View Full Version : Diagnose malf
What causes this? It's happened twice in the past 1K rounds.
Happened on reload from bolt catch
Okay Surefeed loaded to 28 rounds
Geco 55gr (Swiss)
Daniel Defense barrel
Colt BCG
Aero or BCM upper receiver
VLTOR A5 kit
LMT lower
https://photos.smugmug.com/ARs/i-c9xbXx5/0/5ef2b9a7/X3/85FB8B06-B026-4E79-8D00-8F4277180CB5-X3.jpg
Do you know if it was the same mag both times?
My guess is a magazine issue, like the feed lips aren't retaining the rear portion of the cartridge properly as the bolt comes forward to strip it out of the mag, leading to the round being misaligned as it's pushed toward the chamber. However I don't have even a fraction of the malfunction-diagnosing experience of many members on this site so I'm more interested in what they have to say on the matter.
Do you know if it was the same mag both times?
My guess is a magazine issue, like the feed lips aren't retaining the rear portion of the cartridge properly as the bolt comes forward to strip it out of the mag, leading to the round being misaligned as it's pushed toward the chamber. However I don't have even a fraction of the malfunction-diagnosing experience of many members on this site so I'm more interested in what they have to say on the matter.
This, most likely.
Coal Dragger
08-25-18, 18:01
Time to number your magazines if you haven’t already. Write down the magazine number when you have a malfunction, then plan on fixing or ditching that magazine.
At the range when I have an obvious mag caused issue, I stick a round in it backwards and throw it in the range bag.
Easy to keep track of.
I am guilty of not numbering these mags. I starting using this group of ten in November and they've shot up a little over 3K rounds. I've had a few double feeds, but not where the case was backed out of the ejection port.
The buffer spring is the original VLTOR and has probably 6K on it.
Okay Surefeeds are generally pretty decent, probably the best GI aluminums as far as I know. You may have one or more iffy mags though from the sound of it.
You can try taking your buffer spring out of the receiver extension and measuring it to see if the length is still in spec.
For a carbine spring it's in spec if it's between 10 1/16" and 11 1/4", unless for some reason it's different for the VLTOR. Your problem doesn't sound like anything to do with the buffer spring to me though, but after 6k rounds there's no harm in checking it.
Feedlips measure about .438" across with no visible defects.
This one is hard to pull bolt out of battery. I don't know if that could indicate something else.
I've had a few double feeds, but not where the case was backed out of the ejection port.
You say double feed, is there another round in there someplace that we (at least 'I') cant see?
Did a round fall out through the magwell when you removed the mag?
What followers are in the mags? The grey one's?
I've had a few double feeds, but not where the case was backed out of the ejection port.
What do you call a double feed? If by double feed, you mean the rifle tries to feed two or more rounds from the magazine at the same time, that's a magazine problem. Toss the mag and replace it with two new ones.
True to life double feed.
I locked the bolt back and ripped out the mag and there was three live rounds on the ground.
This has always been from a bolt locked back reload. No chance of FTExtract.
Ah, I just thought you just had the top round in the mag going screwy when you hit the bolt release.
I still vote magazine issue though. To my understanding double/triple feeds are nearly always mag related.
Try to figure out which mag(s) it happens with, and ditch them. Don't try to fix them, mags are too cheap right now to even bother trying to salvage a problem one. Dispose of them with extreme prejudice.
True to life double feed.
I locked the bolt back and ripped out the mag and there was three live rounds on the ground.
This has always been from a bolt locked back reload. No chance of FTExtract.
So while your not sure that it is the same mag - you are using a group of ten and it has happened twice in about a thousand rounds. I'd vote for the bad mag also, theory being you just cycled through them to get to it again.
The other thing that you might possibly be doing is being a little too vigorous when you are inserting the mag with the bolt locked back and noticing that it puked a couple rounds out into the receiver.
