AR9 Build Clarifications

[myn0ck]

Hello,

 

Just starting to get into the AR and PCC world and decided to dive in head first... I'm in the process of building an AR9 from the ground up, even using a 5D jig to mill an Iconic lower.  It probably would've been smarter, being new to AR internals, to start with something already built, but... Nope. :-)

 

At this point (and I'll probably have more questions), but I have a couple of questions that I don't have good answers for yet.

 

1) On my lower, it came with a metal "hook" that looks like its either meant to help guide the bolt or... Do something else.  Based on other pictures, I'm 99% sure we have it installed correctly.  The question is simply... What is it?  What's its purpose?

 

 

2) With my QC10 side charging upper, it has a hole for a gas system?  Why?  Should it be left open or plugged (with a threaded insert that I don't have)?

 

 

Thanks for any help!

 

--m

[BartCarter]

1. The "hook" is the brass ejector.

2. You can leave the gas tube hole alone or plug it, your choice.  It has no function in a blowback AR.

 

I like the lightening cuts! 

[MikieM]

Oh, are you going to have fun. If I had a mill I'd be knee deep in 80% lowers.

Keep us posted.

[Underwood]

subscribed... nice pics 

[myn0ck]

22 minutes ago, BartCarter said:

1. The "hook" is the brass ejector.

2. You can leave the gas tube hole alone or plug it, your choice.  It has no function in a blowback AR.

 

I like the lightening cuts! 

 

Thanks for the quick reply.

 

Brass ejector... Did not guess that. 

 

Knowing that its a blowback operation, I was confused why QC10 even includes the hole in their 9mm side charging upper.  I turned this into a Christmas "father/son" build project while visiting family, so we were able to grind down an appropriate screw to fit and be flush in my dad's shop.  While small, we don't like the idea of a hole that things could get into since my KVP handguard does not fully cover it.  I was also wondering, in general, about gas being able to escape through the hole, or if I'm simply over-thinking in that regard.

 

--m

[myn0ck]

28 minutes ago, MikieM said:

Oh, are you going to have fun. If I had a mill I'd be knee deep in 80% lowers.

Keep us posted.

 

Yeah.  Its been a learning experience, but overall, the 5D Tactical jig was very nice.  I only got the AR15/AR9 package, but its easy enough to get the AR10 pieces later should I decide to go down that path at some point.

 

While I do not have any experience with alternative jigs, I would definitely recommend the 5D Tactical Pro jig.

 

The process mostly went very smoothly, my 2 pieces of advice though are...

 

1) Go slow, even if it means milling less than the hash marks each time.  No need to go fast or rush through.

 

2) Go slow and don't get into a routine.  We made a single mistake when milling, and at the very end of the process.  Luckily it was recoverable, left a couple gashes that are really cosmetic, but we got into a routine of changing the milling depth and squirting some WD40 and milling, and changing the milling depth and squirting some WD40 and milling, and.... Forgot to changing the depth guides!!!  And at the trigger pocket hole stage!!  Pulled it out quickly when it started to chatter.  Got lucky.

 

--m

[myn0ck]

A couple other pictures, just to share.  :-)

• Upper:  QC10 Side Charging
• Lower: Iconic Industries 80% 9mm Instigator Ultralite
• Bolt: Tacom
• Buffer:  Tacom 3-stage
• Stock: Hogue
• Barrel:  KVP 16"
• Handguard:  KVM Carbon Fiber 15"
• Comp:  KVP Linear
• Grip:  BAD-ATG
• Trigger:  Hipertouch 24E

 

Cosmetic Additions

• Strike Industries Selector Switch
• Strike Industries Enhanced Castle Nut
• Strike Industries Ultra Light Pivot / Takedown Pins

 

In regards to the 5D Tactical jig... One other piece of advice that we followed, but is not found in the instructions, is to put some additional tape around gaps to trap shavings and create additional suction for the attached vacuum.

 

[MikieM]

Well done, and I can see you are into light weight components. Me too. 

[myn0ck]

12 minutes ago, MikieM said:

Well done, and I can see you are into light weight components. Me too. 

 

 

Thanks. Gotta get ready for when spring matches start up! 

