My PA10 project

[ApexJunky]

 Here is a little back story of the rifle before we begin the first round of “why in the fornicate”!

 I picked up this Gen 2 basket case from a buddy that had enough after only 60 rounds or so. If I recall correctly, for $400. It’s an 18” barrel model. He didn’t do much with it but he gave it a DIY low profile gas block mod. He mentioned that it would have FTF issues and the bolt wouldn’t lock back on the last round. He kept the scope but tossed a few PMAGs, some ammo and an adjustable gas block in the box. Couldn’t pass it up.

 When I got her in hands my first impression was that it was pretty much bone dry. That led me to believe it would at least cycle once I lubed her up with my favorite stuff. Also installed a Magpul PRS stock and a Nikon P308 scope. Stopped in a local sugar cane field and put 10 rounds  after work one day.

She kicks more than my M1A, that’s for sure. I decided to have the gas block installed and switched to a Midwest Industries free floated handguard to dress it up some. The bipod is a cheap UTG that splits time with my other rifles.

Between my job and Mustang hobby this guy has generally sat dormant since first quarter 2019 but I decided to start the unfucking process.

Edited February 5, 2020 by ApexJunky

[ApexJunky]

The bolt wouldn’t stay locked back. I have attributed this to worn magazine followers damaged from the bolt lugs slamming into them. You can see it progressively gets worse over time and it will not stay open on the most damaged mag. Not even if you ride the charging handle slowly until it stops.

 

Is this common? If so, what is the usual remedy?

[ApexJunky]

Did some reading on this forum over the past weekend and decided to take a proactive approach. Placed an order for the appropriate buffer spring (heavybuffers.com) and to bring the buffer weight up to H3 spec. I’m waiting for these parts to arrive until I bring her back to the range. I’m also going to notch the buffer tube to facilitate threading it flush with the lower receiver.

 

This is where I stand with it. Also... Yuck. I despise the finish on this gun. I’ll likely have it cerakoted once it runs properly.

 

 

Edited February 5, 2020 by ApexJunky

[98Z5V]

Focus hard on the internal depth of that PSA receiver extension before you stick any of those new parts in there.  Measure it. Accurately.

They shipped some of those PA-10 receiver extensions that were 8.000" internal depth, and that's a nightmare to deal with.

[ApexJunky]

13 hours ago, 98Z5V said:

Focus hard on the internal depth of that PSA receiver extension before you stick any of those new parts in there.  Measure it. Accurately.

They shipped some of those PA-10 receiver extensions that were 8.000" internal depth, and that's a nightmare to deal with.

Roger that. 

[shooterrex]

19 hours ago, ApexJunky said:

The bolt wouldn’t stay locked back. I have attributed this to worn magazine followers damaged from the bolt lugs slamming into them. You can see it progressively gets worse over time and it will not stay open on the most damaged mag. Not even if you ride the charging handle slowly until it stops.

 

Is this common? If so, what is the usual remedy?

It sure looks like the bolt is being locked open on the follower NOT the bolt catch. Does the bolt come back far enough to lock back on the bolt catch?

[ApexJunky]

On 2/5/2020 at 2:38 PM, shooterrex said:

It sure looks like the bolt is being locked open on the follower NOT the bolt catch. Does the bolt come back far enough to lock back on the bolt catch?

That’s what it seems like for sure. I’ll check that as soon as I get home.

Edited February 7, 2020 by ApexJunky

[ApexJunky]

On 2/4/2020 at 9:39 PM, 98Z5V said:

Focus hard on the internal depth of that PSA receiver extension before you stick any of those new parts in there.  Measure it. Accurately.

They shipped some of those PA-10 receiver extensions that were 8.000" internal depth, and that's a nightmare to deal with.

The depth is 7” on my receiver extension:

 

The PSA supplied buffer weighs in at 3.8 oz:

The 11.5”/28 coil spring PSA supplied buffer spring:

The 10.9375”/28 coil spring that heavybuffers.com sent me:

On 2/5/2020 at 2:38 PM, shooterrex said:

It sure looks like the bolt is being locked open on the follower NOT the bolt catch. Does the bolt come back far enough to lock back on the bolt catch?

Here is the bolt locked back with the catch:

 

Edited February 7, 2020 by ApexJunky

[98Z5V]

Receiver extension looks alright - get it in another turn, file a notch or make a cutout in the bottom, to clear the tip of the buffer retainer.  Before you file or cut, remove the buffer retainer completely, thread that extension in one more turn, and verify that you can still close your upper receiver down on the lower, and pin it there.  Do that before any cutting/filing.

That buffer and spring are junk.  Sprinco Orange spring, for the 7.000" internal setups (AR15 carbine receiver extensions).  KAK makes a 2.500" long buffer that weighs in at 5.3oz, and that's close enough to 5.4oz to call it good.  Those two parts... 

Edited February 7, 2020 by 98Z5V

[jtallen83]

Tube looks a bit short. What length is the buffer? Could be an I am seeing things but it looks like an AR-15 buffer. That bolt is not locked back, the catch should grab the bolt not the carrier.

[98Z5V]

6 15/16" internal depth is the true Armalite M15 spec for an AR15 Carbine Receiver Extension.  Most of the aftermarket and other companies just do 7.000" internal, and it works well.  Not to the Armalite spec, but it works.  That extension is good. 

Edited February 7, 2020 by 98Z5V

[shooterrex]

32 minutes ago, jtallen83 said:

That bolt is not locked back, the catch should grab the bolt not the carrier.

