New here, need help on first AR10

[creepin722]

Im new to the AR platform. I bought a complete AR10 upper from a gun show. All I know is it’s a 308 win. With a 1:10 twist, it came with a BCG and CH. For my lower I bought a palmetto state pa10 308 complete moe ept lower. 
When I charge the bolt it’s a little rough like it’s catching. Then when I fired a round the BCG stuck back into the buffer tube. I can dislodge it by bumping the butt on something or sometimes I have to separate the lower from the upper. 

[creepin722]

Update: both upper and lower have the curvature of an lr308.

[Armed Eye Doc]

There is a lot more information that will be needed to help you with this as there are many different possible causes.  Please read this thread and provide as much of the information as possible.

 

[jim3326]

Look up the "Waterboarding" thread to see what information is required from you to solve the issue. First guess is you have a carbine buffer and a rifle buffer tube. Bad mix

[creepin722]

1. Recoil system- DPMS LR308? (Spring and buffer)
2. Buffer weight- 4oz
3. Buffer length- 2.5”
4. Extension buffer tube internal depth- 7”
5. Spring- idk the brand, 11 3/8” long, 28 coils, has some yellow on the end of the spring
6. Gas system length- see attached picture
7. Gas tube length- 10 7/8
8. Magwell- see attached picture
9. Bolt face- attached picture
10. BCG clearance- attached picture
11. Gas journal diameter- 5/64” / Barrel diameter at gas journal- 3/4”
12. I do not have a picture of when it happened. When I fired a round the BCG stuck back in the buffer tube after ejecting the shell. 

[shooterrex]

Your buffer is to light.

This buffer along w/a springco orange spring should fix the recoil system.

https://www.kakindustry.com/lr308-carbine-buffer-heavy

You do not have enough mass in the buffer to slow down the bolt carrier group.

Your gas tube doesn't come to the middle of your cam cutout.

[creepin722]

So the buffer being too light is causing the BCG to shove back too fast and causing it to stick in the buffer tube? (I’m newer to the AR community)

[Armed Eye Doc]

I had an AR that did that.  It turned out I warped the tube when I tightened it.  An incorrect spring may also be binding up with the buffer upon recoil which could cause it to stick.  That said, Rex is correct that your buffer is too light.  

[98Z5V]

9 hours ago, creepin722 said:

For my lower I bought a palmetto state pa10 308 complete moe ept lower. 

Those are known to be proprietary (and PSA states that).  Getting them to work with other uppers is hit or miss.  That might be an issue later, after everything else here is sorted out.

9 hours ago, creepin722 said:

Then when I fired a round the BCG stuck back into the buffer tube. I can dislodge it by bumping the butt on something or sometimes I have to separate the lower from the upper. 

Did you hae a single round in the magazine at the time of firing?  If so - your gun is doing what it's supposed to do.  Locking back on the last (only) round in the mag.

You provided some decent details, but there's alot going on here.

Read this, so you can understand why the recoil system and gas system need to be balanced, for an operational, reliable gas gun:

 

Edited April 3, 2023 by 98Z5V

[98Z5V]

7 hours ago, creepin722 said:

Update: both upper and lower have the curvature of an lr308.

Also, just based on these pics, and the orientation of the spring and the buffer in the pics...  How are you putting the spring and buffer into the extension?  I hope it's not like it's shown in the pics.  Not trying to insult - asking based on what I'm seeing here.

[creepin722]

What are you referring to when you say putting them into the extension? It was my understanding that the spring slides onto the buffer and slides into the buffer tube? No insult taken, I’m just trying to learn and fix the issue. Thanks 

[creepin722]

Also, the magazine had 4 rounds in it and it stuck back with 3 still in the mag.

[Armed Eye Doc]

4 minutes ago, creepin722 said:

What are you referring to when you say putting them into the extension? It was my understanding that the spring slides onto the buffer and slides into the buffer tube? No insult taken, I’m just trying to learn and fix the issue. Thanks 

He means that the buffer face should be facing out to contact the bcg, like this.

[creepin722]

Ok, yeah so like this (picture). This is how I put back in and how it originally was. I’m still reading through the forums posted above. There a lot of info

[Armed Eye Doc]

3 minutes ago, creepin722 said:

Ok, yeah so like this (picture). This is how I put back in and how it originally was. I’m still reading through the forums posted above. There a lot of info

That's great.   The buffer and spring were laid down backwards in the picture.

