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Building .308 Lower Better Than Hawaii?


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Greetings,

Turned 50 this year.  Was going to Hawaii to celebrate, Covid hit, the powers-that-be in Hawaii freaked out and instituted 14-day quarantine for visitors to the islands, trip had to be cancelled.  So now I'm putting the money towards my first .308AR build (lower only, upper is already pre-assembled; more on that below).

Quick background: Built my own AR-15 upper (already had a complete rifle from a previous purchase; just added the upper I built).  It actually worked first shot!  Whoo-Hooo!  Anyway, point being I have the tools, I can follow assembly instructions, and I'm not put off at the idea of building my own.

Overarching goal in choice of parts below: Ergonomics, easy to reach, easy to manipulate, broad control surfaces but without being so large as to risk accidental activation, economy of motion in manual of arms.

*** Not all of the following are questions for which I'm seeking answers.  I just wanted to be exhaustive in listing all parts under consideration in case anyone with more experience sees a glaring compatibility issue I'm not aware of and wouldn't even know to ask about.  The biggest obstacles I'm running into are compatible mag release, bolt catch release, and safety selector choices.  I've reached out to manufacturers with these questions without responses; presumably they're very busy and/or understaffed (Covid).  Thus I've turned to this forum for help.  ***

 

Upper: Already purchased a Primary Weapons Systems MK218 MOD 1-M Upper in 6.5 Creedmoor.

 

Lower: Intending to purchase an Aero Precision M5 (.308) Stripped Lower Receiver.
            Question: Will this be compatible with the PWS upper?  They both claim to be DPMS; but I've gathered not all DPMS are cross-compatible.  If not, recommendations on a lower?
            Rationale: Why Aero Precision rather than PWS' lower receiver?  I like the extra little touches on the Aero Precision lower (bolt catch release screw rather than a pin, etc.).
                               Reviews indicate it has a relatively broad compatibility with other lower parts, as well.

 

Buffer Tube: Intending to purchase a Patriot Ordnance Factory, Enhanced Anti-tilt Buffer Tube, .308, Black Finish
                        Question: Any know issues using this Buffer Tube with an Aero Precision M5 (.308) Lower Receiver?
                        Rationale: Intending to purchase a CTS Engineering AKTIVE Recoil AR-10 Anti-tilt Buffer.  It requires a tube with interior depth of 7.75".  The POF tube satisfies that requirement.

 

Buffer: Intending to purchase a CTS Engineering AKTIVE Recoil AR-10 Anti-tilt Buffer.

 

Buffer Spring: Intending to purchase a Tubb Precision AR-10 Stainless Steel Buffer Spring.
                          Rationale: CTS Engineering highly recommends the use of this spring in conjunction with their buffer.  I've used said spring in its AR-15 variant for my current rifle.  Happy with it.

 

Stock: Magpul PRS GEN3 Precision-Adjustable Stock.
            Question: Any issues fitting to a Patriot Ordnance Factory, Enhanced Anti-tilt Buffer Tube, .308?
            Rationale: Already have one on current rifle.  I like the adjustability, I'm familiar with it, it works for me.

 

Castle Nut/Endplate: Intending to purchase a Primary Weapons Systems Ratchet Lock Castlenut and Endplate.
                                      Question:
Any compatibility issues with a Magpul PRS GEN3 Precision-Adjustable Stock?

 

Trigger: Intending to purchase a TriggerTech AR10 Adaptable PVD Black Curved Trigger.
               Question: Any issues with fitment inside an Aero Precision M5 (.308) Lower Receiver?
               Rationale: I want an adjustable pull weight trigger.  I like what I've read and seen about the TriggerTech.  This model claims to be specifically built for the AR-10 platform.

 

Grip: Magpul MOE-K2+ Grip
         Question: Any issues with fitment to an Aero Precision M5 (.308) Lower Receiver?

 

Trigger Pins: Intending to purchase Strike Industries Antiwalk/Antirotation Trigger/Hammer Pins.
                        Question: Will these fit an an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if they don't?
                        Rationale: It's my understanding it's highly recommended or even required by some manufacturers that cassette triggers be secured with antiwalk/antirotation pins.

 

Pivot and Takedown Pins: Intending to purchase Strike Industries AR-10 Shift Pins.
                                               Question: Appear to be made for the AR-10 platform.  Will these fit an an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if they don't?

 

Bolt Catch: Intending to purchase a Geissele Maritime Bolt Catch.
                     Question: Will this fit an Aero Precision M5 (.308) Lower Receiver?  Even if it fits, does it work well in .308ARs?  Other recommendations if it doesn't?
                     Rationale: I like the ergonomics of the design, easy reach with left index finger.

