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Posted: 12/29/2012 5:53:25 PM EDT
What would cause this, one of my 6920's does this every time I barely set it down. It's frustrating at the range, when you have to clear and set it on the rack. I have to pretend I'm setting it on an eggshell to keep it from closing. What part is worn out, what do I need to replace?

And no, this is not my piggy fat AR.
Link Posted: 12/29/2012 5:54:27 PM EDT
Bolt release and spring
Link Posted: 12/29/2012 5:54:39 PM EDT
Normal.

Link Posted: 12/29/2012 5:56:32 PM EDT
If you are setting it down on its left side,

If not, replace bolt catch is my bet.
Link Posted: 12/29/2012 5:56:53 PM EDT
[Last Edit: 12/29/2012 5:59:03 PM EDT by CCW]
Originally Posted By HKgnnr:
Bolt release and spring


This. And make sure you have not beat the shit out of the bolt catch/release dryfiring the lower.

AR-15 / Troublshooting Forum might be the better place for the OP question.
Link Posted: 12/29/2012 5:58:05 PM EDT
Originally Posted By Rotors-R-Cool:
If you are setting it down on its left side,

If not, replace bolt catch is my bet.


placing in a rack buttstock down.
Link Posted: 12/29/2012 5:58:19 PM EDT

Originally Posted By rebel_rifle:
Normal.


He's been doing the military thing for a while, he probably knows what is normal and what is abnormal.
Link Posted: 12/29/2012 5:58:44 PM EDT
Originally Posted By CCW:
Originally Posted By HKgnnr:
Bolt release and spring


This. And make sure you have not beat the shit out of the bolt release dryfiring the lower.



Don't dryfire without caps.
Link Posted: 12/29/2012 5:59:40 PM EDT
Happens on every AR I own. It is normal.
Link Posted: 12/29/2012 6:00:32 PM EDT
It's normal. Anything that takes the tension off of the bolt catch will release the bolt to go forward. Just the inertia of putting the rifle down butt first will be enough to cause the BCG to travel back a minuscule amount, thus removing the tension holding the bolt catch in place.
Link Posted: 12/29/2012 6:00:38 PM EDT
Originally Posted By Aiden:
Originally Posted By CCW:
Originally Posted By HKgnnr:
Bolt release and spring


This. And make sure you have not beat the shit out of the bolt release dryfiring the lower.



Don't dryfire without caps.


I think he meant dropping the hammer with the upper off the lower. The hammer will hit the bolt catch.
Link Posted: 12/29/2012 6:01:23 PM EDT
Originally Posted By DamascusKnifemaker:
Happens on every AR I own. It is normal.


It's the only one I own that does that, and I own a few. The rest will release if I slam the butt down, but this one does it witn minimal pressure...I could thump it with a finger and it will release.
Link Posted: 12/29/2012 6:02:31 PM EDT
press your thumb against the small part of the bolt catch until the rifle is settled. then you can slam it in the rack as hard as you want
Link Posted: 12/29/2012 6:03:26 PM EDT
Originally Posted By Rotors-R-Cool:
Originally Posted By Aiden:
Originally Posted By CCW:
Originally Posted By HKgnnr:
Bolt release and spring


This. And make sure you have not beat the shit out of the bolt release dryfiring the lower.



Don't dryfire without caps.


I think he meant dropping the hammer with the upper off the lower. The hammer will hit the bolt catch.


I did that about 1000 times to break in the trigger, but had my thumb or some wood in there to keep from impact.
Link Posted: 12/29/2012 6:04:02 PM EDT

Originally Posted By Aiden:
Originally Posted By DamascusKnifemaker:
Happens on every AR I own. It is normal.


It's the only one I own that does that, and I own a few. The rest will release if I slam the butt down, but this one does it witn minimal pressure...I could thump it with a finger and it will release.

Yeah I think folks are missing the "barely" part in the op. like the others above said, maybe the spring and bolt release need replacing. Should be a quick fix.
Link Posted: 12/29/2012 6:04:54 PM EDT
Take a look at it and see if anything looks fubar.
Link Posted: 12/29/2012 6:07:01 PM EDT
"Barely" is quite the subjective term in this context.
Link Posted: 12/29/2012 6:07:07 PM EDT
Originally Posted By Aiden:
Originally Posted By DamascusKnifemaker:
Happens on every AR I own. It is normal.


It's the only one I own that does that, and I own a few. The rest will release if I slam the butt down, but this one does it witn minimal pressure...I could thump it with a finger and it will release.


The brand new Colt M4 select fire I was issued as a duty weapon did this also. You can change the bolt release and put in a heavier spring (provided you can find one that fits in the hole) and it should help.
Link Posted: 12/29/2012 6:07:27 PM EDT
Originally Posted By LCPL4ever:

Originally Posted By Aiden:
Originally Posted By DamascusKnifemaker:
Happens on every AR I own. It is normal.


It's the only one I own that does that, and I own a few. The rest will release if I slam the butt down, but this one does it witn minimal pressure...I could thump it with a finger and it will release.