How often do you clean and lube your rifle? I can't recall the last time I had a double feed with the rifle I shoot the most, I'd be concerned if I'd had as many as you reported in 3,000rounds.
In any event, I'd give it a good cleaning, look for any signs of unusual wear and see if that takes care of your hard to cycle out of battery issue.
Good luck!
Apparently the vigorous reload is the problem. I just loaded the mag to 30 rounds and tried about 20 times to get the double feed, never happened. Slammed it in and it puked a round out and had the case head of the top round out of the mag, hit the bolt release and all three birdnested in the upper.
Tried the other ten mags, they'll all do it with about the same force. Sure seems like it's easy to get a malf though.
Unless you are really slamming 'em in there that still sounds like the mags are a little off to me. I've tested my Okays by physically slapping the bottom of their floor plates while loaded and haven't had rounds shift like you describe.
Do you have any other mags you can try to duplicate those results with, like a Pmag or something?
No but I realized that the 69grSMKs in one mag wouldn't do it so I loaded a couple with those and sure enough, wouldn't do it.
Only thing I can think of is that the Geco is so polished and smooth it's easy to get one to spit out of the magazine.
Apparently the vigorous reload is the problem. I just loaded the mag to 30 rounds and tried about 20 times to get the double feed, never happened. Slammed it in and it puked a round out and had the case head of the top round out of the mag, hit the bolt release and all three birdnested in the upper.
Tried the other ten mags, they'll all do it with about the same force. Sure seems like it's easy to get a malf though.
Are you slapping the bottom of the mags to seat them?
I see people do that with rifle and pistol and best case scenario, its slow.
Worst case, you get multiple rounds in the chamber. Just saw a guy do this at a pistol match yesterday.
If not, something is up, seems like youd really have to try to do that just feeding the mag in.
Two potential issues. Either you are slamming the mags too hard or the feed lips are worn, or maybe it's both. Have you tried to use the push/pull method? Is there a reason why you are slamming them so hard into the lower?
I grab the mag like a beer can, never by the bottom of the mag.
I didn't think I was slamming them home that hard, it only caused a malfunction twice in 1K rounds of live fire. It didn't do it a lot until I started trying to identify bad mags.
I suppose it's possible that forcefully inserting a mag into the rifle with the bolt locked back could cause a just slightly iffy mag to manifest problems more readily than it would if you just did the "smack it on the floorplate" test. When you hold a mag in one hand and smack the bottom with the other, there is still some "give" by the hand holding the mag.
In theory, if you are slamming a mag into the gun however, you are acting against its weight, if the bolt is locked open, the inertia of the gun means that mag is coming to a relatively abrupt stop, the cartridges inside are going to keep going however unless something stops them - ideally the feed lips on the magazine. if the feed lips on the magazine are flawed somehow it could be allowing the cartridges to shift when the mag comes to that abrupt stop, just enough to cause you problems when you hit the bolt release after your reload.
If the mag is slightly iffy, it's only iffy with the Geco and all 13 I tried are iffy.
titsonritz
08-27-18, 21:10
I grab the mag like a beer can, never by the bottom of the mag.
I didn't think I was slamming them home that hard, it only caused a malfunction twice in 1K rounds of live fire. It didn't do it a lot until I started trying to identify bad mags.
Move on.
The problem did show itself three more times in one day of training which was about 500 rounds.
Problem has been 100% resolved with Gen M3 Pmags.
I think I'm done with aluminum mags. Totally done. Don't even want one around anymore.
I think I'm done with aluminum mags. Totally done. Don't even want one around anymore.
Would you like my address, I'll pay shipping.
Would you like my address, I'll pay shipping.
I'll send you all of 'em for $6/mag.
I'll send you all of 'em for $6/mag.
Sorry, I should have used a :) thingie to let you know I was hoorahing you.
I have a enough 'USGI' mags to last me thanks to various scares. Never jumped on the Pmag bandwagon as a result. I do have some TangoDown ARC's from Christmas a while back.
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