That is why the bolt is messing up your followers.

[98Z5V]

Guys, this is all happening because of the weak recoil system, and the "down-sized" gas port diameter, that let's the weak recoil system "run for most people with most ammo..."

That bolt is running too fast for the catch to catch it - because the recoil system is too light/weak.  The remedy at that factory is to cut the gasport down from where it should be, to 0.010"~0.015" undersized.  That's why most people think these guns are "over-gassed" an just add an adjustable gas block.  Putting the Band-Aid on the wrong cut...

It's a PSA 18" midlength gas barrel, so it's going to have a gas port diameter of 0.070" - and the OP is gonna find that out when he takes that gas block off to drill it up.  It needs to be 0.080"~0.085" for an 18" .308 Win barrel with a midlength gas system and a 0.750 gas block journal size.

Edited February 7, 2020 by 98Z5V

[ApexJunky]

I fucking love this place.

[jtallen83]

1 hour ago, 98Z5V said:

 

Guys, this is all happening because of the weak recoil system, and the "down-sized" gas port diameter, that let's the weak recoil system "run for most people with most ammo..."

 

If that is where it locks back at when hand cycling then wouldn’t that be a dimensional issue? 
 

@ApexJunky is that as far back as you can pull the bolt?

[ApexJunky]

19 minutes ago, jtallen83 said:

If that is where it locks back at when hand cycling then wouldn’t that be a dimensional issue? 
 

@ApexJunky is that as far back as you can pull the bolt?

It goes back a little more then that, I’d say about 1/4” but I’ll have to check again to be sure.

[98Z5V]

22 minutes ago, jtallen83 said:

If that is where it locks back at when hand cycling then wouldn’t that be a dimensional issue? 
 

Not with a 6 15/16" extension and a 2.500" buffer - wouldn't do that. The room is there to lock a .308 AR back with those dimensions - unless that spring hit coil-bind before that.  Wire diameter and length of spring doesn't look like something that would coil-bind, and prevent that from locking back.

This is a BCG speed issue - due to a bad selection of parts from the manufacturer.  My favorite Bad Manufacturer. These guys are my  "  @Robocop1051 Hates CMMG," for him.  These guys just can't get it right, and don't listen to the obvious. They can't make reliable guns, but claim that they are making guns for everyone, spreading freedom...  at the cheapest price point.  They need to spend money (on H3 buffers and appropriate receiver extensions) and get their gas ports in line with functional guns, in order to send out "functional guns - for most of the people, most of the time, with most of the ammo."   Instead, they cheap out.  Making a "Functional Gun" is gonna cost enough money to spend on tungsten, and make an appropriate buffer, in the first place.  If they stick to that AR15 receiver extension, it's gona cost even MORE money, on making that buffer body out of stainless steel, instead of aluminum.  That's "two counts" of "you need to spend more money..." to make a functional gun.  

This is the cheapest .308AR out there - with a "Lifetime Guarantee" - and it doesn't work.  Because...  I've stated it all before. They're not gonna spend any money on two tungsten weights for a buffer, and stainless steel for the buffer body, in order to bring that buffer weight up to 5.3 or 5.4 oz - so they can THEN have a proper gas port diameter - to make a functional gun.  Cheaper is better.  That's their goal. 

That's why most people that don't know what they're doing here, think that they need an adjustable gas block to "tame down" an over-gassed gun - that has a gas port diameter that 0.010"~0.015" undersized...   So, with a too-small gas port...  How the fuk is that thing "over-gassed?..."  

The whole gun isn't right...  It's the cheapest gun you can get, and you can easily see where they cut the corners.  Lifetime Guarantee, though.  Good Luck with that.

Edited February 7, 2020 by 98Z5V

[ApexJunky]

So. To retain the 7” receiver extension perform the following tasks and source these parts:

Rotate receiver extension in another turn (with the retainer removed) check for interference with upper receiver. If it works, trim/notch as required.

Springco Orange

KAK 2.5” 5.3oz buffer

Open 0.070” gas port somewhere from .080” to .085”

...or sell it and buy a real rifle 😆

[ApexJunky]

I kid... It’s always cheaper to keep her!!

[jtallen83]

2 hours ago, ApexJunky said:

Springco Orange

KAK 2.5” 5.3oz buffer

Price those parts and compare to the Armalite kit before you buy, the kits are a known reliable system.

https://www.armalite.com/product/ar10rekit01-6-position-receiver-extension-kit/

Still curios if the bolt catch will engage the bolt and not just the carrier when hand cycling?

[unforgiven]

3 hours ago, ApexJunky said:

I kid... It’s always cheaper to keep her!!

Sometimes you have to cut your losses. 

[shooterrex]

There is 1 more thing I noticed. The gas tube doesn't come into the middle of the cam pin cutout. Armalite has the proper length gas tube. I started with a PA10 as well. A learning experience for sure.

[ApexJunky]

Forgot to add this to a previous post:

 

[jtallen83]

1 hour ago, ApexJunky said:

Forgot to add this to a previous post:

 

You won't get the catch to engage the bolt face with that buffer in an AR-15 extension. My advice is get the Armalite kit and cross off buffer system as a possible issue.

[98Z5V]

10 hours ago, ApexJunky said:

Forgot to add this to a previous post:

 

I just re-read this whole thing, looked at what Jim said earlier (that pic you posted up through the magwell, bolt locked back), and was coming in here to ask you if they stuck a 3.250" AR15 buffer in there...  

Those stupid fuckers.

Edited February 10, 2020 by 98Z5V