AR Pistol or not??

[Voldemort]

OP,

I had the same question a while back. After putting together my first one, I couldn't be more happy with my 300blk pistol. Here are some random thoughts and why I went with 300blk AND the pistol platform...

- The 300blk rounds lend themselves well to a short barrel. You'll find that most 300blk ammo will burn the entire gunpowder charge within a 9" barrel. Not true with the 5.56 NATO round. Launching 5.56 rounds from a 9" barrel will result in substantial muzzle flash and pronounced bang.

- The recoil on my 300blk with supersonic rounds feels no different to me than a traditional 5.56 mid-length gas system weapon. Very little muzzle rise and relatively low recoil.

- My particular BCM upper is surprisingly accurate. Almost jaw-dropping accurate. Like we're talking 1MOA or better (within 100 yards anyway). With my Aimpoint on top of this pistol, I can bring the weapon from low/high ready to shooting position, acquire target, and put a round (or 10) exactly where I want it PDQ.

- You can choose to shoot the 300blk in traditional or subsonic velocities. Subsonic is great for suppression and traditional velocity puts the hurt on most prey. You don't have these options with 5.56

- Choosing a pistol platform over an SBR build can give you more flexibility. A pistol, for example can be carried in a vehicle (loaded) in many states (check your local laws). Conversely, these same states may prohibit loaded rifles in vehicles.

- You may also find that hunting with a pistol is allowed in some jurisdictions, whereas hunting with an SBR is not allowed in those same areas.

- 300blk ammo is more expensive than 5.56, but I'm okay with that. Especially considering the aforementioned advantages. This weapon is not for plinking on a sunny weekend afternoon for hours on end.

- My ammo selection is currently Barnes VOR-TX 300 Blackout 110gr TAC. Wicked round. For target practice/training, I typically go with something more affordable (e.g. S&B, Fiocchi, etc.)

WOW, you really tipped the scales toward 300 blk!!!

 

[Disposable Heart]

Did the 9mm AR pistol route. PSA Glock mag, 4.5" barrel, KAK brace. Even after buffer and spring tuning, it still has more recoil than my 8" .300BO with supers or my 10.5" 5.56 with IMI M855. Handled really well, but had a myriad of reasons I didn't see the "AR9 master race" light:
-Too much recoil for the package
-The shorter barrel facilitated a subconscious drive to get a handstop so I would not shoot my hand. Had issues mounting due to flash can and short rail interfering with the bolts for the handstop
-While reliable, it needed a lot of work to get there and still had difficulty after tweaking with wide mouthed (HST) JHP (ran well with Federal Hi-Shok, Golden Saber, etc..., rounded profile rounds)
-Mangled brass no matter what I did (and I handload, so it was a problem)
-My particular model did not have last round bolt hold open, so I developed a training scar with my other ARs of using the charging handle every time instead of the bolt release, took me a lot of time to get back to pressing the bolt release after I got rid of the AR9. I had built the AR9 to be the indoor range trainer, so it saw alot of use
-Broke extractors like candy, 2 in a thousand rounds, compared to nearly 9000 on my 10.5" AR.
-Mags were more expensive for capacity compared to 5.56/.300 mags. While I had a G17 at the time of AR9 ownership, I made the choice to keep the G17 because I could carry it easily compared to the AR9 and have same mag cap with mag change.
-Ammo cost with 9mm was lighter, but capability was greater with my .300.
-Supressed, my .300 was actually quieter than my AR9 wearing a friend's 9mm can and subsonics, the action opening and closing, blowback, etc... just seemed to tip the decible scale in favor of my .300.

Had more ergonomic accuracy and less recoil than a handgun (G17 with 33 round mag) but not nearly as concealable as a proper 9mm handgun. It was handier than even my 8" .300 blackout, but still was too violent in operation, training scars and I didn't see the efficacy of 9mm compared to .300's ability to run deeper penetrating subs or hi vel supers (rifle compared to handgun ballistics).

If I had to do it all over again, I would have bit the bullet and made a adjustable gas 7.62x39, bought a bunch of bolt heads with my ammo savings, and not have the fear in my mind of accidentally swapping 5.56 and .300 mags at the range. With handloading, I could have made 7.62x39 subs and been able to buy cheaper ammo, make "Mexican match" with quality bullets and cheaper steel cases, etc... Tinkerer's dream compared to that AR9.

 

[Voldemort]

I regards to 300 blk barrel, is pistol length gas better that carbine??

 

[hammerd13]

I regards to 300 blk barrel, is pistol length gas better that carbine??

I'd lean towards a pistol length system for 300 blk. Especially when you consider the reduced gas available with subsonic ammo.

