Addressing PA-10 issues

[Bluedog225]

 

I was hoping for some help with my Palmetto AR-10.  I have reviewed many of the existing threads and worked up a plan and a few questions.  It was a poorly researched purchase in 2017.  I realize the product has some issues.  This is a learning platform for me and I don’t mind spending some extra time learning my way around.  

 

I’d like a reliable and predictable gas system.  Although it seems to be working fine as is.  Only about 50 rounds through it.  Federal xm80c, 149 grain.  One failure to eject and that was with the magazine out.

 

It looks like this particular product has the following issues:

 

-The gas port diameter is less than 3/32” (0.09375”)  Waiting on new drill bits to check get and exact number.  

-The buffer is light (3.77 ounce buffer-PA-10/ 2.500 inch buffer length).

-I believe the spring is light (11 inch with 25 coils not counting first and last).

-The gas tube ends in the front 1/3 of the cam pin cutout.

 

I’d like to:

-replace the gas tube  (Armalite 15.5”)

-appropriately size the gas port (3/32)

-get the right buffer -KAK 5.3 ounce carbine buffer (is carbine right?)

-get the right spring (Sprinco Orange spring  for .308 for 7.000” internal depth carbine receiver extension and 2.500” long buffer).  

 

But I don’t want to mess up the timing.  Maybe these irregular items are designed to work together?

 

In reading about things like dwell time, gas port diameters, and balancing the recoil system, I’m a little hesitant to start down this road.  Doing any work with a .001 tolerance is way above my pay grade.

 

Any thoughts appreciated.

 

Thanks

Tom

 

 

“As-is” specs:

PA-10 Gen 2

18 inch midlength stainless

7 inch buffer tube

11 inch spring with 25 coils not counting first and last

3.77 ounce buffer (PA-10)/ 2.5 inch buffer length

Short gas tube (1/3 through cam pin cutout)

Small gas port (less than 3/32”)

MPI bolt (not sure if standard or upgraded)

Feed ramps look pretty good/polished.

 

 

 

[Armed Eye Doc]

Welcome to the forum and thank you for doing your research first. . You definitely need a heavier buffer.  The one you listed is the preferred replacement if you stay with the 7 inch receiver extension.  An alternative is the complete Armalite kit.  https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01

It appears to be in stock at the moment but it is not always.  It will certainly work well with your PA-10.  You may need a little more gas after getting a heavier buffer, but I would only change one thing at a time.

[shooterrex]

On my PA10 w/the 18" barrel I used this gas tube not the rifle length.

https://www.armalite.com/SACItem.aspx?Item=10007005

[Bluedog225]

Yes, I got the gas tube length wrong.  Don’t think I can edit the original.  Thanks all.

[98Z5V]

4 hours ago, Bluedog225 said:

 

But I don’t want to mess up the timing.  Maybe these irregular items are designed to work together?

 

That gun came "timed from the factory" to run on junk ammo for most people, and work most of the time. Far from perfect, and FAR from reliable.  It was built CHEAP, with the least money spent, and that's why it has a 3.8oz buffer - because heavier 2.500" buffers cost alot more to get them close to the 5.4oz standard.  That involves tungsten and stainless, instead of steel and aluminum.  PSA isn't spending that kind of money, not on a buffer.  Even if they did - their "builders" would get it wrong most of the time.

Your research just told you what you need to do to make it a reliable gun, with any ammo that you throw at it.  The 18" midlength barrel - provided it has a 0.750" gas block journal - needs 0.080"~0.085" gas port diameter, to run RIGHT.    Don't know where you got that 0.093" from.

Do the rest of the mods that you're already thinking about, and posted.  You didn't "fall into this information" by accident.  There's a reason we've been posting this info for years here, now.

[DNP]

He mentioned in another thread the 3/32 wouldn’t fit. I guessed that it was going to be a small hole and mentioned you guys might call for an upsizing. I couldn’t remember the numbers you have locked down, but figured one of you gurus would chime in with that. 

[Bluedog225]

Thanks for the info.  I incorrectly got the 0.093 from a post about a 20” barrel with a 0.750 gas block journal.

[Cliff R]

There are too many "gaps" in fractional drill bit sizes.  I recommend getting a #1-60 drill bit set for this sort of work.  Also a good idea to get USA made bits vs the Chinese variety.  They tend to break if you stare at them too long!

 

Huot or Norseman would be my first choice and good idea to pick up a few pin vises to hold the smaller ones.......FWIW......Cliff

 

 

[Bluedog225]

Good info on brands and sizing.  Thanks.

With regards to the new buffer tube and buffer, is there a preference between the DPMS standard AR15 buffer tube with a shortened buffer versus armalite with a standard buffer and longer tube?  Assuming they are the proper weight?

[Bluedog225]

Wish I could find a way to edit these.  Found this thread and think it answers my questions.  

 

[98Z5V]

20 hours ago, Bluedog225 said:

Thanks for the info.  I incorrectly got the 0.093 from a post about a 20” barrel with a 0.750 gas block journal.

