tube above barrel.

First, Rem Oil sucks for ARs, it doesn't hold up well in a semi-auto and all the heat in a DI system. I doubt that is the problem here, but just so you know. And Yes, Moly bearing grease works great unless you live in some kind of frozen place. I used to use regular moly bearing grease but know I use Super Lube. I also use Slip 2000.

Now, for your problem.

Check the gas key, it may no be staked correctly and is slowly coming loose.

This is the gas key..



And this is what a good staking job should look like.

bushmeister wrote:Factory 16" carbine, Factory mag, Factory Hornady 250gr ammo.

Cleaning procedure
1st time Barrel: patch of Hoppes #9 copper solvent, 1 min, then chase with a clean patch. Then boresnake, then boresnake with a little rem oil on the tail of the snake. Action: it didn't look all that dirty so just removed bolt and t-handle wiped with a clean patch, quick spray of rem oil, and reassembled. Spring loaded tube in stock: quick spray of rem oil, pushed it in a few times with my finger to lube the walls.

2nd time: barrel:same as above, but also brushed out the chamber before snakeing with a brass brush. action: same as above but this time I disassembled the bolt, firing pin, lugs, etc and cleaned well with pipe cleaner, then oiled moving parts, reassembled. also ran a pipe cleaner into gas tube above barrel.

THIS MAY BE THE PROBLEM.

Do not do this, not ever, "Just say NO!"

the gas tube is self cleaning. Think about it, that gas go through there at very high pressure, do you really think it's possible that it left something in it that you can clean out with a pipe cleaner? More likely that you loosed stuff up just enough to push it into big solid glob that's then solidified and is blocking the gas tube, so you are getting just enough movement of the bolt carrier to eject the fired round, but not enough travel to pick up the next round. (Same symptoms as a loose gas key).

If that is the case then the only way I can think of to solve it is to remove the roll pin that holds the gas tube in the gas block and then run the pipe cleaner or something else completely through it to push out the glob, and then inspect the gas block to see if there is a glob of crap stuck in there.

I am suspect of the pipe cleaner. Make sure nothing got left, shoved or stuck in the tubes. From your symptons -- it sounds like your not getting enough gas.

I do not know about others, but I have put well over a 1000 rounds thru mine and I have never cleaned the gas tube.

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.)

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.

bushmeister wrote: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.

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?

OK, I've got all the rem oil out, and moly grease in. It does cycle much smoother by hand. I'm headed out to shoot it, and will perform this test when I do, and will report back this evening. If it doesn't work, I guess I'll need to see how to remove the gas tube to inspect. Thanks for the help guys!

Keep in mind that when using grease you don't need to coat everything. Check out THIS video, Yeager does a good job of showing how to use it.