LR-308 issues

[hundy]

I have a JT lower I built. I have a JT upper, Arsenal Ordinance barrel (308win 1:10) and BCG. The issues I am having is that each round does eject, but it does not chamber another round. Bolt goes forward without grabbing a round. I can manually load next round, but they wont load automatically.

I am using magpul magazines, I oiled the hell out all internal parts. I did check the gas tube and block and they are all good and tight. I tried firing IMI 7.62X51 NATO and I tried American Eagle Federal 150gr 308win.

So if anyone has any suggestions I would be very happy to listen. As of now I am considering buying a different buffer tube, spring, and buffer. If that don't work a new and different BCG. I hope there is a simpler fix.

Thank you
Jay

[Junkie]

Did you make sure the gas block is positioned right? Usually there needs to be a gap between the shoulder and the block.

[Redeyedrider]

I have a JT lower I built. I have a JT upper, Arsenal Ordinance barrel (308win 1:10) and BCG. The issues I am having is that each round does eject, but it does not chamber another round. Bolt goes forward without grabbing a round. I can manually load next round, but they wont load automatically.

I am using magpul magazines, I oiled the hell out all internal parts. I did check the gas tube and block and they are all good and tight. I tried firing IMI 7.62X51 NATO and I tried American Eagle Federal 150gr 308win.

So if anyone has any suggestions I would be very happy to listen. As of now I am considering buying a different buffer tube, spring, and buffer. If that don't work a new and different BCG. I hope there is a simpler fix.

Thank you
Jay

It's short stroking. I had this happen on my .308. My cause was a loose castellated nut that was causing just enough play during the cycling of the action to create just enough friction to prevent a full stroke.

This was an easy fix so check this first.

Keep in mind that the AR manual mistakenly states to tighten to "inch pounds" (very loose). It is really supposed to be tightened to "foot pounds" (very tight).

edit to add -

I tightened it down correctly, staked it so that it doesn't work loose again, problem gone.

[CoopsDad]

The rec to check alignment of the gas block is first; second is to make sure you don't have an adjustable gas block and it's throttled down. If your gas block has an allen bolt on the side (not the bottom where it's clamped on), loosen it until it's almost all the way out then try it.

[chills]

It does sound like it's short-stroking BUT double check you have the correct Buffer/Spring/Buffer tube for the 308 application. I thought I knew what I was doing but I made a 'donkeys wobbler' of Buffer/Spring/Buffer combination in my Aero M5. I just bring it up because I think it's easily missed - springs might look the same, buffers could kinda look the same etc. Make sure you don't have BCG over travel - check the lip of the buffer tube and threads on the lower for dings.

I ended up using a RE-A5 vltor tube (had a spare), and the vltor buffer/spring combo from heavybuffersdotcom AND an adjustable gas block.

Just trying to help and cover all bases - I've been there and feel ya bro'....

[Redeyedrider]

Any luck on the diagnosis, Hundy?

[Whiskey_Tango]

Are you using 10 round or 10/20 round pmags? I never had any luck with the 10/20 pmags.

[kalieracer]

What receiver extension and buffer / spring are you using?

I have a JT lower I built. I have a JT upper, Arsenal Ordinance barrel (308win 1:10) and BCG. The issues I am having is that each round does eject, but it does not chamber another round. Bolt goes forward without grabbing a round. I can manually load next round, but they wont load automatically.

I am using magpul magazines, I oiled the hell out all internal parts. I did check the gas tube and block and they are all good and tight. I tried firing IMI 7.62X51 NATO and I tried American Eagle Federal 150gr 308win.

So if anyone has any suggestions I would be very happy to listen. As of now I am considering buying a different buffer tube, spring, and buffer. If that don't work a new and different BCG. I hope there is a simpler fix.

Thank you
Jay

[someoneeasy]

Does sound like it's short stroking. Load one in the mag to see if it locks back on an empty msgazine.

[Redeyedrider]

Let us know when you get it figured out.

[hundy]

Any luck on the diagnosis, Hundy?

No not yet, I had taken to the range twice prior to this post. I am home today (in the middle of a remodel) after moving furniture and putting up two ceiling fans, I am going to go over the rifle again.

Are you using 10 round or 10/20 round pmags? I never had any luck with the 10/20 pmags.

Straight 10 round Pmags, I even filed the front lip a little on one just to see if that made a difference and it did not.

