Ar9 build clarification.

NCLivingBrit

NCLivingBrit

Well-Known Member
2A Bourbon Hound 2024
2A Bourbon Hound OG
Supporting Member
Multi-Factor Enabled
Joined
Dec 16, 2016
Messages
22,639
Location
Reidsville NC
Rating - 100%
71   0   0
So I want a 9mm AR pistol to go with the 300BO one for cheap plinking. I'm probably going to go dedicated lower for Colt Mags w. the usual brace dealt etc but I'm a bit confused about uppers.

https://www.bearcreekarsenal.com/bc...zed-heavy-barrel-9mm-1-10-twist-w-7-mlok-rail

Are they still mag dependent? I was looking at the Bear Creek since I like my 300 upper from them and I can't fathom if it will work with a Colt mag or Glock mag or both?

Little help?
 
Last edited:
Uppers are not mag dependent. You can use a normal AR upper if you want, but the 9mm specific uppers will have a smaller ejection opening. There is some mag related issues depending on your bolt. I think MOST bolts now are compatible with both glock and colt mags, but I would double check that.

Edit - couple of things: that upper says its 9mm, but lists a pistol gas system. 9mm doesn't use a gas system, so maybe/hopefully that is just a typo. Also - I dont see a 9mm bolt listed in the BCG list - so I'm not sure if it would work.
 
Last edited:
Geerubb said:
Uppers are not mag dependent. You can use a normal AR upper if you want, but the 9mm specific uppers will have a smaller ejection opening. There is some mag related issues depending on your bolt. I think MOST bolts now are compatible with both glock and colt mags, but I would double check that.

Edit - couple of things: that upper says its 9mm, but lists a pistol gas system. 9mm doesn't use a gas system, so maybe/hopefully that is just a typo. Also - I dont see a 9mm bolt listed in the BCG list - so I'm not sure if it would work.
Click to expand...

The title says blow back gas system, which essentially means no gas system. One is a typo, probably the pistol length. I'd call and verify before ordering.
 
As said above. I've always thought a standard AR upper is better as the larger opening can help cycling to make sure cases extract as easily as possible. Downside is it doesn't look as Gucci as a small opening (to some).
 
Last edited:
JRHorne said:
As said above. I've always thought a standard AR upper is better as the larger opening can help cycling to make sure cases extract as easily as possible. Downside is it doesn't look as Gucci as a small opening (to some).
Click to expand...

I actually really like the big magwell with the Colt Mag look. Retro and such. I may go with a mag block so it can share my 300BO pistol lower.
 
NCLivingBrit said:
Yeah but at the price they want for those things, plus the cost of a donor Pmag it's pretty pricey.
Click to expand...
But if you already had PMags, and only wanted a couple, it’s a much easier solution than a mag block and a handful of colt mags (if you didn’t have them already).

I’ve never used one, but a lot of people don’t even know it’s an option. I was just putting it out there. :D

I run Colt mags in both of mine. One with a Hahn dedicated mag block and one with a CMMG colt-mag lower.
 
BigWaylon said:
But if you already had PMags, and only wanted a couple, it’s a much easier solution than a mag block and a handful of colt mags (if you didn’t have them already).

I’ve never used one, but a lot of people don’t even know it’s an option. I was just putting it out there. :D

I run Colt mags in both of mine. One with a Hahn dedicated mag block and one with a CMMG colt-mag lower.
Click to expand...

The Hahn block is supposed to be pretty sweet, but pricey. I think I'll likely go with the Colt Mags, I'd rather spend a bit more up front and be able to pile mags deeper cheaper.

Just got figure the most reasonable decent mag block.
 
Last edited:
NCLivingBrit said:
The Hahn block is supposed to be pretty sweet, but pricey. I think I'll likely go with the Colt Mags, I'd rather spend a bit more up front and be able to pile mags deeper cheaper.

Just got figure the most reasonable decent mag block.
Click to expand...
Yes, the Hahn is pricier than most. Mine was a dedicated SBR build so I wanted it done right up front and not worry about it.

Hahn, if I remember correctly, has 3 different styles...top, bottom and dedicated. Mine is the dedicated style.

Lots of positive reviews on the PSA brand, but they were out of stock when I looked the first time I saw this thread. I also with PSA would make more of their PSA/Metalform mags, but they have no plan to do so.
 
BigWaylon said:
Yes, the Hahn is pricier than most. Mine was a dedicated SBR build so I wanted it done right up front and not worry about it.

Hahn, if I remember correctly, has 3 different styles...top, bottom and dedicated. Mine is the dedicated style.

Lots of positive reviews on the PSA brand, but they were out of stock when I looked the first time I saw this thread. I also with PSA would make more of their PSA/Metalform mags, but they have no plan to do so.
Click to expand...

I'd really like a top loader, just not enough to pay Hahns prices lol

Im a bit soured on PSA right now what with two duff bits in a single build kit, but needs must.....
 
Correct me if I'm wrong but if an AR bolt is compatible with Glock mags it should work with Colt Mags because the difference is they have to trim it a little thinner for the tighter Glock feed lips?

Apparently not. Bear Creek says their uppers are Glock mag only.
 
Last edited:
I went the Endomag route and haven't been disappointed. Gave me a use for the PMags I had. I hate them for 5.56.
 
Last edited:
OK, so apparently I either have to up my budget or use Glock mags. Or as half of you suggested, Endomag.

Are they compatible with most 9mm bolts? Their website is a bit vague. I'd really like to use the cheap Bear Creek upper with bcg since this is mostly a cheap shooter, just not sure the mags are compatible. If I can't figure it out I'll write to both companies, but Bear Creek take a while to respond.
 