Yeah I think folks are missing the "barely" part in the op. like the others above said, maybe the spring and bolt release need replacing. Should be a quick fix.


the spring in the bolt catch keeps it the down position, if a magazine is not inserted and the follower pushing up on the bolt catch, the only thing keeping the tension on the catch is the bolt itself. replacing the botl catch spring wont fix that.

either keep an empty mag in it, or hold the bolt release until the rifle is settled
Link Posted: 12/29/2012 6:08:39 PM EDT
Originally Posted By DamascusKnifemaker:
Originally Posted By Aiden:
Originally Posted By DamascusKnifemaker:
Happens on every AR I own. It is normal.


It's the only one I own that does that, and I own a few. The rest will release if I slam the butt down, but this one does it witn minimal pressure...I could thump it with a finger and it will release.


The brand new Colt M4 select fire I was issued as a duty weapon did this also. You can change the bolt release and put in a heavier spring (provided you can find one that fits in the hole) and it should help.


Wouldn't a heavier bolt catch spring make it worse?
Link Posted: 12/29/2012 6:09:40 PM EDT
^^ yes!
Link Posted: 12/29/2012 6:10:35 PM EDT
Originally Posted By Ventilator:
Originally Posted By DamascusKnifemaker:
Originally Posted By Aiden:
Originally Posted By DamascusKnifemaker:
Happens on every AR I own. It is normal.


It's the only one I own that does that, and I own a few. The rest will release if I slam the butt down, but this one does it witn minimal pressure...I could thump it with a finger and it will release.


The brand new Colt M4 select fire I was issued as a duty weapon did this also. You can change the bolt release and put in a heavier spring (provided you can find one that fits in the hole) and it should help.


Wouldn't a heavier bolt catch spring make it worse?


Yes it would
Link Posted: 12/29/2012 6:12:32 PM EDT
Yes, a heavier bolt catch spring will help. Also, smoothing out the faces of the bolt stop where it slides on the lower will greatly help. Use a diamond file to just knock the big peaks off the faces, the forward face is most critical.

A dab of moly grease in the lower receiver's cut where the catch rides will also help without having to remove that roll pin. And possibly damaging the lower.
Link Posted: 12/29/2012 6:14:52 PM EDT
[Last Edit: 12/29/2012 6:15:08 PM EDT by Ventilator]
Originally Posted By Keith_J:
Yes, a heavier bolt catch spring will help. Also, smoothing out the faces of the bolt stop where it slides on the lower will greatly help. Use a diamond file to just knock the big peaks off the faces, the forward face is most critical.

A dab of moly grease in the lower receiver's cut where the catch rides will also help without having to remove that roll pin. And possibly damaging the lower.


Ummmmmm.....wouldn't a heavier bolt catch spring make it worse?
Link Posted: 12/29/2012 6:16:02 PM EDT
Originally Posted By Keith_J:
Yes, a heavier bolt catch spring will help. Also, smoothing out the faces of the bolt stop where it slides on the lower will greatly help. Use a diamond file to just knock the big peaks off the faces, the forward face is most critical.

A dab of moly grease in the lower receiver's cut where the catch rides will also help without having to remove that roll pin. And possibly damaging the lower.


explain how
Link Posted: 12/29/2012 6:24:59 PM EDT
[Last Edit: 12/29/2012 6:26:02 PM EDT by a308garand]
Just put in a range safety flag, its bright yellow in color and blocks the chamber. Your range folks will see it sticking out of the ejection port from a distance and not even bother checking if the bolt is locked back or not.

or

Fit a new bolt catch and spring.

or

Send it back to Colt for repair.
Link Posted: 12/29/2012 6:32:37 PM EDT
Originally Posted By a308garand:
Just put in a range safety flag, its bright yellow in color and blocks the chamber. Your range folks will see it sticking out of the ejection port from a distance and not even bother checking if the bolt is locked back or not.

or

Fit a new bolt catch and spring.

or

Send it back to Colt for repair.


Chamber flag is the easiest fix I guess, I have a few so no cost. I just found it odd, out of several AR's some different brands...that only this one was so sensitive.
Link Posted: 12/29/2012 6:43:01 PM EDT
Originally Posted By Aiden:
Originally Posted By Rotors-R-Cool:
Originally Posted By Aiden:
Originally Posted By CCW:
Originally Posted By HKgnnr:

Bolt release and spring


This. And make sure you have not beat the shit out of the bolt release dryfiring the lower.



Don't dryfire without caps.


I think he meant dropping the hammer with the upper off the lower. The hammer will hit the bolt catch.


I did that about 1000 times to break in the trigger, but had my thumb or some wood in there to keep from impact.


Why not just dry fire it with the upper on?

Link Posted: 12/29/2012 6:46:20 PM EDT
Originally Posted By Winn:
Originally Posted By Aiden:
Originally Posted By Rotors-R-Cool:
Originally Posted By Aiden:
Originally Posted By CCW:
Originally Posted By HKgnnr:

Bolt release and spring


This. And make sure you have not beat the shit out of the bolt release dryfiring the lower.



Don't dryfire without caps.


I think he meant dropping the hammer with the upper off the lower. The hammer will hit the bolt catch.


I did that about 1000 times to break in the trigger, but had my thumb or some wood in there to keep from impact.


Why not just dry fire it with the upper on?



Easier to do while watching TV with the GF without the upper.
Link Posted: 12/29/2012 6:46:40 PM EDT
Bolt bounces and lets the bolt release go back into normal position which will let the bolt go home.
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