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cjd3
30 August 2015, 20:31
After todays range trip, I had a whole slew of malfunctions with my rifle build. I will try to get some photos up later this evening, but here is what is happening:
First off, I'm having a hard time seating the magazine with the bolt closed. I have 3 G2 Pmags, happens to them all.
Secondly, if I load the rifle with bolt open, I will be able to shoot 2 rounds. The 3rd one clicks. Upon extraction of the bullet, small to moderate effort to pull the charging handle back, the brass has 2 gouges on the top and the primer isn't touched, so I can assume I am not achieving full battery. I'm thinking this is from the bolt closing on top of it while chambering the last round that fired.
One of my malfunctions jammed a round in the feed ramp (M4) resulting in bullet setback.
So I've got a bit of a mystery for me here. This never happened with my factory Stag.
The lower is a Blemished San Tan Tactical with a CMT UPUR-1LH on top. There is a little wobble from the STT lower that doesn't exist when the upper is mated to one of my other forged lowers. I do have an adjustable gas block, which I will open all the way up next session. I am using a heavy buffer, and the barrel is an 18" SPR with a rifle length gas tube.
Thanks for the help. Once the kids are fed and in bed, I can get some pics up.

Thompson
30 August 2015, 21:29
Seating the mag on a closed bolt - fully loaded mag? If so, that's not uncommon.

Maybe this is a stupid question - did you check headspace?

Farva
30 August 2015, 22:05
Seating the mag on a closed bolt - fully loaded mag? If so, that's not uncommon.

I agree. I have this issue as well on occasion, just gotta give the mag a love tap [bash]

WHSmithIV
30 August 2015, 23:00
I agree. I have this issue as well on occasion, just gotta give the mag a love tap [bash]

My magpul fully loaded mags don't like to seat fully in with my Phase 5 billet lower either. So, I just slam them in and that works. My hexmags work better than that for insertion and so do my two Israeli military surplus mags.

As for the bang, bang, click... that could be a few things. How many rounds have been fired so far? Where are the gouges on the casings? With rifle length gas and an 18" barrel there's no need to bleed gas off at the gas block.

cjd3
30 August 2015, 23:37
http://i.imgur.com/2bQVycP.jpg
This rifle has around 100 rounds through it. This is the first time I've had this much of a problem, and there was little change from my last trip to the range.
So the Pmags are loaded to 29. But fired 29-28, click on 27. Clear, free 26-25, click on 24. I thought I gave it a good love tap, but apparently not.

Farva
31 August 2015, 00:26
you said on the clicks there was no primer strike correct?

cjd3
31 August 2015, 00:58
you said on the clicks there was no primer strike correct?
Yup, or a very light tap. I'm thinking it was just millimeters out of battery.

Farva
31 August 2015, 01:33
ammo issue maybe? maybe got a bad batch.

mustangfreek
31 August 2015, 02:55
ammo issue maybe? maybe got a bad batch.

Im not a whole lot of help , but have had some troubles lately with my crap that had and still..Anyways

Curious what kind of ammo factory stuff? or reloads?

Bcg and bolt?

got any other mags to play with? some GI's, gen 3's , lancers something else to try for the hell of it?

Im just spit balling

those are some good ones, ramps crushed them suckers..

Farva
31 August 2015, 03:22
Every now and then on a new build Ill have new feed ramps/ new extractor scratch some casings until they break in but nothing close to this

Kopis
31 August 2015, 09:47
i had this exact issue with one of my previously reliable builds. It started after i installed a CAA Completely Collapsible Stock (like the Troy PDW stock). It had a proprietary BCG with integrated buffer and a provided spring. I ended up going back to a minimalist stock and JP SCS and havent had an issues since. I would look at the gassing or buffer/spring. I think i could have gassed mine up more but i just cant stand a finicky gun.

