Failure To Extract

#1

I went to the range today; the sub 2k is runing pretty smooth. Able to sight it in, making it much funner to shoot. Only problems I had where screws backing out, front sight going down, and the last round not ejecting. Going to put some loctite on the screws so that’s not a problem. The failure to eject usually happen on the last round or towards the end. What can I check to fix this?

I have most of the mcarbo parts in. Do I have to much recoil management going on?

7 Likes
#2

@Pew_Ding Little confused here. Your topic is “Failure to extract” but you post about a failure to eject. Different critters here. Tell me about your ammo. Factory or reloads. Brass, aluminum, or steel cases. On extraction failures are the rounds rims getting torn? On ejection failures is the round hanging up in the ejection port sideways? Maker of the magazines you’re using?

10 Likes
#3

@Don68 I was using mac-gar magazines. Ammo was Winchester 9mm NATO 124 grain fmj, brass. The spent case would be sideways in the ejection port and the bolt would be on the case. The rim’s of the rounds are not being torn.

4 Likes
#4

@Pew_Ding Mec-Gar makes excellent mags for many gun manufacturers but I would try one that is made for that model: Smith,Sig,Beretta,CZ,Glock, which ever you have. Next I would try a standard pressure round, NATO is a little hot. What recoil reducing M*CARBO parts are installed?

7 Likes
#5

The mags work fine in the sig. I’ll change ammo and see if anything changes. I have the muzzle break, the red lifesaver buffer, and the recoilless charging handle.

4 Likes
#6

question, any drag marks on the cases in question?

6 Likes
#7

How does it run with the factory supplied Pmag? Zero issues with my stock Pmag and genuine G19 mags.

4 Likes
#8

@Wedge Sig came with 10 round mags. Only used them until I got real mags. I could test them out though.

3 Likes
#9

@GOBLIN just the case being crushed. No drag marks that I recall.

5 Likes
#10

if you shoot 7 rnds, wait a min or so, shoot the rest of the mag, does it slow eject and catch the bolt or does it cycle? reason i ask, had the same issue on a ruger mini-14 when i shot NATO

5 Likes
#11

Your S2K came with a real OEM Sig 10rd mag? If not, does it have a red follower? That’s exactly what my supplied G19 Pmag looks like.

Also, since the case is getting crushed, how’s your ejector? Sounds like it might not be kicking out the fired cased properly. If I remember right, I think it’s possible to install it backwards, which would definitely cause issues. It could be that it FTEjects on that last round because the rounds under the previous rounds are helping the cases out the ejection port. The last round doesn’t have that benefit.

5 Likes
#12

The Sub 2k I got was Baretta; swapped the mag release since it was the only non glock version available at the time. That magazine that came with the sub 2k is stamp Para. The Sig was a CA version and came with 10 round mags. So I bought mec gar mags that I use for both sig and sub 2k.

I was having an issue with the mec gar mags in the sub 2k when I filled them up all the way. With the 1st round or 2 not feeding properly. I found if I loaded 2 rounds shy of full mag capacity, the problem stopped. The same full mags worked just fine in the sig.

5 Likes
#13

@Pew_Ding one thing to check on is carbon build up just under the extractor claw. I run pretty clean federal and speer ammo but I still have to gently scrape off that crust with a flat blade screwdriver.

If left to build up it will not extract properly and casings can get “crushed” from force of bolt slaming into them.

It’s actually a pretty common issue with “blow-back” weapons. As that crust of carbon builds up under the extractor it is grabbing less and less of the rim of the spent case to pull it back over the ejector. Eventually it wont grab at all. Because it is a blowback the shell will be pushed out of the chamber but not be pulled over the ejector tab. The bolt will then cycle home and you will have a dented or crushed case.

I see the build up after 200 rounds. It is just part of my routine maintenance.

5 Likes
#14

Just checked that the ejector was facing the right direction. I’ll have to see if I can get a brush in there without taking apart.

4 Likes
#15

to me, sounds like you need to polish/ Hone the chamber, had that 14 that at 10 was fine, and by 12/14 was chopping the case with the bolt. heat would swell the chamber just enough to slow extraction, hotter it got the worse it got. polished the chamber evenly, and that issue went away.
that problem usually rectify’s itself on break in, but on some firearms, polishing will alleviate a intermittent issue.

3 Likes