 

Magazine Release: Intending to purchase a Strike Industries AMBI Magazine Release.
                                  Question: Will this fit an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if it doesn't?
                                  Rationale: I'd like to have ambidextrous mag release capability but low-profile to avoid accidental release.

 

Magazine Release Button: Intending to purchase a Battle Arms Enhanced Magazine Release Button.
                                                Question: Will this fit an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if it doesn't?
                                                Rationale: My understanding (which, of course, may be wrong) is the MRB on an AR-10/.308AR needs a little extra height.  This seemed to fit the bill and I like the design.

 

Safety: Intending to purchase a Strike Industries Strike Switch.
             Question: Will this fit an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if it doesn't?

 

I think that about covers it.

Thank you in advance for your patience in reading through this post and for any advice, insight, guidance, or help you can provide.  I'm in the early stages of gathering parts (aside from the upper which is already on order) so there's still plenty of time for me to change selections based on recommendations I receive here.  I'm just looking to avoid buying a part, discovering it doesn't fit/isn't compatible, only to have to return it and face further delays; especially with so much being out-of-stock and on backorder.  Hmmm...I wonder why 🤔  All the same, would still like to get it built before election night...:paranoid:

Cheers,

~ Sir John of Dough

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4 hours ago, Sir John of Dough said:

Pivot and Takedown Pins: Intending to purchase Strike Industries AR-10 Shift Pins.

 

                                               Question: Appear to be made for the AR-10 platform.  Will these fit an an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if they don't?

 

Bolt Catch: Intending to purchase a Geissele Maritime Bolt Catch.
                     Question: Will this fit an Aero Precision M5 (.308) Lower Receiver?  Even if it fits, does it work well in .308ARs?  Other recommendations if it doesn't?
                     Rationale: I like the ergonomics of the design, easy reach with left index finger.

Stick with Aero Precision for the pivot and takedown pins - they're longer than standard DPMS-based LR-308 parts, and work with their lower receiver. 

The Geissele Maritime Bolt Catch is very specifically an AR15 part, and will not work in a .308AR platform.  Stick with either the Aero bolt catch (designed for their own lower), or try to contact PWS and see if they know if their own bolt catch will work in an Aero M5 lower (since they designed that for their own upper).  Hope that makes sense.

If it was my build, I'd run the Armalite EA1095 spring in it. 

Let us know if that PWS upper really works with the Aero M5 lower - I don't think anyone else here has done that combo before.  I'd get the lower in, ensure fitment, before you progress any further.

Edited by 98Z5V
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I looked into your buffer selection, and they never do list the buffer weight.  That's the most important part of building one of these.  I don't care how fancy their buffer looks - you don't complicate shiit with complicated shiit.

If that buffer doesn't weigh 5.4oz, maybe more, it's not gonna work right.  If it's lighter - then they're just selling fancy buffers for .308ARs, and they're trying to make "the fancy make up for real buffer weight."  Call them, see what it weighs. 

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98Z5V,

Thank you very much for your advice regarding the pivot/takedown pins and the Geissele Maritime Bolt Catch; duly noted.

Yeah, CTS doesn't list the buffer weight.  I've emailed them previously with no response.  Next is a phone call.

I intend on taking my upper to the shop to ensure fitment with the Aero Precision M5 lower before committing to the purchase (when they finally get them in stock <queue Jeopardy waiting music>).  If I do settle on the Aero M5, I'll be sure to post a follow up.

Thank you very much for the reply and advice; much appreciated.

Cheers,

~ Sir John of Dough

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Received a response back from Aero Precision regarding fitment of aftermarket parts in their M5 lower receiver.  Will paste here but also in the .308AR Parts forum for easy reference should anyone else have similar questions regarding parts compatibility.

"Due to the non-standardized platform, I cannot guarantee that any other manufacturer's AR10/AR308 product will work in our M5 platform. The listed bolt catches are all AR15 sized (edit: I had inquired after compatibility of Strike Industries' Enhanced Bolt Catch and Extended Bolt Catch), and we have an M5 bolt catch that will work specifically for the wider area of the receiver so the AR15 sized bolt catch will not work and I can only guarantee that our M5 bolt catch will work.

The magazine catch body is mil-spec AR15 sized, so most aftermarket mil-spec sized catch will work you just need an extended mag release button (0.5") and thread it on halfway.

The safety selector is AR15 mil-spec sized so most mil-spec sized ambi safety will work.