Former11B
31 August 2015, 11:37
Those two little pinch marks on the brass are really suspect. And that's from just inserting the mag? Is the bolt forward at the time? It almost seems like it's out of battery and the brass is hitting the lugs on the bolt itself

Stone
31 August 2015, 12:04
That is the bolt dragging across the round. Back your mags down to 25 rounds and see if it will cycle. Rifle well lubed? On new builds I hand cycle them at least 50 times to get things mating together. Since the bolt is dragging it's slowing it down and not going into battery on that third round. Definitely open up that gas block as well.

Jerry R
31 August 2015, 12:35
http://i.imgur.com/2bQVycP.jpg

Are these reloads?

Look at the shoulder set-back - the ridge formed right at the beginning of the taper down to the neck. I have not seen a rifle set the shoulder back like that - bullet set-back yes, but not the shoulder. They appear to be reloads done with the sizing die set incorrectly; i.e., the die is literally crushing the case shoulder. With that wrinkle, they will not chamber easily, if at all. They would stop short, eliminating the possibility of proper primer strike.

Compare these to rounds out of the same batch that have not been chambered - how does the shoulder look? If the rounds are factory, and the shoulders on un-chambered rounds look good, then pursue options stated above.

The parallel creases in the case body look like lug impressions - either the rounds do a nose up, don't chamber, and the bolt carrier forces the bolt lugs into the case, or the nose fails to chamber and the carrier jams them into the barrel extension lugs. Can you tell if those two creases are on the top of the case when you eject them, or on the bottom of the case?

Based on your loading of the magazines, are the "clicks" always when feeding a round from the same side, or does it happen when feeding from either side? Perhaps barrel extension mis-aligned??

alamo5000
31 August 2015, 17:23
The lower is a Blemished San Tan Tactical with a CMT UPUR-1LH on top.

Which BCG are you using?

Former11B
31 August 2015, 18:40
Are these reloads?

Look at the shoulder set-back - the ridge formed right at the beginning of the taper down to the neck. I have not seen a rifle set the shoulder back like that - bullet set-back yes, but not the shoulder. They appear to be reloads done with the sizing die set incorrectly; i.e., the die is literally crushing the case shoulder. With that wrinkle, they will not chamber easily, if at all. They would stop short, eliminating the possibility of proper primer strike.

Compare these to rounds out of the same batch that have not been chambered - how does the shoulder look? If the rounds are factory, and the shoulders on un-chambered rounds look good, then pursue options stated above.

The parallel creases in the case body look like lug impressions - either the rounds do a nose up, don't chamber, and the bolt carrier forces the bolt lugs into the case, or the nose fails to chamber and the carrier jams them into the barrel extension lugs. Can you tell if those two creases are on the top of the case when you eject them, or on the bottom of the case?

Based on your loading of the magazines, are the "clicks" always when feeding a round from the same side, or does it happen when feeding from either side? Perhaps barrel extension mis-aligned??

Good catch on that shoulder issue. Looking at the brass more closely, it looks like the one on the right also has a small crease down where the sizing die stopped. I've had my small base die do that to a piece here and there (usually brass on 4+ loadings) and I toss it because it would prevent proper chambering

cjd3
31 August 2015, 19:38
Are these reloads?

Look at the shoulder set-back - the ridge formed right at the beginning of the taper down to the neck. I have not seen a rifle set the shoulder back like that - bullet set-back yes, but not the shoulder. They appear to be reloads done with the sizing die set incorrectly; i.e., the die is literally crushing the case shoulder. With that wrinkle, they will not chamber easily, if at all. They would stop short, eliminating the possibility of proper primer strike.

Compare these to rounds out of the same batch that have not been chambered - how does the shoulder look? If the rounds are factory, and the shoulders on un-chambered rounds look good, then pursue options stated above.

The parallel creases in the case body look like lug impressions - either the rounds do a nose up, don't chamber, and the bolt carrier forces the bolt lugs into the case, or the nose fails to chamber and the carrier jams them into the barrel extension lugs. Can you tell if those two creases are on the top of the case when you eject them, or on the bottom of the case?

