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Old October 17, 2021, 08:20 AM   #1
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AR ejection port flash.

This rifle build of mine is cursed. I removed the 2nd defective Bushmaster barrel and installed PSA barrel that I've used before on other builds, is nitrided, 16 inch, 1:7, carbine length gas and comes with the A2 front sight/gas block and a delta ring. Went together well, looks great, runs great but...when testing it last night in low light, there's a huge flash from the ejection port. Ammo was a mix of American Eagle. 223 and Wolf .223.
Anderson buffer tube with Anderson carbine spring and buffer. I'm thinking it might be over gassed and I need heavier buffer but thought I'd see what the collective thinks. I'm going to put a JP Enterprises polished spring in it and was thinking of an H/H1 buffer but not sure if that's enough weight and should I just go right to H2?
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Old October 17, 2021, 11:22 AM   #2
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Sounds like it may be a little over-gassed. Maybe.

But, more likely, is that the powders used by the manufacturers just don't have flash suppressant.

Probably fine.
Don't even try it. It's even worse than the internet would lead you to believe.
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Old October 17, 2021, 02:42 PM   #3
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I have the jp spring, my factory spring got weak and I was struggling to chamber rounds. I decided to upgrade. Well worth the few extra dollars. The advice I was given on buffers was to use the heaviest buffer the gun woukd lock open on. Going to a h2 buffer may be too heavy. I would recommend a heavy buffer.
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Old October 17, 2021, 03:55 PM   #4
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You guys might have contributed to the other thread with something related to this. That fella was having a bear of a time with his AR platform malfunctioning. All the replies on that thread were great answers. Check that one out. “AR casing stuck like chuck” or something along those lines.

If the rifle is cycling correctly, yet you hare having burning gas coming out of the ejection port, overpassed is my first guess. But don’t overlook the obvious things, either. What Shadow9mm said about upping your buffer weight isn’t a bad idea, at all. It will keep that BCG in place just that split second longer to make sure the impinger is still on the gas tube, thereby minimizing the chance of the flash from coming out the ejection port. That would worry me, too. Worry about cooking off a round out of battery, etc.
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Old October 17, 2021, 09:41 PM   #5
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Does your gun do it all the time with every shot with all ammo--or you only saw this once/occassionally? If it's not all the time--my guess is that residual gases in the bore--or possibly residual powder igniting trailing the bullet--has maybe exited the chamber end upon retraction of the case by the bolt. Are you using the same ammo that caused the stuck case in the first build? I'm beginning to wonder if there might be something there?
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Old October 18, 2021, 12:38 AM   #6
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Before I put any effort into chasing moving goal posts,
you need to remove the variable of Russian or unknown ammo.
Sure,an AR might run with all sorts of ammo.

Its just not reasonable to have expectations of a direct impingement gas operated rifle while running generic ammo.

How does it run on US GI ball or equivalent? Or good handloads with known components?

You are going to have to develop a way of understanding how the thing works,and eyes and a mind to see details.

Did you get the nut indexed right so the BCG telescopes over the gas tube on center. You have gas rings on your bolt. Are they clean and in good shape? What about the bore in the BCG? Carboned up? Maybe it just needs to break in.

If you have no choice but to shoot garbage ammo,OK. Tough times. Lower your expectations and just shoot it.

Find some Lake City or IMI or Black Hills. Shoot a couple hundred. See how it does.

An H-2 buffer is as easy to try as anything you can do. Boldly try it! See what happens.

FWIW,many folks know the AR carbines made to spec are inherently over gassed. Comes with the territory. Thats why the Kool Kids say "Overgassed" a lot.
I.myself,do not build a 16 in carbine with a carbine length gas system. I go mid. I like the extra real estate with the forend. And I use a Midwest or other free float forend. I prefer a free float forend .
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Old October 18, 2021, 05:45 AM   #7
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All good questions. Yes, barrel nut is indexed correctly, gas tube is centered. Have not tried any other ammo, will try other brands and see how it goes. BCG is new, new barrel, so everything is still breaking in.
Lockup seems to be good and the gun runs great, there's just a surprisingly good bit of flash out the ejection port. I'm still leaning towards overgassed plus cheap ammo. The better quality JP spring and a Noveske H1 buffer are ordered, will be here in a few days, will try that and report back.
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Old October 18, 2021, 07:52 AM   #8
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Just an opinion as I've never seen it on our AR but I've never really looked. Ammo does make a big difference on the flash out the muzzle and I could believe it might make its way thru the port.

It's extremely noticeable with the "custom" match ammo we use in our pistols (9mm) - it looks like they are spitting fire. Not an AR, but shows what a difference ammo (and whatever it's loaded with) can make.

If it's only with that one type, then I wouldn't give it another thought.
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Old October 18, 2021, 06:01 PM   #9
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I will second the cheap ammo comments. Wolf type steel cased is as made as cheaply as possible.

Please, Let us know if the stronger recoil spring and heavier buffer helps.
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Old October 19, 2021, 12:39 PM   #10
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Anytime you notice anything unusual that is related to ammunition, the first step in testing should always be to see if what happened also does it the same way with other ammunition.

if it is consistent across all brands of ammo, then its something to do with the gun. If its not, then it's something about the specific ammo used.
All else being equal (and it almost never is) bigger bullets tend to work better.
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Old October 19, 2021, 02:31 PM   #11
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Some steel cased ammunition will allow gas to escape around the cartridge.
I’ve seen some Russian steel cased ammunition crack the casing.
Both of those instances, I’d assume could cause a visible flash around the bolt.
Also, the gas exhausts through the carrier under normal operation. So I’d think over gassed may cause it too.
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