Question AR9 pistol builds?

Chwillbill68

Chwillbill68

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Would anyone be willing to post some pics of their 9mm AR pistol or rifle builds. I am thinking about making one, but I am a very visual person and get a lot of ideas from what I see. Also any things that have made you set-upd work. I heard that these can be pretty tricky to tune once you get it together.
 
Straight blow back kinda sucks. I wished they had the delayed blow back few years ago.
I got picks in AR build thread still pretty
 
Including parts list

Space Blaster

Im bored and its raining I did this 1 few years back- havent found a red that will stay on the brake Still working on a electric blue for the upper I like. Its a blast to shoot and accurate out 50yds minute-O-man. Which is all Ive attempted. 9mm Faxon barrel Rainer Arms bolt Odin Works upper...
www.patriotgunbuilders.com www.patriotgunbuilders.com
 
Stephen G said:
Including parts list

Space Blaster

Im bored and its raining I did this 1 few years back- havent found a red that will stay on the brake Still working on a electric blue for the upper I like. Its a blast to shoot and accurate out 50yds minute-O-man. Which is all Ive attempted. 9mm Faxon barrel Rainer Arms bolt Odin Works upper...
www.patriotgunbuilders.com www.patriotgunbuilders.com
Click to expand...
Awesome I will check this out.
 
blowback9.wordpress.com

Blowback9.com

No-BS information for the 9mm AR.
blowback9.wordpress.com blowback9.wordpress.com

blowback9 is the Bible for AR9, must read for all AR9 knowledge.

AR9 with blowback9 recommended budget parts w/ 80% etch lower
PhotoRoom-20240109_222928.png

AR9 MAT-9 buffeless upper w/ 80% lower.
PhotoRoom-20240125_140145.png
Before paint
PhotoRoom-20240106_132949.png
 
I'll need to do some research to find all the parts I used. Rifle, not a pistol. The upper was a complete Aero upper with LRBHO. I think the lower was a general parts kit and the trigger a PSA drop in. I have not fired it a ton, but I have not had issues with it. No tuning needed.

LeftSide.jpg
RightSide.jpg
 
This has me interested in building a braced AR9 pistol. I see some uppers offered, Can you use a regular AR lower? And if so do you need a mag block to accomodate the 9mm mag, presumably a Glock mag?
 
mac66 said:
This has me interested in building a braced AR9 pistol. I see some uppers offered, Can you use a regular AR lower? And if so do you need a mag block to accomodate the 9mm mag, presumably a Glock mag?
Click to expand...

Yes. Two approaches to do this.

There are magazine fillers (a MagPul with the spring and follower replaced) like this one from CMMG
Adapter, Magazine, 9 AR Conversion, 10-30rd, 2-Pack | CMMG - AR 15 and AR 10 Builds and Parts

There are magazine adapters, that go inside the regular AR lower, like this one from Stern
MAG-AD9

I tried both and like the Stern approach on the ground that I have regular AR lowers as well as Glock magazines. It works well, has a metal ejector, and bolt hold-open bell-crank built in. It is a bit pricey, but adds all the function to an otherwise stock AR lower in one move. You can also convert the lower back in a few minutes.

When doing either approach, you should also limit the travel of the buffer. This is more for reliability and preventing spent brass from getting into the fire control pocket in the lower. There's a long buffer (from the Colt 9mm AR) or the use of a spacer in the buffer tube so the breech face can only travel back far enough to reach the bolt hold-open.
 
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My configuration of choice: The rifle on the right in the photo. 16" 9mm carbine using the Stern magazine adapter to take 15rnd 9mm Glock magazines. I also used an upper from Stern, but others will work just as well. (It was a package deal from Stern, but you can buy the adapter separately if you already have your upper.) You just need to be sure your bolt is set up for use with a fixed ejector on the lower, which mirrors what most AR-9 lowers have added to them.

20230417_154311.jpg



The adapter installed in an 80%, regular lower.

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As you can see, the adapter provides a feed ramp, last-round hold open, and it's own magazine catch. The AR's magazine catch is used as part of the means to hold it in, but set screws on the adapter press against the inside of the AR magwell to hold it in place. (If you accidentally push the normal mag release, the whole adapter doesn't just fall out the bottom of the AR.)

The placement of the mag release felt a little goofy at first. But after using it with long stick magazines, it made perfect sense. If you grab the body of the magazine with your left hand, your left thumb ends up right on top of the mag release button. You just get used to not dumping the empty mag with your right hand fore-finger.
 
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I suppose I could also get someone to either print a 3D mag well adapter for the glock mags or I could buy a 3D printer and print an AR9 lower myself. Whatever is cheapest and easiest is best. For some reason AR9 lowers seem to be way more expensive than regular AR receivers. Just toying with the idea of a 9mm AR.
 
mac66 said:
I suppose I could also get someone to either print a 3D mag well adapter for the glock mags or I could buy a 3D printer and print an AR9 lower myself. Whatever is cheapest and easiest is best. For some reason AR9 lowers seem to be way more expensive than regular AR receivers. Just toying with the idea of a 9mm AR.
Click to expand...

I wouldn't... the mag well adapter does not lend itself well to 3D printing. It's a mix of aluminum and steel parts.

The least expensive option is to use the magazine fillers on regular MagPul magazines. They do work. I just don't know how long they will last since the ejector is plastic. But, they are relatively inexpensive if you already have the magazines and a normal AR lower.

The adapter is cheaper in the long run if you have an AR lower and a bunch of suitable pistol magazines to work with, since a stack of good pistol mags can cost more.

That was the determining factor for me.... I had the magazines for the G19 and they are common to both the pistols they were designed for and the carbine they get used in. ;)
 
mac66 said:
For some reason AR9 lowers seem to be way more expensive than regular AR receivers. Just toying with the idea of a 9mm AR.
Click to expand...
We had many discussions about the reasoning behind AR9 cost. I believe it is due to the economy of scale. AR9 is a niche market and return on investment takes more units of sale. So, to justify ROI vendors will increase unit price.

Some food for thought...

Both AR9 lower vs magwell adopters have pros and cons. These are some of my reasons for AR9s direction.
I had Endomag inserts with ejector [see MAT9 above], and they work great the only issue was loading was difficult. I found 2nd Colt Mag adopter on sale for $60 so now both AR9s have Colt Mag.

Photoroom-20240502_120525.png
 
I've had a number of guns without a last round bolt open feature or ones that simply don't work sometimes if they do. It's no big deal to me.and not something I depend upon even if the gun has it or is supposed to have it.

The way I figure if I was in a situation that I needed more than 15, 20 or 30 rounds and the bolt didn't hold open when the mag was empty I got bigger problems and the LRBO isn't going to make any difference.
 
I went with EndoMag inserts first, but settled on the Stern Defense adapter for Glock mags.

I have a crap-ton of Glock mags, and a bunch of KCI clones. So far, I cannot really tell a difference between their performance, but some complain that the KCI springs get weak and cause malfunctions. Only more rounds and time will tell, but springs are reasonably priced and readily available.
 
Let me toss some of my thoughts in. Look for AR lowers that are made for pistol magazines. I bought two types of adapters over a decade ago and they are a bandaid not a real solution. The prices and availability are good now, $130 to a little over $200 for Glock comparable lowers. Get a heavy buffer , 5.5 oz to 6.5 oz for 9 mm ammo. Get a decent brake ! Figure out what ammo runs best, for me it's 124gr FMJ projectiles. Don't expect to hit anything past 100 yards. It's a 50 to 100 yards gun !!! Have fun šŸ˜
 

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