The Firing Control Group will be the same mil-spec assembly as well, the lower will take trigger/hammer small pins (.154") and most aftermarket mil-spec triggers will be able to fit; I cannot guarantee a 100% chance of fitment for cassette style (drop-in) triggers as sometimes the housing will interfere with fitment in our trigger well. Let me know if you have any other questions or concerns."

Best Regards,
Cong Le
Support team,
Aero Precision

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15 hours ago, Radioactive said:

Well I’m shocked to hear that!:hail:

If it was only up to Drew @imschur, I think that's the way it could be - I think he has a Man-Crush on me.  A Bro-Mance.   :thumbup:

@Robocop1051, @edgecrusher, and @Matt.Cross got tired of my free ride, and made me start producing, or get out...  They're Hell to work for...   :banana:

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9 hours ago, 98Z5V said:

If it was only up to Drew @imschur, I think that's the way it could be - I think he has a Man-Crush on me.  A Bro-Mance.   :thumbup:

@Robocop1051, @edgecrusher, and @Matt.Cross got tired of my free ride, and made me start producing, or get out...  They're Hell to work for...   :banana:

Well you can’t post for free forever! I realize the rest of us all got our own special rate for posting so no one is the same but this place is costing me an arm and a leg along with all the shiit I bought just because of you enablers. :thefinger:

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15 hours ago, Radioactive said:

Well you can’t post for free forever! I realize the rest of us all got our own special rate for posting so no one is the same but this place is costing me an arm and a leg along with all the shiit I bought just because of you enablers. :thefinger:

You may not realize it, but you actually subsidize what it takes to keep me on payroll.  I actually get paid nothing - but it takes alot to keep me here when I go off on a dumbass - and that's where the "value" comes in...   :thumbup::laffs:  I've launched some pretty legendary ass-reamings here, which further caused Drew to directly shiit a Rabid Monkey straight out of his ass...   It's everything the other guys here can do, just to keep me around...  and NOT be Banned...  :banhim:

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@98Z5V I use all my going of on dumbasses for work. I’m pretty calm everywhere else.

8 hours ago, 98Z5V said:

Drew to directly shiit a Rabid Monkey straight out of his ass...  

Gotta watch out for those rabid monkeys! Don’t get yourself banned this place wouldn’t be the same. It would move on just like life but it would definitely be different.

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  • 2 weeks later...
On 7/22/2020 at 3:32 PM, Sir John of Dough said:

Castle Nut/Endplate: Intending to purchase a Primary Weapons Systems Ratchet Lock Castlenut and Endplate.
                                      Question:
Any compatibility issues with a Magpul PRS GEN3 Precision-Adjustable Stock?

I have one on my ar-15. It came loose, contacted pws, they replaced it free of charge with questions asked. I won't run it in the future on my builds.

Quote

Trigger Pins: Intending to purchase Strike Industries Antiwalk/Antirotation Trigger/Hammer Pins.
                        Question: Will these fit an an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if they don't?
                        Rationale: It's my understanding it's highly recommended or even required by some manufacturers that cassette triggers be secured with antiwalk/antirotation pins.

I use these on all my ar platforms. No tool required = perfect in my book. And yes it fits the M5 lower.

Quote

Pivot and Takedown Pins: Intending to purchase Strike Industries AR-10 Shift Pins.
                                               Question: Appear to be made for the AR-10 platform.  Will these fit an an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if they don't?

Stick with aero, I went 2a armament titanium and had to modify to fit the M5 lower.

Quote

Safety: Intending to purchase a Strike Industries Strike Switch.
             Question: Will this fit an Aero Precision M5 (.308) Lower Receiver?  Other recommendations if it doesn't?

This will fit the M5 lower as it doesn't have a shelf, and one of my favorite safetys.

 

Also to add I run a vseven S7 tool steel bolt catch, it's quite bitchen and fits the M5.

Edited by CatFood
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On 8/11/2020 at 6:06 PM, CatFood said:

I have one on my ar-15. It came loose, contacted pws, they replaced it free of charge with questions asked. I won't run it in the future on my builds.

CatFood,

Thank you very much for the input.  Much appreciated.

Good to know about the PWS ratcheting castlenut issue.  Any recommendations on a preferred castlenut and endplate?

I'll look into that vseven S7 tool steel bolt catch.

Parts are slowly trickling in.  Have maybe about half of them now.  Once it's all received and assembled I'll be sure to update.

Thanks again for the great answers 😀 

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19 hours ago, Sir John of Dough said:

Good to know about the PWS ratcheting castlenut issue.  Any recommendations on a preferred castlenut and endplate?

Any regular old non-fancy castle nut and endplate that you can stake properly. 

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