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· Registered
394 Posts
Discussion Starter · #1 ·
I've always liked the AR-15 platform and want one (who doesn't?!). However, I've always kinda of felt 'meh' about the .223/5.56 NATO round and liked the 7.62x39 cartridge more. After doing some research about the .300 BLK cartridge I got excited, really excited. To put it short, it's everything I like in the 7.62 but in the size of the 5.56, perfect in my opinion. Considering the .300 BLK and 5.56 stuff are compatible (mags/receiver), it makes it even more simple.

Since I never plan to use the 5.56 round, I'd like to save some money by only buying what I need instead of buying a complete AR-15 and replacing pieces (upper/barrel). Not to mention I'm also really interested in building a gun "from scratch", to make it really feel unique and personal to me.

That said, I'm still somewhat new to all this, especially in the AR world. Then you have all the legal mumbo jumbo (registering it as a pistol or a rifle), which I don't want any problems with of course.

I'm curious if anyone else has built their own AR-15 (any caliber) and perhaps some advice. I know there are a lot of good companies that make quality parts so I'm not really worried about that as much as what do I need as a build list. In my mind it's something like "lower receiver, upper receiver, barrel, dust cover, mag, stock..." but I feel like it has to be more than just that. Then you have the compatibility of parts and which gas systems.

I guess some questions I have are (and forgive my ignorance):

  • What are the important pieces I need?
  • What are good optional pieces that might come in handy?
  • Should I get a complete lower or a stripped one?
  • Should I file it as a pistol or rifle (or rather what are the pros/cons)?
  • What is the gas system stuff all about?
  • Any companies to stay away from?

Any of you AR guys have some advice, whether it's what to get or avoid, tips on assembly, anything would be welcome! Thanks in advance! :biggrin2:

· Super Moderator
19,552 Posts
I've built a few.

Lots of Ar stuff.
Lots of rebarrels to .300 AAC on REm 700's, Savages and even some Model 70's.

One bit of advice.

Get a heavy barrel. AAC had issues with the Model 7 Remington that they marketed. They tried to keep it light and used a small diameter barrel. I knew right off it would have issues, I even talked to Robert Silvers (creator of the Blackout) about it and he said that it was a marketing decision to keep the gun light.
It works great unless you hand a .30 cal suppressor off of it and that itty bitty barrel just cant take it, point of impact wanders all over the place.

If you want a nice compact package and intend on supressing it, 8-9" is all you need. Get a forearm that is big enough to allow the suppressor to be inside of it,and with the can on it it wont be any longer than a standard 16" or 20" rifle.

The Blackout dosent really need anymore than 6" of barrel for a complete burn, so 8-9 is plenty.

Of course, you'd have to SBR the lower.

· Registered
329 Posts
Consider a 6.8SPC AR. You can find ammo becaus it is a chamber that is gaining ground in the market: Wally world carries it now.... But not so widely used that you can find ammo if you look hard enough.

Also, what is your budget and what are you going to be using it for?

If you are looking for a good 300-400yrd capable round the 6.8 will fit the bill. If you think, and I mean really think, you will need knock down power out past 400yrds then go 300 something or another... I considered a .50beuwolf but I couldn't find as much support for that round as I did for the 6.8 and the 6.8 is a balistic projectile.

If you want to go the lightweight and cheaper route get any of the poly lowers (New Frontier, Omni, etc) and go from there. Last I checked Joe Bobs had NFL's for $109 shipped minus the stock kit. $159 shipped will get you a complete NFL with stock kit. I personaly went with the prior and added a MOE stock over the regular one so it is mil-spec.

· Registered
1,106 Posts
If you are new to this, and you want to build your first AR, I would recommend buying a complete upper, and only building the lower. As far as building the lower, Buy a stripped lower, lower parts kit (cmmg is good), and a buffer tube/stock kit. Buy a vice block too, it's much easier to assemble a lower if you can lock it down and have both hands to work with. Chances are you will need to buy the bolt carrier group as well. This is the one place I would (and do on my own builds), go all out. Shell out the cash and just get a BCM right off the bat. They are worth it.

I have had nothing but positive experience with Palmetto State Armory, besides their understandable lead time on orders right now (which is about a week or two to ship some things).

Bottom line is, unless you want to really put up the cash for an outstanding battle rifle from a company such as Bravo Company, my money is on PSA and CMMG for price point meets quality.

· Registered
190 Posts
If you have the change to drop and you only want to cry once, buy a AAC built 300blk upper.

They use premium components like an AAC designed beefed up bolt, also they have knights armament rails and little things like a qd flash hider.

Then you can build a lower to your whims.

This is mine:
AAC / Knights Armament 16" upper
Troy rear
Bcm mod 4 charging handle
Magpul AFG
LRB lower
PSA lower parts kit
Magpul MIAD grip
Magpul ACS stock
Spikes ST-T2 buffer and spikes tube

Sent from my iPhone using Tapatalk, please excuse typos.

· Banned
5,989 Posts
Could just buy a finished 300 AAC rifle from Daniel Defense, too. Might be as cheap and you'll have a great rifle.
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· Registered
394 Posts
Discussion Starter · #13 ·
Wow, thanks for all the helpful comments guys! I really appreciate it and I'll definitely check out the links posted. And undoubtedly, I will be posting pics if it does come to fruition! :yup:

My goal with the AR is perhaps CQC with the option of taking it out to longer range (200-300 yards). For anything past 300 yards, I'm planning on a Remmington .308 or similar with serious glass on top but that's down the road really. As for the AR, I want something fairly lightweight and I do plan on going suppressed eventually, so a SBR style makes sense (two tax stamps to get, fun).

Being fairly new to all this, I don't mind buying some pre-assembled bits like the complete upper. I'll start making a spreadsheet of parts and see what I come up with price-wise and compare to an already assembled .300 BLK AR and possibly reconsider building one if I find one that is perfect and reasonably priced.

I have heard ammo for the 300 is a bit difficult to find but not impossible (I guess it can't be any worse than 9mm/22LR from what I see around here). I will look into the other calibers posted but my main reasoning for the 300 are the ones I listed originally along with the ease of suppression. I feel like the 300 is really what the 5.56 should have been from the start, but well...

· Registered
16 Posts
Actually, the 6.5 Grendel is the cartridge that should replace the 5.56 - but that's another discussion altogether.

I agree with the ideas that:

1. The .300 BLK is the best cartridge in the AR-15 platform overall, if... the gun is a suppressed SBR.

2. It makes sense to buy a complete upper.

I bought a Noveske 8" upper, and put an AAC 762-SDN-6 on it. It's hearing-safe quiet with subsonic rounds. Really quite amazing. Plus, the suppressor can easily mount on my 6.5 Grendel rifle.


· Registered
329 Posts
Ahh yes the 6.8SPC & 6.5 Grendel. 2 very potent options.

I chose the 6.8 for a few reasons, important to me, but not in discount to the abilities of the 6.5.

In searching, I found the parts a bit more easy to come by.

In fact, here is the fruits of my labor thus far..

Start to finish custom build in roughly 3weeks.
PSA SS 18" upper (still in-stock! So hurry!) in 6.8spc
PSA full auto BCG
NF Lower
MOE stock, Grip & Foreguard
BCM Gun fighter mod 3 charge handle
3-10x42 dual illuminated retical

Gun Firearm Assault rifle Trigger Rifle


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