Based on your loading of the magazines, are the "clicks" always when feeding a round from the same side, or does it happen when feeding from either side? Perhaps barrel extension mis-aligned??

I just noticed the mushroom shoulder. These are once fired 223 PMC brass, glad I've been reloading matching head stamps too, I'll look into that batch further. I don't seat and crimp in the same die anymore, and this is the first time I've run into that problem since. Last time that happened, they were very difficult to eject, and the bolt didn't even come close to closing.


Which BCG are you using?
It's a Stag chrome lefty BCG, so i'm kind of limited.


So, tonight I clean, lube, and cycle. I'll pull these bullets and reload dummy rounds, to see if I can recreate the problem.

Eric
1 September 2015, 06:36
Clean, to include hitting the chamber with a chamber brush, lube and test fire with factory brass cased ammo. If problems persist, confirm proper assembly and spring orientation in the FCG. Improper hammer spring orientation causes light primer strikes.

http://img.photobucket.com/albums/v503/AR15forme/FCG.jpg (http://smg.photobucket.com/user/AR15forme/media/FCG.jpg.html)

Jerry R
1 September 2015, 08:39
I just noticed the mushroom shoulder. These are once fired 223 PMC brass, glad I've been reloading matching head stamps too, I'll look into that batch further. I don't seat and crimp in the same die anymore, and this is the first time I've run into that problem since. Last time that happened, they were very difficult to eject, and the bolt didn't even come close to closing.

Excellent ! I think we might be on to something. If other cases have the same wrinkle, one of the dies is set incorrectly. Could be the Resize/DeCap, seating die, or the crimp die (unless you are way over-crimping, probably not the crimp die) Easy mistake to make on the seating die, specially if it was once used to crimp (your comment "anymore"). Back it off so that nothing touches the case body, only use the seating stem to place the bullet at the proper depth. Sizing die should be only deep enough to take a little of the slack out of the shell holder/shell plate when the handle is fully down. A case gauge is an excellent investment for each caliber. Will instantly let you know if the cases are sized enough - or too much. They will accept loaded ammunition also. Cheap insurance. Around $20 at Midway USA.

http://www.midwayusa.com/product/268983/lyman-case-length-headspace-gage-223-remington?cm_vc=ProductFinding

Eric
15 September 2015, 16:44
Resolved?

cjd3
26 September 2015, 14:16
So here is what i found. Checked the headspace with my new Go/NoGo gauges. and it checks out just fine. I ran the remainder of my built rounds through an EGW 7 round chamber checker. There all dropped in nicely, with only 2 problems. One was a mangled case that should have been culled, and the other had a primer that wasn't seated all the way. No collapsed shoulders in the bunch, so it doesn't look like I have a problem with my seating die. So i think the problem lies in the lower, ever since I received it, there was a lot of slop with the pivot and take down pins. I pulled that lower off, then transferred all the parts to my new lower I was going to use on another build. It was solid. Using my snap cap rounds, I am able to seat the magazine, bolt closed with no problems. No cycling problems either with them. When I get the rest of my lower parts. Another thing i've noticed, is that the bolt stop has a much bigger gash across it than my other rifle, which has a lot more rounds through it. So I really think that's the problem. I may have some range time tomorrow, and I'll follow up with the last of the checked ammo. On a side note. If anyone needs headspace guages, I'll lend them out, as long as you pay shipping both ways. In a padded envelope, it's only a few bucks.

Here's a pic:

http://i.imgur.com/bVyadbK.jpg

cjd3
4 October 2015, 17:49
Range report from today. I removed all everything from the other lower and put in my new Aero Forged lower. I also opened the gas block all the way up. All three mags I brought would seat with the bolt closed. Everything cycled smoothly. Every round went bang, and the only click I got was the bolt closing on the first rounds. All spent brass looked normal. It was a great malfunction free day. Do you think the lower gap that was present with the other lower cause these feeding problems?