That was probably a rifle gas length system on that barrel, too, that you got that information from.  Definitely the port size for a rifle-gas 20".  Not a midlength gas system 18" barrel, like you have. 

These little details make a HUGE difference. So many people just blow that off, so commonly.  Just think it's nothing.

It means everything.  Details really do matter, and ALL the details, too. Not just some of them. Your gun either runs, or it doesn't. We help you make it run - or we fail.  Details...

Garbage in, garbage out, just like the smartest computer.  We're not that "smartest computer" - we need your real no-shiit gun details and measurements, here.  If we don't get those real no-shiit numbers that we ask for...  then we're no better than "garbage in-garbage out"...

 

I hope everyone understands that aspect of it.

[edgecrusher]

1 minute ago, 98Z5V said:

That was probably a rifle gas length system on that barrel, too, that you got that information from.  Definitely the port size for a rifle-gas 20".  Not a midlength gas system 18" barrel, like you have. 

These little details make a HUGE difference. So many people just blow that off, so commonly.  Just think it's nothing.

It means everything.  Details really do matter, and ALL the details, too. Not just some of them. Your gun either runs, or it doesn't. We help you make it run - or we fail.  Details...

Garbage in, garbage out, just like the smartest computer.  We're not that "smartest computer" - we need your real no-shiit gun details and measurements, here.  If we don't get those real no-shiit numbers that we ask for...  then we're no better than "garbage in-garbage out"...

 

I hope everyone understands that aspect of it.

Go to bed lol

[98Z5V]

2 minutes ago, edgecrusher said:

Go to bed lol

Sleep is for the weak.  I rest, momentarily throughout the day - for a few seconds at a time - so I can monitor everything around me 24/7.

You can sleep when you're dead, brother. 

[edgecrusher]

1 minute ago, 98Z5V said:

Sleep is for the weak.  I rest, momentarily throughout the day - for a few seconds at a time - so I can monitor everything around me 24/7.

You can sleep when you're dead, brother. 

That’s pretty much my mantra. If I can gather 3-5 hours there’s enough hate left to fuel me the rest of the way

[98Z5V]

7 minutes ago, edgecrusher said:

That’s pretty much my mantra. If I can gather 3-5 hours there’s enough hate left to fuel me the rest of the way

I love this quote from you.  It just echoes me, entirely.

 

Edited October 8, 2020 by 98Z5V

[Cliff R]

2 hours ago, edgecrusher said:

If I can gather 3-5 hours there’s enough hate left to fuel me the rest of the way

+2

There are just WAY too many things to do each day and not nearly enough hours to get to all of them......

[Bluedog225]

Good morning,

Making some progress.  I’ve got some a buffer, spring, and Norseman bits on the way.

I’ve looked around for the recommended Armalite carbine gas tube but it is not in stock.  It’s on the Armalite site but will not go into cart.

Any suggestions for an alternative appreciated.  I’ve seen suggestions to bend/cut a longer tube but I’m hesitant to go down that road without checking.

Thanks

[Bluedog225]

I wish I could edit these posts.  Armalite calls it “carbine length.”  It’s 12 1/16”

[DNP]

I think some of your editing abilities will show up in a while, but the edit feature had to be modified to preserve some comments for life. Like everything in life, a few bad actors ruined it for everyone. 

[edgecrusher]

10 hours ago, Bluedog225 said:

I wish I could edit these posts.  Armalite calls it “carbine length.”  It’s 12 1/16”

That’s correct. Give them a call, they are usually very accommodating 

[Rsquared]

17 hours ago, 98Z5V said:

Sleep is for the weak.  I rest, momentarily throughout the day - for a few seconds at a time - so I can monitor everything around me 24/7.

You can sleep when you're dead, brother. 

Yes

17 hours ago, edgecrusher said:

That’s pretty much my mantra. If I can gather 3-5 hours there’s enough hate left to fuel me the rest of the way

And Yes.

[98Z5V]

13 hours ago, Bluedog225 said:

I wish I could edit these posts.  Armalite calls it “carbine length.”  It’s 12 1/16”

That's what you need, man. 

3 hours ago, edgecrusher said:

That’s correct. Give them a call, they are usually very accommodating 

He's correct ^^^   - Calling them on the phone is quite successful, most of the time. 

[Bluedog225]

Good morning,

My current gas port is 0.076 (as measured with the #48 Norseman drill bit).

My next choices are 0.078” (#47) or 0.081” (#46).  It looks like the 0.081 is the right bit to hit 0.080”-0.085”.

Can I clamp the barrel on the (cheap) drill press and simply drill out the larger hole?  Or is this the type of operation that needs better equipment or a gunsmith?  I can get pretty good alignment with the #47 and then switch bits.  

Any thoughts appreciated.

 

[shooterrex]

Put a pencil or wooden dowel rod in the bore. Go slow and use oil. Just take your time.

[DNP]

What he said^^^^
 

wooden dowel gives you something to bounce off of when you push through and protects the other side of the barrel. A lot of guys on here have drilled this on their own and been happy with the results. Don’t forget to clean the barrel up well when you’re done.