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Discussion Starter · #1 ·
My brass ejects in the 1-2oclock position an yesterday at the range for the first time my bolt didn't lock back on the last round. I've heard that these are signs of it being over gassed. Is this true? An if so my best bet would be to get an adjustable gas block right?
 

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If the bolt doesn't lock back, it could be over or under gassed. Many possible causes. If it operated properly in the past, and you are using the same ammo as before. It could be that it's dirty and not cycling far enough back to engage the bolt catch after the last rd. Have you checked the condition of the catch? are you using a mag that has worked before? The mag follower pushes the catch up so that it can engage the bolt. Sometimes a rifle that is over gassed will have bolt ride over and not engage the catch. Is his a new (to you ) rifle? You could try milder loads to see if it helps. If you have a problem with it being over gassed, A heavier buffer can slow the cycling down. But I prefer the adjustable GB so that I can tune the gas impulse.
 

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Discussion Starter · #4 ·
I've been using the same pmc x-tac 62 grain since I got it. I've inspected the bolt catch an it appears to look in good condition. This is the first time it's not locked back but it's also the first time I've used my new mags as well. I suppose it could be the magazine as to why it didn't lock back. Although that dosnt explain the spent brass that literally ejects within arms length at the 1-2oclock position
 

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Afa not locking back, I'd suspect your new mags. How many rounds through your gun? Could be a weak buffer spring
 

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I agree with ripcord.
Might want to actually clean the inside of the gas tube every now and then.
I see a lot of problems with cycling that are caused by lack of proper lubrication too.
People tend to run ARs way too dry.
 

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What weight is your buffer weight? That could be an issue...
If you believe your rifle is over gassed. Make sure you have a full auto bolt carrier (heavier than semi). Change the buffer to an H3(If H3 is too heavy you can swap weights with standard buffer to get weight you need). And try a heavier action spring. (Buffer spring).
 

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A lot of theories, but first off I would like to know your set-up before I would venture a guess. Most gas problems are encountered with "carbines", and "short" gas systems.
From your description, short ejection, and bolt failing to lock back after last round in magazine, to me signal not enough gas. Something as simple as gas ring gaps too close in alignment. Since you are using PMC X-Tac ammunition, there shouldn't be a problem with underpowered ammunition.
 

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Discussion Starter · #14 ·
It's a carbine length gas system. I have noticed though that the brass deflector has scuffs on it very close to the ejection port. An as I said it only didn't lock back 1 time an that's with new magazines I never used before. An having put about 5 to 600 rounds through it. An I've checked the gas rings after my last range day. The gaps are as thy should be.
 

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Discussion Starter · #15 ·
I figured the problem out guys. The failure to catch the bolt was due to the magazine. I found this out today due to the fact that the same mag that it didn't hold open on didn't feed one round into the chamber all the way an ended up pushing the bullet into the casing. As for the ejection pattern an how far I changed out my full auto nickel boron bcg with my phosphate semi auto an they started to eject more consistently at a 3oclock pattern. I believe it was the gas keys on the full auto bcg cause when I first got it I had to get them properly staked cause when I first got it they weren't. But it seem even when they did "properly" stake them it still wasn't up to spec
 

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Gosh.

I gotta say, as an old wood and iron
gun guy, that whole discussion is a bit
intimidating.

I was thinking about finally adding a
Colt 6721 to the stable - a carbine length,
that has the be the HBAR as I live in
Maryland. But, all the fancy
maintenance and PhD-level
physics seemingly needed for the
reliable operation of an
AR-15 platform may be a drain on
the fun factor.

I can deal with the mag issue, but rings, buffers, etc.
Huh?

Or, is it really routine in the world of black rifles?
 

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Thank you, Snyper!

I guess just about anything mechanical
is covered on YouTube these days.
A brave new world, indeed.

But, you know, I am an Old Fat Guy
who would probably be better off
having my hand held as I am walked
through a hands-on process. I also
think I need a really patient or heavily
medicated and knowledgeable
instructor who can answer my
questions - that he or she
will kindly assure me are not stupid -
even though I know they probably will
be.

As I noted, I live in Maryland, so I am
limited to an HBAR. The 6721 is still
legal here - for now - and from what
I have read is a good entry-level
rifle, despite mixed reviews on weight
and balance, and the 1:9 barrel.
Clearly, the subjects for other threads.

I guess I have to learn sometime, and
this thread convinces me an AR is not
as much a plug-and-play as the
blessed subject of this forum.
 

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My brass ejects in the 1-2oclock position an yesterday at the range for the first time my bolt didn't lock back on the last round. I've heard that these are signs of it being over gassed. Is this true? An if so my best bet would be to get an adjustable gas block right?
Ejection pattern is not a solid indicator on the AR platform as the brass usually bounces off the brass deflector. If the bolt did not lock back, it is not fully cycling and would indicate an under gassed or incorrect spring or buffer.

Could also be either under powered ammo or an anomaly if it only happened once.
 
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