AR spring malfunction - The Firearms Forum

ckill1 · 12-27-2010, 02:00 PM

OK all you AR gurus out there...I have a question for you. I returned my Trijicon reflex to my AR after finishing up deer season(I use the reflex on my slug gun also) & went out to sight it back in. Just about had it dialed in when the weapon failed. I had loaded 20rds in a Pmag & was about 4 shots into the string when it happened. There was a round in chamber, didnt know whether live or not, & trigger was locked up. Tried to clear by retracting the bolt, but would only come back about 3/4inch. I ended up having to pull both reciever pins to clear the round. It was fired, so malfunction occured after shot but before ejection. When I pulled the upper away from the lower a mangled spring fell out. I can't tell you where it came from or what it originally looked like. Even after the lower was removed, the trigger is still locked up.
I assembled this from a stripped DPMS lower, a RRA lower parts kit, and a Tactical Machining upper about 18mos ago. I know I should remember all the springs & such but its been a rediculously reliable weapon since assembly. I havent thought much about it. I will tear into it myself, but thought Id ask here in case someone had a place in which to start or an idea as to which spring failed & maybe why.
Thanks for the help,

Chris

ckill1 · 12-27-2010, 02:04 PM

Oh, I forgot to add...
for Christmas I had gotten a new single point sling & mount from the girls, so I had mounted that as well. It fits around the buffer spring between the A1 buttstock & reciever & is about 1/8in thick. Could this have contributed?

jlloyd73 · 12-27-2010, 03:16 PM

Post a picture of the spring you are referring to. Most sling-mounts mount around the buffer tube and the only little spring you have had to mess with would have been the spring for the the rear take-down pin (if you had to take the buttstock off to install the sling-mount). This problem should be easy to reason out because the AR platform is pretty uncomplicated....but pictures help a lot. All the trigger parts need to be looked at.

retired grunt · 12-27-2010, 03:42 PM

Hammer spring maybe?

BillM · 12-27-2010, 04:01 PM

I get a guess!

Is it the buffer retainer spring? Thats the spring under the buffer retainer
plunger, right at the end of the buffer tube in the lower. Spacing your
buffer tube back 1/8" with the sling mount probably let that little sucker
loose--which means the plunger is rattling around in there SOMEWHERE

ckill1 · 12-27-2010, 04:37 PM

& I think we have a winner folks! When I take the upper off, the rear reciever pin comes all the way out & the buffer assembly springs forward to the trigger group(which is still locked up, by the way. Suppose the plunger is somewhere in the trigger group, jamming it up? Further investigation requuired...

tim.sr · 12-27-2010, 04:38 PM

that is my bet to

GunHugger · 12-27-2010, 06:14 PM

Since it locked after firing with the bolt forward I would first try to move the bolt carrier/bolt forward to see it you can remove what's locking up the rearward movement. I'm guessing that forcing it to the rear may really jamb it up. I would try forward first.

ckill1 · 12-28-2010, 12:25 AM

Well, I was able to pull the buffer retainer plunger out of the trigger assembly, freeing that up. The buffer retainer plunger spring is twisted all out of shape & Im missing the rear reciever pin spring as well! Oh, well, off to the gun shop in the am...

BillM · 12-28-2010, 07:18 AM

Glad it was nothing serious. The gun will run just fine with both of
those springs and the plunger missing. Kind of a pain in the butt
holding the buffer in while you swing the upper
down into place---but it can be done.

Yes--I'm speaking from experience.

ckill1 · 12-28-2010, 06:27 PM

Problem solved! New plunger spring, new reciever pin detent spring, exchanged the A2 sling mount for the proper A1 model(duh!) & she runs like a champ! Thanks for answering my simple questions!

Chris

12-27-2010, 02:00 PM	#1
ckill1 V.I.P. Member Join Date: Dec 2007 Location: SW Iowa Posts: 299	AR spring malfunction OK all you AR gurus out there...I have a question for you. I returned my Trijicon reflex to my AR after finishing up deer season(I use the reflex on my slug gun also) & went out to sight it back in. Just about had it dialed in when the weapon failed. I had loaded 20rds in a Pmag & was about 4 shots into the string when it happened. There was a round in chamber, didnt know whether live or not, & trigger was locked up. Tried to clear by retracting the bolt, but would only come back about 3/4inch. I ended up having to pull both reciever pins to clear the round. It was fired, so malfunction occured after shot but before ejection. When I pulled the upper away from the lower a mangled spring fell out. I can't tell you where it came from or what it originally looked like. Even after the lower was removed, the trigger is still locked up. I assembled this from a stripped DPMS lower, a RRA lower parts kit, and a Tactical Machining upper about 18mos ago. I know I should remember all the springs & such but its been a rediculously reliable weapon since assembly. I havent thought much about it. I will tear into it myself, but thought Id ask here in case someone had a place in which to start or an idea as to which spring failed & maybe why. Thanks for the help, Chris __________________ People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf. -->

