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Failure to eject/extract


Scott76

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1 hour ago, Albroswift said:

@Scott76

But what i'm asking is did you try  turning it down, the other way, not bleed off but closed a click at a time? What brand block? 

Superlative arms.  No, I never did try it on the restricted settings. I should probably just throw a standard block on the thing, I only bought this one because it will end up being suppressed in the future, but not anytime soon.

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Just saying, before you do anything else try shutting it down a bit. I have had builds that extracted unreliably from too much gas, closing the gas block down a little fixed it right up. Last one, mid length 6.5, running at about 2 in from full open. Before that, 308 somewhere between carbine and mid, 2-1/2 in or so. Ports at around .08something if I remember. Seen other posts that bleed off blocks don't bleed enough for 308's to make a difference.

Edited by Albroswift
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@Scott76, I meant to add this last night, just as an example of the things that companies are doing with this platform.  It's nothing directly related to your situation, but it's in reference to the lack of a spec or pattern to follow.

Rifle receiver extensions are 9 11/16" internal depth.  That's the same for .308ARs, AR15s (regardless of "A1" or "A2" stocks).  That's the standard for rifle receiver extensions. Now, to have the proper BCG total travel in those extensions, the Rifle Buffer for a .308AR should be 5.200" long.  I harp on that all the time.  Here's a .308AR rifle buffer from a very well known company, and it's too long.

986066822_308riflebufferbad.thumb.jpg.05725fcc86841f88a9fa507290f049d5.jpg

That extra 0.084" on length can make a difference in the BCG travel, and cause issues in the cycling of the gun.  Examples of that could be - BCG doesn't lock back on last round, BCG doesn't strip the next round in the magazine...  It's definitely longer, so it's gonna beat up the buffer bumper in the end of the extension more than one that's to the true dimension of 5.200" long...

Here's one that's right on the money:

2016506945_308riflebuffergood.thumb.jpg.87c0fbcd1d1e09dd7c0e41f53ec2cd38.jpg

Here's the visual difference between the length of the two of them:

1027556817_308riflebufferbadandgood.thumb.jpg.3de31f14ac33d0fa2321385b25bfba72.jpg

Now, let's say you wanted to add one of the old-school Tubb Carrier Weight Systems to your BCG, and add another 4 oz to the cyclic weight.  The Tubb CWS adds 0.080" to the length of the carrier.  Will it work on a 5.200" buffered-rifle?  You have to test and find out...  Will it work on a 5.284" buffered-rifle?  You're cutting that spec down even more now, and running a 5.364" buffer, effectively...   More issues will arise - will the BCG lock back on the last round?  The nearest I've seen on systems that are built right is 3/16" of travel of the bolt face, past the bolt catch, when you hold that BCG all the way to the rear, and measure.  That's proper travel.  3/16" = 0.188"...  

Things aren't looking good for the buffer that's longer, if you want to run the Tubb CWS...  However, in theory, if I can run a 5.200" buffer AND the additional 0.080" of the Tubb CWS still works...  then the 5.284" buffer would work, too, right?...  Yeah, it certainly should.   If I was stuck in that situation, I'd cut the buffer bumper down, not ideal, and you'd have to closely monitor the condition of that buffer bumper...

You can see in the comparison pic of the two buffers - the longer one actually has a longer buffer body - the buffer bumpers are the same...  You could shorten the buffer body by 0.080", but you'd have to re-drill the roll-pin holes 90 degrees off.

Just an example of companies doing whatever they want...  

And just think - there was a new guy here recently that was trying to argue that the "spec" of .308AR rifle buffers was 5.200" TO 5.500"...   Hmmm, really...  Run a 5.500" long buffer, and you'd never even be able to manually lock the BCG to the rear, and it certainly wouldn't do it on the last round in the mag...

 

Edited by 98Z5V
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Good points. At this point I’m in a bit of a holding pattern since the range I use is pretty much underwater.  I’ve installed the KAK extra power extractor springs and ejector spring in the bolt. They were cheap, I figured why not.  Also based on what you guys have said the gun still isn’t broken in, gonna throw at least 100 more rounds down range.  Current plan is to go back with the gas block wide open and see what happens, maybe even try the restrictions. Who knows, trying is free. 

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An update of sorts, got an email back from Faxon just outlining my setup to them and asking if there was any glaring mistakes. My gas block is spaced .016” from the shoulder, as I always take measurements to center the ports up. They are telling me to run it right against the shoulder. 

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6 hours ago, Scott76 said:

An update of sorts, got an email back from Faxon just outlining my setup to them and asking if there was any glaring mistakes. My gas block is spaced .016” from the shoulder, as I always take measurements to center the ports up. They are telling me to run it right against the shoulder. 

That won't matter, for the diameter of the gas port in the barrel, and the max diameter that gas blocks are drilled to - they're all drilled to 0.125" in the block, because that's the max diameter of the inside of a gas tube.  With that gas port diameter, you can easily account for the the shoulder-placement of a gas block, or spacing it 0.016" forward.  The hole in the gas block will still fully cover the diameter of that gas port, if you put it at the shoulder, or space it the 0.016" forward...

This is something that you really need to pay attention to on a 16" rifle gas barrel that has a 0.105" gas port diameter - gas block centering over the hole is pretty important in that case.  Not with your case, though.  There's enough overlap, because Big Hole in gas block will cover Little Hole in barrel, almost every time.

Edited by 98Z5V
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4 minutes ago, Sharpshooter said:

Geez, you sound like something I heard a lot of years ago: big girl, big hole; little girl, all hole. So far, it's sorta proved true. :hump:

That's what it all comes back to, for real... :lmao:

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6 hours ago, 98Z5V said:

That won't matter, for the diameter of the gas port in the barrel, and the max diameter that gas blocks are drilled to - they're all drilled to 0.125" in the block, because that's the max diameter of the inside of a gas tube.  With that gas port diameter, you can easily account for the the shoulder-placement of a gas block, or spacing it 0.016" forward.  The hole in the gas block will still fully cover the diameter of that gas port, if you put it at the shoulder, or space it the 0.016" forward...

This is something that you really need to pay attention to on a 16" rifle gas barrel that has a 0.105" gas port diameter - gas block centering over the hole is pretty important in that case.  Not with your case, though.  There's enough overlap, because Big Hole in gas block will cover Little Hole in barrel, almost every time.


Pretty much what I thought.  Kinda caught me off guard they even mentioned it. 

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10 hours ago, Sharpshooter said:

Geez, you sound like something I heard a lot of years ago: big girl, big hole; little girl, all hole. So far, it's sorta proved true. :hump:

Depends on the little girl :hump:  little hole get bigger ( in my best Charlie Chan) voice

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Had all sorts of problems with my rifle.I followed all the advice 98z5v suggested and now I have a absolutely fully Functional .308Ar.

My gunsmith built me a rifle with the wrong buffer,spring and a gas port that wouldn’t run the rifle. 

Have the gas port drilled!

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