What receiver extension and buffer / spring are you using?

I got from a friend, who picked up for me at Arsenal Ordinance in Temecula, so I am not sure if its Arsenal Ordinance or JT. I will find out today.

Did you make sure the gas block is positioned right? Usually there needs to be a gap between the shoulder and the block.

I did, but after firing again and reading your info, I am going to check again. I will check for the gap, and make sure all connections are secure and tight.

Does sound like it's short stroking. Load one in the mag to see if it locks back on an empty msgazine.

I did this on the second trip to range, and the bolt will only catch if I pull handle manually, if I shoot one single round it fires and goes forward and will not lock back, only locks back if I pull manually. If empty mag is in and I pull back it will lock in place, but not after firing single round.

I have to work Sun - Wednesday, so I probably will not be able to take back to range until Thursday (I hope) when ever I can get back to range I will post here on update.

Thank you all for help and support
Jay

[kalieracer]

Do yourself a favor and get an Armalite extension, buffer and spring. Lots of people mis match the buffer / tube and spring and mix in various parts and get odd issues.

No not yet, I had taken to the range twice prior to this post. I am home today (in the middle of a remodel) after moving furniture and putting up two ceiling fans, I am going to go over the rifle again.



Straight 10 round Pmags, I even filed the front lip a little on one just to see if that made a difference and it did not.



I got from a friend, who picked up for me at Arsenal Ordinance in Temecula, so I am not sure if its Arsenal Ordinance or JT. I will find out today.



I did, but after firing again and reading your info, I am going to check again. I will check for the gap, and make sure all connections are secure and tight.



I did this on the second trip to range, and the bolt will only catch if I pull handle manually, if I shoot one single round it fires and goes forward and will not lock back, only locks back if I pull manually. If empty mag is in and I pull back it will lock in place, but not after firing single round.

I have to work Sun - Wednesday, so I probably will not be able to take back to range until Thursday (I hope) when ever I can get back to range I will post here on update.

Thank you all for help and support
Jay

[HardwoodRods]

Hundy, load one round in the mag and fire the rifle. Does the BCG lock back? If not the issue is either gas or buffer/spring. With an empty mag pull the charging handle back. Does the BCG lock in the proper place? Need some more info

[Redeyedrider]

Hundy, load one round in the mag and fire the rifle. Does the BCG lock back? If not the issue is either gas or buffer/spring. With an empty mag pull the charging handle back. Does the BCG lock in the proper place? Need some more info

He said it does not lock back.

Sounds like you're undergassed or have a buffer/spring issue. If you don't have an adjustable gas block, then the only adjustments that you can make are buffer parts.

When my castle nut was loose it was sporadic. Sometimes it would lock back. Sometimes it would short stroke, ect....

Your issue seems like it's more defined and regular, so it will likely be a parts and/or adjustment change.

[hundy]

Do yourself a favor and get an Armalite extension, buffer and spring. Lots of people mis match the buffer / tube and spring and mix in various parts and get odd issues.

Thank you I will look into that, and see if I can find one to order.

Hundy, load one round in the mag and fire the rifle. Does the BCG lock back? If not the issue is either gas or buffer/spring. With an empty mag pull the charging handle back. Does the BCG lock in the proper place? Need some more info

After firing single round from the pmag the bullet will eject, but the bolt will go forward and not lock back. After that if I pull the charging handle with the empty mag in, then it will lock back.

He said it does not lock back.

Sounds like you're undergassed or have a buffer/spring issue. If you don't have an adjustable gas block, then the only adjustments that you can make are buffer parts.

When my castle nut was loose it was sporadic. Sometimes it would lock back. Sometimes it would short stroke, ect....

Your issue seems like it's more defined and regular, so it will likely be a parts and/or adjustment change.

I don't have a adjustable gas block, I did check it after the first range day. I even plugged up the chamber and blew air into the muzzle end, the air came out of the end of the gas tube. Did not notice any leaks at the gas block. I am going to check again when I can. I do plan on checking tube, and tightening the castle nut. If that does not work, I was thinking of ordering a new JT complete Tube/buffer/spring kit or the Armalite extension mentioned above. I may actually just order the Armalite extension today, if I can find online and not to expensive.

My goal is to try and re-fire on Thursday, If I am able to go to range I will update here.

Thank you to all again

Jay