Mag and feeding problems

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Re: Mag and feeding problems

Postby Hoot » Thu Feb 20, 2014 5:23 am

Sesshoku wrote:Here is the video I shot today. I have each clip in regular speed then a short replay slowed down to 10%. I sure hope this shows someone what the heck is going on. Well, besides my bad form.

http://youtu.be/bsc5XOJLucQ

At the end of the clip, I tried to show the gouge in the brass of the live round after it got jammed. It doesn't show up well partly because it was the smaller gouge of the three times it happened. The first two dented the brass a good 1/8th of an inch.


I looped on that FTE about 20 times and it looks like either a gritty or weak ejector plunger, or when Bushmaster milled the ejection port, they milled too little or left an inward facing rough edge around the rim of the opening that's catching the case occasionally. My primary feeling is the plunger though. If it were me, I'd drive out the retaining pin, remove the plunger and inspect the spring. Stick a tube from a spray can down in the hole and give it a squirt to dislodge any possible debris. Alternately, polish the plunger on a wheel (no simple task) or with a dremel and a polishing fob. The plunger spring tension should be so strong as to almost be impossible to push it all the way in with the tip of your finger. When it successfully ejects a case, how far does the case fly away from the gun? If it's a ways off, then perhaps look at the ejection port milling job. Look for brass smudge or actual buildup where the cases are possibly hitting. Lastly and I know it's expensive burning through ammo to troubleshoot, remove the magazine before each shot for the number of shots it typically takes for an FTE to occur and see if they stop. The mag may be sitting a little too high and is deflecting the cases upward as they travel back. Then when they clear the barrel extension and begin to flip out, that upward deflection makes them run into the top of the ejection port.

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Re: Mag and feeding problems

Postby Texas Sheepdawg » Thu Feb 20, 2014 5:33 am

Here is a little video that I shot regarding the ejector and extractor. I forgot all about making this one.
http://youtu.be/yLY84nk0l3g
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Re: Mag and feeding problems

Postby Jim in Houston » Thu Feb 20, 2014 5:40 am

Not much to add to what Hoot has said, except that I would suspect the damage to the brass is the result of the bolt slamming into the case or slamming the case against the ejection port, when the brass stovepipes.

I use the bottom of an empty case to push on the ejector, when I clean the bolt assembly. It should (in my experience) be quite difficult to push in, but it should go in smoothly and spring back quickly. To lubricate it, I put a drop of oil on the bolt face and push the ejector in and out several times so that the oil goes down along the ejector shaft.
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Re: Mag and feeding problems

Postby Texas Sheepdawg » Thu Feb 20, 2014 8:11 am

Okay I watched the video. And I have a question. Does the gun only malfunction when your left hand is gripping the mag well? Just how tight are you squeezing the magazine and well? I'm wondering if there may be a possibility that there may be
some kind of unusual torque being applied to that magazine that's causing the mag lips to hang up. That's just from my first observation. Now I'm going to watch it over and over and see if anything else strikes me. Now, I know that typically, an AR won't usually misfeed when held the way you're holding it but I'm just trying to point out that possibility.
Okay, back to You tube. And yeah, I subscribed to ya.
Addendum.
I'm starting to suspect that your ejector spring needs to be looked at.
Have you completely disassembled and inspected that bolt? It looks like the extractor is doing it's job.

PM sent.
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Re: Mag and feeding problems

Postby Sesshoku » Thu Feb 20, 2014 12:38 pm

Thanks again guys. I really do appreciate your help.

Hoot, when it ejects the brass is kind of all over the place. The most consistent spot is usually about 5 away at 2:00 to my position. Sometimes it's closer to 1:00 to my position. I have not pulled the ejector out yet but will try that route next. I have pulled the extractor and cleaned it a couple of times but I have not pulled the ejector. I've only checked its operation by pushing it in (with the aid of my punch). Couldn't push it all the way in with my finger.

