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BCG Jamming next bullet into feedramp

jayhitek

jayhitek

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Hello,

Having a problem here..
If I put in a full magazine and pull the charging handle. First bullet loads fine and shoots.
Shell casing ejects and the next bullet to load gets jammed at an angle from the follower on the magazine into the feed ramp with the Bolt Carrier Group rammed half way into the bullet.
I then sometimes can't pull the charging handle back to free the BCG, so I have to drop the magazine, pull the charging handle and pull the round out.

The jammed bullet usually has a good dent in the middle of it. Or will have a nice drag dent on it. All from the bottom tooth of the bolt.

If I clear the jam, reinsert magazine, charge and fire, all good. but Next round is once again jammed.

I've tried about 10 different magazines (all preban of different sizes and metal and plastic)
This happens about 90% of the time. Occasionally will I be able to fire more than 2 rounds at a time without the jam.

So is the BCG coming back into battery too fast and my buffer tube spring too soft? too strong?
Is the tooth of the Bolt not bringing the next round into the barrel from the magazine properly?

It was working fine a couple of months ago. with maybe only a couple of these FtF jams.
Then the last two times out.. Happening more and more. So that's why i brought like 10+ different magazines to see if that was the problem. And yesterday was brutal. 90% failures.
I haven't cleaned the gun in a little while. But it's only been a couple hundred rounds. So not that dirty.
Ammo is Federal Eagle 223 55g
And I have not tried cleaning it yet to see if that makes a difference.

BCM Upper Rec M4, Anderson BCG, Daniel Def M4 556 barrel, CMMG Gas tube, Brownells AR-15/M16 MIL-Spec Buffer Tube Assembly
Lower is Spikes Multi

Any help would be appreciated.
Thank you,
Jay
 
That's actually a good idea to start the trouble shoot process.. I could try a BCG from a Colt upper I have. Swap those out in the upper. Could narrow down if anything is up with Anderson BCG itself.. Like the gas key.
 
1. One cartridge in mag insert mag charge rifle and shoot. Does your bolt stay locked open?
2. Think of anything you touched recently ?
3. can you duplicate the jam by running the charge handle ?
4. what mags are you using. hows your mag catch?

Generally when the bolt half feeds a round like that its a mag or short stroke issue.
make sure the gas block is tight and aligned and pull your bolt and check the gas rings.
Anderson is generally ok but we have no idea where they get other parts like gas rings. I know several people now with discount BCG that the gas rings come out in pieces after just a few hundred rounds.
 
Last edited:
Yes stays locked open.
Nothing out of the ordinary
I'm going to try that tonight with snap caps
all different pre ban mags. From Okay to Colt to plastic Orlite. 20 to 30 rounds. They work in another AR I have without issue.

I'll check the BCG tonight.
 
jayhitek said:
Yes stays locked open.
Nothing out of the ordinary
I'm going to try that tonight with snap caps
all different pre ban mags. From Okay to Colt to plastic Orlite. 20 to 30 rounds. They work in another AR I have without issue.

I'll check the BCG tonight.
Click to expand...
check your gas system from end to end....pull your buffer and spring just to make sure nothing strange going on in there. Again a friend bought a heavily discounted buffer and the little end cap broke and had parts floating around in the buffer tube.
 
Alrighty.. I cleaned the AR thoroughly. It was pretty dirty.
Gas tube looks good and still lined up. Buffer tube also looked good.
I cycled 4 snap caps through it fast and it loaded and ejected flawlessly.

Except! I did get it a couple of fails when I was slow and weak on pulling the charging handle and not coming back with the bcg at full speed.
So that being said, if it does fail with live ammo it's because the bcg is not coming back fast enough or going all the way back into the buffer tube.. And can't pick up the bullet to load properly.

When I test it at the range, And if I get the same bullet jams. I'll start by swapping the lower to test the buffer spring from another gun.
Then work my way to swapping out BCG's and see if that is sole problem.