Last edited:
I've used gen2 pmags with endomags on a bunch of different lowers and they have always worked great. They are relatively pricey but if you already have spare pmags then it's much cheaper than a complete lower. Wait for a sale on brownells or optics planet.
 
i have 2 PSA lowers and have had no problem with them except I wish they locked open after the last shot.
 
Sevenshot said:
I've used gen2 pmags with endomags on a bunch of different lowers and they have always worked great. They are relatively pricey but if you already have spare pmags then it's much cheaper than a complete lower. Wait for a sale on brownells or optics planet.
Click to expand...
KnotRight said:
i have 2 PSA lowers and have had no problem with them except I wish they locked open after the last shot.
Click to expand...

Mostly I was confused/concerned about the bcg and it's compatibility, that seems to be the big sticking point with about everything AR9.

As for the LRBHO I'm used to AKs. I can live without it.
 
Last edited:
Both of my bolts came from PSA. I did order a Colt bolt by accident from another vendor and it would not work in the PSA lower. They said that they would have to machine some of the bottom of the bolt to work. I just sent it back for a refund. I have had not bad expenses with PSA except one of their AR-upper the gas block came loose.
 
KnotRight said:
Both of my bolts came from PSA. I did order a Colt bolt by accident from another vendor and it would not work in the PSA lower. They said that they would have to machine some of the bottom of the bolt to work. I just sent it back for a refund. I have had not bad expenses with PSA except one of their AR-upper the gas block came loose.
Click to expand...

I got a seriously crooked mag button and a bad end plate in my last kit from them and they wanted an inordinate amount of BS to replace them so I'm eschewing them for the moment.

It's starting to look like my choice is cheap Glock mag build or more money for Colt or Endomag.
 
Last edited:
I know you figured it out, but I’ll post this just to add to the thread.

Here’s the CMMG 9mm lower:

2BAD5B55-1B7D-49FF-A1FB-9F6E4E2E19F2.jpeg

And here’s a standard lower with a Hahn dedicated mag block:

66DB35DC-8467-42CA-BC77-A38F7A96B318.jpeg

Both function the same for me, with LRBHO that works...colt mags.
 
BigWaylon said:
I know you figured it out, but I’ll post this just to add to the thread.

Here’s the CMMG 9mm lower:

View attachment 183818

And here’s a standard lower with a Hahn dedicated mag block:

View attachment 183819

Both function the same for me, with LRBHO that works...colt mags.
Click to expand...

Very cool info. Now if I can find an upper and BCG in the same price bracket as the Bear Creek that will work with Colt mags
 
I've been thinking of doing a 9mm too, because I'd have a hard time doing 100yds on steel in my back yard, but 25 with a pcc and the neighbors don't care.
also, why not? I could toss a can on it and hardly disturb anybody all night long. 9mm would only cost me about 1/3 what it would cost running my 300 with a can, and i could do it up close.

However, I just don't see the point of a pcc with a barrel that's shorter than some of the pistols I have. makes no sense to me.
Then again, if i start building ARs in yet another caliber, that's even more spare parts that have to be built into rifles at a later date...
 
DrScaryGuy said:
I've been thinking of doing a 9mm too, because I'd have a hard time doing 100yds on steel in my back yard, but 25 with a pcc and the neighbors don't care.
also, why not? I could toss a can on it and hardly disturb anybody all night long. 9mm would only cost me about 1/3 what it would cost running my 300 with a can, and i could do it up close.

However, I just don't see the point of a pcc with a barrel that's shorter than some of the pistols I have. makes no sense to me.
Then again, if i start building ARs in yet another caliber, that's even more spare parts that have to be built into rifles at a later date...
Click to expand...
Cause they are cheap to build, shoot, accurate and just fun as heck to shoot. What else you need? ;)
 
Amps 13 said:
Cause they are cheap to build, shoot, accurate and just fun as heck to shoot. What else you need? ;)
Click to expand...
you might have convinced me. I had actually wanted to do a spike's snowflake with a law folder and a tailhook mod 2 for a 9mm pcc with a dolos takedown hosting a 6" barrel with a rail wide enough to set a suppressor in. I've got most of what i need already...
 
DrScaryGuy said:
you might have convinced me. I had actually wanted to do a spike's snowflake with a law folder and a tailhook mod 2 for a 9mm pcc with a dolos takedown hosting a 6" barrel with a rail wide enough to set a suppressor in. I've got most of what i need already...
Click to expand...
Worst thing that happens is it’s not for you and you sell it on here.
 
NCLivingBrit said:
Oh that note, anyone ever heard of these?

https://www.tnarmsco.com/tac-9-stripped-receiver-glock-mag-compatible/
Click to expand...

I wouldn't use a polymer lower for anything stronger than a 22lr. Maybe the design/tech has matured since they were all breaking off at the buffer tube and the pivot point, but i'm still not interested.

I think direct blowback bolts like many ar9 use aren't known for being especially soft either. with a 5.56, the chamber is locked and the bolt carrier is stable until pressure starts to drop a bit. 9mm don't usually do that.
I could be wrong though, this is getting out of my area.
 
DrScaryGuy said:
I wouldn't use a polymer lower for anything stronger than a 22lr. Maybe the design/tech has matured since they were all breaking off at the buffer tube and the pivot point, but i'm still not interested.

I think direct blowback bolts like many ar9 use aren't known for being especially soft either. with a 5.56, the chamber is locked and the bolt carrier is stable until pressure starts to drop a bit. 9mm don't usually do that.
I could be wrong though, this is getting out of my area.
Click to expand...

I'd heard something along those lines but the source wasn't ideal, but it makes sense.
 
You must log in or register to reply here.
Back
Top Bottom