Sheepdawg,

I just got your pm and will try to get with you yet tonight if my times coordinate with yours. If not, I am free most of the day tomorrow until I go to work at 4:30 EST. I haven't noticed this issue issue being limited to just when I hold my grip on the mag well, but I will be aware to change my grip to the hand guard and see if that changes anything on my next range trip (hopefully Sunday). I can say that when I fired my last 5 rounds of the day yesterday, I loaded only one round in the mag at a time and had no failures to eject on each shot. I did however, have failures earlier in the session also just loading one round per mag, so I can't say it happened or didn't happen consistently under either condition.
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Re: Mag and feeding problems

Postby Texas Sheepdawg » Thu Feb 20, 2014 12:54 pm

As far as the ejector goes, I do remember some people saying that they were having issues with their bolt and poor ejection and when they took the ejecter out, there were steel millings-filings tangled up in the ejector spring.
Also. Under the extractor, there is a tiny little spring with a tiny rubber buffer inserted inside that spring. I think mine was blue but it could be any color. Can you confirm that your extractor has that tiny buffer inside the spring?
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Re: Mag and feeding problems

Postby Sesshoku » Fri Feb 21, 2014 2:07 pm

Another update …

It's time to get the big guns involved. Sorry, bad pun.

I spoke with Texas Sheepdawg and showed him these photos. Shortly after seeing them, he spoke with Wildcatter. The consensus: call Bushmaster right away. Something is just not right. So, listening to their wisdom, I got on the horn with Bushmaster customer support. We went through a few troubleshooting items. They had me check the gas rings and push the ejector in. These things checked out, so I explained about the markings on the bottom of the brass, which you'll see in the photos. They said they'd never heard of that happening and were frankly at a loss. Obviously, there is a problem. They wanted me to send in the whole upper to diagnose and repair, but they were concerned that I wouldn't have it back in time for my Florida hog hunt in a few weeks. BTW, Bushmaster, if you're reading this, I appreciate that consideration.

Anyway, so they are now shipping me a new ejector rod, ejector spring and ejector rod retaining pin with the hopes that installing them will either solve my issues or get me through my hunt. If there are still problems with the new ejector, they told me to ship them the upper and they will make it right. I do hope these new parts make things work because I'll tell you, it's getting frustrating. Thanks to everyone who has helped me so far.

And, the photos. Please note, I made these photos before cleaning any parts to try to give clues to those of you who know more than I.

This photo shows the circular marks on the bottom of the brass. It appears the ejector rod hit the brass several times. I've got no clue how or why this would happen

Image

These cases took a beating.

Image

Lots of brass shavings on the face of the bolt and even had some brass shavings in the mag.

Image

Finally, here are the parts of my bolt and carrier disassembled. I could not get the ejector retaining pin out in order to remove the ejector and spring.

Image

Close up of the extractor. Sorry, I leaned forward slightly with my camera and ended up with the bolt in focus and the extractor out of focus.

Image
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Re: Mag and feeding problems

Postby Hoot » Fri Feb 21, 2014 2:27 pm

Ooh! You have an overgassed rifle, complete with all the telltale symptoms. Best advice would be to send it back to the factory along with those cases. The bad news is that means some down time right when you are wanting to shoot it the most, but that is the best approach. I bet is comes back with a new barrel that has the correct gas port size. I assume your RRA lower has the original spring and buffer it came with? The first 2k rounds through my 450b was on the same lower and it did not suffer from that with factory loads.

Call and get an RMA

Hoot

Edit: don't send back the magazine. You already put too much work into it. ;)
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Re: Mag and feeding problems

Postby Sesshoku » Fri Feb 21, 2014 3:00 pm

That was not the news I was hoping to hear.

I bought this rifle for a hog hunt and to be my deer rifle. My guess is there is very little chance (read almost no chance) that I get the upper back in time for this hunt four weeks from now even if I overnight it to BM right now.

And, no, I won't be sending any mags back. You're right. That was already enough of a p.i.t.a.

Thanks for the info, Hoot.
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Re: Mag and feeding problems

Postby lungingturtle2 » Fri Feb 21, 2014 6:48 pm

Wouldn't it be nice if Bushmaster monitored this site so we could refer them to the pics here so they could see what was happening and decide on a course of action for the owners. That would make great customer service and repairs could be expedited.
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