Hopefully its all a part that i can swap out to narrow down. Cause if all of that doesn't work.. it could be the gas tube and that requires a lot more taking apart and break down etc.
 
Did you pull you bolt apart. Check your gas key tightness and gas port.
Slow charging or riding the charge handle just creates problems.
 
mac1911 said:
Did you pull you bolt apart. Check your gas key tightness and gas port.
Slow charging or riding the charge handle just creates problems.
Click to expand...

I did check it. Looked fine. But won't know for sure until I test it out or swap it for another one anD see what happens.
 
Testing it out now. It's working flawlessly. Looks like a good cleaning did the trick with regards with a bullet getting jammed.

But, the bolt is not staying open on last round..

What could cause that?
 
The bolt not holding open Happening on both guns..
Except the colt, the next bullets are clean.
Probably just because I've been running the other ar more.
 
Ok. It ran fine for a while. I put it down to work on other stuff. Then FtF started happening again.

Ran out if time to figure out out what is wrong.
Here is a slow mo video of it not picking up next round.
Didn't get video of it jamming 2nd round when that happened. (it was hard to shoot left handed and then video righty)


View: https://youtu.be/yH3QiclSHVM



View: https://youtu.be/-6H0SfZWFls
 
It happened with old adventure line, usgi, orlite, and Thermold.

But the tops of the Orlite even the new ones look like that. Plastic..
 
Bolt not locking back on empty, and not stripping next round from mag (given that that mag is good, and full power ammo are used) are both signs of a under-gassed gun. Look for gas block out of alignment over gas port, loose gas block, gas tube loose in gas block, too heavy of recoil system (buffer and/or spring) or a combination of non-compatible parts.
 
SJan said:
Bolt not locking back on empty, and not stripping next round from mag (given that that mag is good, and full power ammo are used) are both signs of a under-gassed gun. Look for gas block out of alignment over gas port, loose gas block, gas tube loose in gas block, too heavy of recoil system (buffer and/or spring) or a combination of non-compatible parts.
Click to expand...


The ammo is AE 223 55 grain.
I have some Wolf Gold I shot with it before.
I'll see if any difference with that.

I looked at the gas block and it looks lined up. I'll see if I can get the hand guard off and do a better inspection.

I wonder if I'm Using the wrong buffer and spring with it?
Maybe you're right and too heavy?
 
mikelawtown said:
Don’t cut any springs but first of all that magazine looks beat up
Click to expand...
Funny, you guys don’t think twice about stuffing the lowers and uppers with parts from every where but one manufacturer, and then are afraid to fine tune all the mis matched to each other parts.o_O
 
W.E.C said:
Funny, you guys don’t think twice about stuffing the lowers and uppers with parts from every where but one manufacturer, and then are afraid to fine tune all the mis matched to each other parts.o_O
Click to expand...

It's called Mil-Spec :)
You don't fine tune an AR by cutting springs especially a buffer spring, I have tried many diff springs just to "Fine tune" and they always worked and never will a spring make an issue with a carbine setup if made for it unless it has 20k rounds on it and worn. I had a M&P sport with a PSA Prem BCG and it did the same, 2nd round wouldn't pickup and after replacing it with the AIM NIB it runs flawless. PSA BCG was sent back and the report was the BCG was out of spec. Switch the BCG from your other one 1st. Where r u loc?
 
Last edited:
mikelawtown said:
It's called Mil-Spec :)
You don't fine tune an AR by cutting springs especially a buffer spring, I have tried many diff springs just to "Fine tune" and they always worked and never will a spring make an issue with a carbine setup if made for it unless it has 20k rounds on it and worn. I had a M&P sport with a PSA Prem BCG and it did the same, 2nd round wouldn't pickup and after replacing it with the AIM NIB it runs flawless. PSA BCG was sent back and the report was the BCG was out of spec. Switch the BCG from your other one 1st. Where r u loc?
Click to expand...
Or if you want to make it run without spending any more money, and keep replacing random parts till you get to a combo that works, cut the spring.
 

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