 

The idea was to put something together following a mixture of "buy once, cry once" & a result that shoots better than I do.  Once (or if) I catch-up to it, then I'll think about appropriate upgrades.

[corny]

I have milled out several lowers with the 5D jig.  They come out as good or better than lowers I have milled out on a vertical mill.  

The cuts are clean and precise. 

Now the only thing you are going to have to contemplate is a larger safe for the other 3 or 4 PCC's you are going to build.

They are too much fun....

[myn0ck]

3 hours ago, corny said:

I have milled out several lowers with the 5D jig.  They come out as good or better than lowers I have milled out on a vertical mill.  

The cuts are clean and precise. 

Now the only thing you are going to have to contemplate is a larger safe for the other 3 or 4 PCC's you are going to build.

They are too much fun....

 

Except for one, thankfully recoverable, mistake of my own, I think it came out very well.  Even though it will rarely be seen, we did clean-up the tooling marks some too as part of de-burring the drilled holes.  Adding something like that to the bit package for a final pass would've been a nice, cherry-on-top, addition.

[myn0ck]

And it's basically done.

 

It's technically able to be shot now after I clean and lube.  That's next on the list, once I find the time around all the holiday activities.

 

Things to do, but won't keep it from being fired...

• Switch out the selector switch with the red Strike Industries
• Take off the grip to tighten that screw that helps reduce rattle
  • Side note... Got lucky with that screw.  It needs to be removed before milling. Luckily figured that out before milling that low!

There are a few things that I found after everything was put together that... could be better.

• This may just be a general AR thing, as it seems to be the same with my Dad's normal AR, but I don't like that the safety cannot be engaged without the bolt cocked
• It is extremely difficult to manually lock the bolt back.  I'm hoping this is on account everything being brand new and not oiled or worn in from shooting any
• The QC10 side-charging upper... I like the look.  I like the concept.  I generally like the product, but the difficulty of manually locking the bolt also showed that the charging handle design may be better if it was more like the Gibbz or NFA uppers, where there appears to be more meat to the handle (even if I think those don't look as good!)

Other tidbits...

• The Magpul Armorers wrench apparently does not work for the KVP barrel nut (had to borrow a 1 1/4" crowfoot)
• The Magpul Armorers wrench does fit the Strike Industries castle nut... But because of the extended end plate, you cannot turn it

 

One last general comment... Coming from a computer system engineer that deals with requirements and customers and such... For the majority of products I bought, and it may be specific to after-market AR parts manufacturers, the impression I have is that there is a problem with providing instructions, of any kind.  Yes, the majority of things can be found via googling, but I don't view that as acceptable.  Definitely not friendly to people starting out and still learning.  Instructions don't even have to be included with the product, a simple go to our website for instructions and tips and guidelines (e.g. torque recommendations) would be quite adequate.

 

 

 

[12Bravo]

The Taccom buffer was designed to minimize movement of the bolt, so locking the bolt to the rear is gong to be difficult at best. The thread about the 3rd stage buffer has some discussion on this. You could purchase the Gibbz latching charging handle and it would work considering the uppers are made by Gibbz, but you are going to find that due to the latching mechanism the surface area is going to be the same as the QC10. 

That is one nice-looking build, congratulations and well done.

[TRUBL]

4 hours ago, 12Bravo said:

The Taccom buffer was designed to minimize movement of the bolt, so locking the bolt to the rear is gong to be difficult at best. The thread about the 3rd stage buffer has some discussion on this. You could purchase the Gibbz latching charging handle and it would work considering the uppers are made by Gibbz, but you are going to find that due to the latching mechanism the surface area is going to be the same as the QC10. 

That is one nice-looking build, congratulations and well done.

Well done build....you will enjoy that for sure........as for lock back on the TACCOM buffer....piece of cake to be honest. Just remove that delrin pad if BHO is important to you. The thickness at the bottom of that carbine tube is 3/4 to 1 inch thick......you will never have an issue there.

[myn0ck]

Thanks for that info on the BHO.  I'll probably test with things as-is and then see if everything still feels and works as good without the delrin pad.  If not, I'll just add it back in!