[98Z5V]

4 minutes ago, Armed Eye Doc said:

That's great.   The buffer and spring were laid down backwards in the picture.

Exactly.  And why I asked in the first place.  From the pic, if taken out of the rifle - looks like the buffer went in there first, and the spring was touching the base of the BCG.

I didn't take the pics - and nobody has ever taken pics like that before and posted them here - like that.  There's a reason to ask, when seeing that. 

[98Z5V]

16 minutes ago, creepin722 said:

Ok, yeah so like this (picture). This is how I put back in and how it originally was. I’m still reading through the forums posted above. There a lot of info

It wouldn't even shock me in the least if someone that works at PSA installed it buffer first, and spring against the back of the BCG.  Wouldn't even suprise me to hear something like that.  You bought a PSA complete lower - and I had to ask.  TSA Bag Smashers and Ramp Monkeys are better than the "gun builders" at PSA.

[creepin722]

This is my first AR10 so I just bought a budget(ish) upper and lower to mess with and learn. I’ve ordered the orange spring and after reading on the springco site it makes sense to have it. Im also about to order the 5.3 oz buffer. Not sure how to make the gas tube line up with the center of the cam cut out

[98Z5V]

26 minutes ago, creepin722 said:

Not sure how to make the gas tube line up with the center of the cam cut out

You have to buy a new gas tube that's the proper length for your gas system, and your gas port drilling position - by whomever made that barrel.  That's the only way to fix that one.

[98Z5V]

4 hours ago, creepin722 said:

• Gas system length- see attached picture
• Gas tube length- 10 7/8

You never did state how long the barrel is.  You didn't state what gas system you have - just "see attached pic" that doesn't tell us.  Especially when you state the gas tube length - that's not even a length for a common gas tube, unless that's some custom barrel.

No gas block journal diameter, no gas port diameter.  There's a ton of things going wrong with this gun, but we'll never be able to guess our way through it without accurate information from you...

If you want to make this gun run, reliably - then we'll need ALL the information from the Waterboarding thread that was posted.  Answers of "see attached pic" don't work.  Numbers, though...  Numbers work...  Numbers from YOU, not some BS that a manufacturer thinks it should be, on any given Sunday... 

You need to take this thing apart, and measure what's needed to be measured, provide results, and we can fix this gun and make it run.

That's really the only way to do it over the internet, looking at pics and written words from someone.  Details, are the only thing that makes it run. 

Edited April 3, 2023 by 98Z5V

[creepin722]

I will try my best to get accurate measurements tomorrow. Just trying to figure out what I’m measuring and how to take it apart without destroying parts. Seems simple but I’ve never broke down a gun this far.

[98Z5V]

50 minutes ago, creepin722 said:

I will try my best to get accurate measurements tomorrow. Just trying to figure out what I’m measuring and how to take it apart without destroying parts. Seems simple but I’ve never broke down a gun this far.

There are videos on the internet on how to take a gas block off.  That's really the majority of the work that needs to be done.  That's how you get to the gas port, and measure it's diameter. And the gas bloc journal size.  Once the block is loose from the barrel, you can measure the gas tube length. 

We can figure out what your gas tube length needs to be, with that good pic up into the upper, showing the protrusion into the upper.  Perfect looks like this:

If you pay attention to the Waterboarding thread that was already link in here, it specifies what details are needed, and it includes pics, of said details.

The other thread I linked in here on gas ports, buffers, etc - that's the WHY on all this stuff is important.

You've been given the information.  Spoonfeeding to extract information will get very old, very quick.  All the info is there for you.  You just need to do it, and provide that pertinent info back.  Otherwise, we can guess all day.  We'll come up with something - might work, might not.

[creepin722]

The gas port is 5/64” and the barrel measurement at the gas port is 3/4” (#11)

I measured what the picture shown in the waterboarding thread. But to measure the tube, am I taking the tube out of the gas block? Or like this (pic) it reads 11 7/8” although it looks like 12 in the picture.

[creepin722]

[creepin722]

Here is a couple pictures of the malfunction. It sometimes sticks back like this when I pull the CH. when fired it sticks back every time. Am I correct to assume that the buffer and spring are just not strong enough to shove it back?

*I have ordered the buffer and spring recommend above.