AR9 ejection port flash when shooting suppressed

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PisgahPlinker

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Yesterday was the first opportunity I had to put in significant trigger time with my CMMG 5 inch banshee since I have had my CGS mod9. It’s shot fine, perfectly reliable and was a dream with 150gr syntech however on several occasions I noticed a fairly substantial flash from my ejection port. What gives? Heavier buffer necessary? Like I said it’s shot great so I am hesitant to start tinkering but if it is some thing as simple as a buffer swap I would consider experimenting. PFA

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I thought that CMMG went with a radial delayed blowback. No idea how to tune that, but it does seem that it needs it.
 
Yes it is radial delayed. I’ll give em a call, just thought I’d do a little internet sleuthing first and see if anyone here had similar experience
 
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In shooting my own blowback AR9 with reloads and not suppressed I've had some flash come out the ejection port when using 147 grain and slower powder.
 
Heavier buffer is cheap and easy to try out

I don’t remember the exact weight but I know my AR nine has a crazy heavy buffer
 
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I also have an extra heavy buffer in mine, but I don’t know if you tune a radial delayed gun the same as a straight blowback. Please let us know what CMMG says.
 
Not sure what part of Charlotte you’re in, but I do have some heavier ones here (on the Charlotte/Huntersville border) you could try if you don’t already have one.
 
PisgahPlinker said:
Yesterday was the first opportunity I had to put in significant trigger time with my CMMG 5 inch banshee since I have had my CGS mod9. It’s shot fine, perfectly reliable and was a dream with 150gr syntech however on several occasions I noticed a fairly substantial flash from my ejection port. What gives? Heavier buffer necessary? Like I said it’s shot great so I am hesitant to start tinkering but if it is some thing as simple as a buffer swap I would consider experimenting. PFA

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Did it do this with different brands of ammo?
 
All of my ar9's shooting subsonic intermittently flash out of the ejection port with suppressor attached. Fiocchi 158, Fed 147, blazer 147. Seems more frequent with 158gr, worst on my 5", less frequent on 8.5", slightly less on 10.5" all have 7.7oz weights, 10.5" has "extra power pcc spring", not really sure if it makes much difference at all. All 3 run just fine with/without a can so I've just taken it as it is.

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