12-27-2010, 02:04 PM	#2
ckill1 V.I.P. Member Join Date: Dec 2007 Location: SW Iowa Posts: 299	Re: AR spring malfunction Oh, I forgot to add... for Christmas I had gotten a new single point sling & mount from the girls, so I had mounted that as well. It fits around the buffer spring between the A1 buttstock & reciever & is about 1/8in thick. Could this have contributed? __________________ People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf.

12-27-2010, 03:16 PM	#3
jlloyd73 Advanced Senior Member Join Date: Nov 2010 Contributor Posts: 1,932	Re: AR spring malfunction Post a picture of the spring you are referring to. Most sling-mounts mount around the buffer tube and the only little spring you have had to mess with would have been the spring for the the rear take-down pin (if you had to take the buttstock off to install the sling-mount). This problem should be easy to reason out because the AR platform is pretty uncomplicated....but pictures help a lot. All the trigger parts need to be looked at.

12-27-2010, 03:42 PM	#4
retired grunt V.I.P. Member Join Date: Mar 2009 Location: Northern NY Posts: 416	Re: AR spring malfunction Hammer spring maybe? Attached Images

12-27-2010, 04:01 PM	#5
BillM V.I.P. Member Join Date: Jan 2010 Location: Amity Orygun Posts: 380	Re: AR spring malfunction I get a guess! Is it the buffer retainer spring? Thats the spring under the buffer retainer plunger, right at the end of the buffer tube in the lower. Spacing your buffer tube back 1/8" with the sling mount probably let that little sucker loose--which means the plunger is rattling around in there SOMEWHERE

12-27-2010, 04:37 PM	#6
ckill1 V.I.P. Member Join Date: Dec 2007 Location: SW Iowa Posts: 299	Re: AR spring malfunction & I think we have a winner folks! When I take the upper off, the rear reciever pin comes all the way out & the buffer assembly springs forward to the trigger group(which is still locked up, by the way. Suppose the plunger is somewhere in the trigger group, jamming it up? Further investigation requuired... __________________ People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf.

12-27-2010, 04:38 PM	#7
tim.sr V.I.P. Member Join Date: May 2009 Location: MI. Posts: 290	Re: AR spring malfunction that is my bet to __________________ Tim.Sr U.S.ARMY VET.

12-27-2010, 06:14 PM	#8
GunHugger Advanced Senior Member Join Date: Jul 2007 Location: SW PA Posts: 1,161	Re: AR spring malfunction Since it locked after firing with the bolt forward I would first try to move the bolt carrier/bolt forward to see it you can remove what's locking up the rearward movement. I'm guessing that forcing it to the rear may really jamb it up. I would try forward first. __________________ . “There will be a revolution in this country!” “I don’t believe people should to be able to own guns.” ~Barack Obama "Stand your ground. Don't fire unless fired upon, but if they mean to have a war let it begin here." ~Captain John Parker, to his Minute Men on Lexington Green, April 19, 1775.

12-28-2010, 12:25 AM	#9
ckill1 V.I.P. Member Join Date: Dec 2007 Location: SW Iowa Posts: 299	Re: AR spring malfunction Well, I was able to pull the buffer retainer plunger out of the trigger assembly, freeing that up. The buffer retainer plunger spring is twisted all out of shape & Im missing the rear reciever pin spring as well! Oh, well, off to the gun shop in the am... __________________ People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf.

12-28-2010, 07:18 AM	#10
BillM V.I.P. Member Join Date: Jan 2010 Location: Amity Orygun Posts: 380	Re: AR spring malfunction Glad it was nothing serious. The gun will run just fine with both of those springs and the plunger missing. Kind of a pain in the butt holding the buffer in while you swing the upper down into place---but it can be done. Yes--I'm speaking from experience.

12-28-2010, 06:27 PM	#11
ckill1 V.I.P. Member Join Date: Dec 2007 Location: SW Iowa Posts: 299	Re: AR spring malfunction Problem solved! New plunger spring, new reciever pin detent spring, exchanged the A2 sling mount for the proper A1 model(duh!) & she runs like a champ! Thanks for answering my simple questions! Chris __________________ People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf.