AR-15 problem?

lawndoctor1 · November 21, 2016, 07:23 PM

I took my new AR-15 to the range today so I could shoot it for the very first time. My rifle is chambered in 7.62x39...by the way.

After firing the last round in the 20rd mag, my bolt wouldn't lock back. I can insert this one magazine completely empty and pull back the charging handle,and everything locks back like it should.

Is this prob a magazine problem or something else as to why it won't lock back after firing the last round?

Nathan · November 21, 2016, 07:42 PM

It is possibly a short stroking issue or weak mag spring. Do other mags work?

lawndoctor1 · November 21, 2016, 07:49 PM

I haven't tried another mag yet. I was going to try that first...before looking deeper.

HiBC · November 24, 2016, 06:18 AM

The word "New" may imply it has not been cleaned of preservative(not particularly a lube) and then lubricated.
A new gun tends to have a bit more friction in the works.
A lack of lubrication aggravates the problem
A new recoil spring may be a bit on the stiff side for a few hundred rounds.
Bargain ammo or conservative reloads may lack a bit of "umph"

Clean it,lube it,shoot it a while.I suggest you count your rounds down and avoid having the bolt stop over ridden for a reasonable break in period.
You may find its all healed up.
If the problem persists.tell us.We'll try plan "B"

lawndoctor1 · December 10, 2016, 03:15 PM

I took my rifle to the range again today. I used a brand new/different mag. A 10 Round 7.62x39 Stainless Steel C Products Defense mag. The slide would still not stay open on the last round. Any advice,thoughts,etc????

HiBC · December 10, 2016, 04:58 PM

I have a number of "C" Products mags.They work very well for me.I'd say you eliminated the magazine as a problem,most likely.

Either the bolt stop functions smoothly/reliably,or it does not.Thats the dookickey on the left side of the receiver.

OK,I reread your post.You have sufficient travel via the Op rod.The catch functions if the bolt carrier travels far enough.

You need at least one of the following:

1) More gas: Ammo? Ports? (gas block alignment)Gas rings?(Gaps offset) ???
2) Lighter buffer H-3,H-2,H-1,H....they are one place you can tune the cycle
3) Less friction Wear in" Lubrication?
4) Less spring. Wear in spring? Buy lighter Spring?

It will run.

There are lot of "AR-15"'s out there,from "bargain" to Cadillac,just like there are a lot of 1911's.

The 7.62x39 is a variable.Its an adaptation.You may have a bug to work out.

Like a new computer or Windows 10. Breathe deep.

November 21, 2016, 07:23 PM	#1
lawndoctor1 Member Join Date: October 29, 2016 Posts: 76	AR-15 problem? I took my new AR-15 to the range today so I could shoot it for the very first time. My rifle is chambered in 7.62x39...by the way. After firing the last round in the 20rd mag, my bolt wouldn't lock back. I can insert this one magazine completely empty and pull back the charging handle,and everything locks back like it should. Is this prob a magazine problem or something else as to why it won't lock back after firing the last round?

December 10, 2016, 04:58 PM	#6
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,289	I have a number of "C" Products mags.They work very well for me.I'd say you eliminated the magazine as a problem,most likely. Either the bolt stop functions smoothly/reliably,or it does not.Thats the dookickey on the left side of the receiver. OK,I reread your post.You have sufficient travel via the Op rod.The catch functions if the bolt carrier travels far enough. You need at least one of the following: 1) More gas: Ammo? Ports? (gas block alignment)Gas rings?(Gaps offset) ??? 2) Lighter buffer H-3,H-2,H-1,H....they are one place you can tune the cycle 3) Less friction Wear in" Lubrication? 4) Less spring. Wear in spring? Buy lighter Spring? It will run. There are lot of "AR-15"'s out there,from "bargain" to Cadillac,just like there are a lot of 1911's. The 7.62x39 is a variable.Its an adaptation.You may have a bug to work out. Like a new computer or Windows 10. Breathe deep. Last edited by HiBC; December 10, 2016 at 05:20 PM.

November 21, 2016, 07:42 PM	#2
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,336	It is possibly a short stroking issue or weak mag spring. Do other mags work?

November 21, 2016, 07:49 PM	#3
lawndoctor1 Member Join Date: October 29, 2016 Posts: 76	I haven't tried another mag yet. I was going to try that first...before looking deeper.

November 24, 2016, 06:18 AM	#4
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,289	The word "New" may imply it has not been cleaned of preservative(not particularly a lube) and then lubricated. A new gun tends to have a bit more friction in the works. A lack of lubrication aggravates the problem A new recoil spring may be a bit on the stiff side for a few hundred rounds. Bargain ammo or conservative reloads may lack a bit of "umph" Clean it,lube it,shoot it a while.I suggest you count your rounds down and avoid having the bolt stop over ridden for a reasonable break in period. You may find its all healed up. If the problem persists.tell us.We'll try plan "B"

December 10, 2016, 03:15 PM	#5
lawndoctor1 Member Join Date: October 29, 2016 Posts: 76	I took my rifle to the range again today. I used a brand new/different mag. A 10 Round 7.62x39 Stainless Steel C Products Defense mag. The slide would still not stay open on the last round. Any advice,thoughts,etc????