CMMG 5.7 double firing

[Larry B]

New 5.7 Banshee pistol with 20 rounds fired and it started double firing. Contacted CMMG and so far no response. Anyone have similar issues?

[Armed Eye Doc]

Welcome to the forum.  @Larry B

I don't think anyone here has a 5.7 Banshee.  I have an FN and AR57 but that is all that I know of here.  If you don't hear from CMMG, I would visit a 5.7 specific forum like https://fnforum.net/forums/fn-five-seven/#/forums/34?page=1 or www.fivesevenforum.net.  You likely to get a more informed answer there.  You can also try asking this guy.  https://eliteammunition.com/. He is a custom 5.7 ammo manufacturer that also works on guns.

If you find an answer, share it with the group.  It may cross over into one of the other Banshee platforms.  Information is always a good thing to have.

Edited June 5, 2020 by Armed Eye Doc

[Radioactive]

I have heard of feeding problems related to mag issues but not a double fire. I almost picked up a 10mm banshee last feb but decided to pass on it for some reason but I don’t remember what it was.

[98Z5V]

1 hour ago, Larry B said:

New 5.7 Banshee pistol with 20 rounds fired and it started double firing. Contacted CMMG and so far no response. Anyone have similar issues?

It's BCG speed - that thing is going so fast, and so hard from the power of that little stinger 5.7, that the disconnector can't even catch the hammer.  Oh, make no mistake, it fully cycles that buffer all the way into the end of the receiver extension, and probably feels like it has some decent "kick" to it.  That BCG is going so fast that the disconnector can't get ahold of the notch in that hammer and stop it.  The hammer then follows the BCG, and when the BCG chambers the next round, the hammer is right there to let it fire.

If you held the trigger to the rear after every shot (proper trigger follow-through), it still might do it once in awhile, but definitely not as often.  Proper trigger follow-through would stop most of that doubling - but not all of it.   Most of your doubles are probably coming from trigger discipline. 

I went through this with my .45AR.  You need a WAY STIFFER recoil spring, and a WAY HEAVIER buffer. 

You haven't said a thing about the specs on those two items yet, though.

Go rip up the Intro Section, and tell us about yourself.  It's right here:

https://forum.308ar.com/forum/22-introductions/

Edited June 5, 2020 by 98Z5V

[Armed Eye Doc]

I was surprised, but the buffer in my AR57 is only 4.85 oz.  The BCG is 12.4 oz though.  I didn't think to check the spring and I'm too lazy to go back into the safe.