Here's a decent article on the subject.
https://www.fogammo.com/blogs/news/why-subsonic-300-blackout-needs-a-pistol-length-gas-system

 

[WebSnyper]

Did the 9mm AR pistol route. PSA Glock mag, 4.5" barrel, KAK brace. Even after buffer and spring tuning, it still has more recoil than my 8" .300BO with supers or my 10.5" 5.56 with IMI M855. Handled really well, but had a myriad of reasons I didn't see the "AR9 master race" light:
-Too much recoil for the package
-The shorter barrel facilitated a subconscious drive to get a handstop so I would not shoot my hand. Had issues mounting due to flash can and short rail interfering with the bolts for the handstop
-While reliable, it needed a lot of work to get there and still had difficulty after tweaking with wide mouthed (HST) JHP (ran well with Federal Hi-Shok, Golden Saber, etc..., rounded profile rounds)
-Mangled brass no matter what I did (and I handload, so it was a problem)
-My particular model did not have last round bolt hold open, so I developed a training scar with my other ARs of using the charging handle every time instead of the bolt release, took me a lot of time to get back to pressing the bolt release after I got rid of the AR9. I had built the AR9 to be the indoor range trainer, so it saw alot of use
-Broke extractors like candy, 2 in a thousand rounds, compared to nearly 9000 on my 10.5" AR.
-Mags were more expensive for capacity compared to 5.56/.300 mags. While I had a G17 at the time of AR9 ownership, I made the choice to keep the G17 because I could carry it easily compared to the AR9 and have same mag cap with mag change.
-Ammo cost with 9mm was lighter, but capability was greater with my .300.
-Supressed, my .300 was actually quieter than my AR9 wearing a friend's 9mm can and subsonics, the action opening and closing, blowback, etc... just seemed to tip the decible scale in favor of my .300.

Had more ergonomic accuracy and less recoil than a handgun (G17 with 33 round mag) but not nearly as concealable as a proper 9mm handgun. It was handier than even my 8" .300 blackout, but still was too violent in operation, training scars and I didn't see the efficacy of 9mm compared to .300's ability to run deeper penetrating subs or hi vel supers (rifle compared to handgun ballistics).

If I had to do it all over again, I would have bit the bullet and made a adjustable gas 7.62x39, bought a bunch of bolt heads with my ammo savings, and not have the fear in my mind of accidentally swapping 5.56 and .300 mags at the range. With handloading, I could have made 7.62x39 subs and been able to buy cheaper ammo, make "Mexican match" with quality bullets and cheaper steel cases, etc... Tinkerer's dream compared to that AR9.

Good info on the PSA AR9. I briefly handled a 2nd gen one at the NRAAM.

I'm interested in a Pistol Caliber AR or proprietary platform such as an MPX, and saw that the PSA AR9 was one of the cheapest, but looks like that comes at a price based on your info. Wonder if the Windham Weaponry or the Freedom Ordnance might improve upon those cons of the PSA, or if not, if it is just worth it to head down the MPX or Scorpion routes?

 

[Areoflyer09]

Good info on the PSA AR9. I briefly handled a 2nd gen one at the NRAAM.

I'm interested in a Pistol Caliber AR or proprietary platform such as an MPX, and saw that the PSA AR9 was one of the cheapest, but looks like that comes at a price based on your info. Wonder if the Windham Weaponry or the Freedom Ordnance might improve upon those cons of the PSA?

Slightly off topic maybe, but the gas system is what makes the MPX a softer shooter and at least part of why it costs more.

If it can be worked out, I’m always happy to let people run my MPX.

 

[WebSnyper]

Slightly off topic maybe, but the gas system is what makes the MPX a softer shooter and at least part of why it costs more.

If it can be worked out, I’m always happy to let people run my MPX.

Was kind of figuring that may be the case as I was typing that. I'm just starting to research. I assume the AR9's are a blow back setup?

I may take you up on that at some point.

How difficult or easy is the MPX to field strip for regular cleaning, etc?

 

[nipprdog]

Good info on the PSA AR9. I briefly handle

I'm interested in a Pistol Caliber AR or proprietary platform such as an MPX, and saw that the PSA AR9 was one of the cheapest, but looks like that comes at a price based on your info. Wonder if the Windham Weaponry or the Freedom Ordnance might improve upon those cons of the PSA, or if not, if it is just worth it to head down the MPX or Scorpion routes?

I've had no problems with my PSA 9 Glock models. Had a 16" version that I put over 1500 trouble free rounds through it. Sold it and got the 8" version pictured on page 3. Over 500 trouble free rounds through it so far.

 

[WebSnyper]

I've had no problems with my PSA 9 Glock models. Had a 16" version that I put over 1500 trouble free rounds through it. Sold it and got the 8" version pictured on page 3. Over 500 trouble free rounds through it so far.

Good to know. Thanks for the info.

 

[Disposable Heart]

Slightly off topic maybe, but the gas system is what makes the MPX a softer shooter and at least part of why it costs more.

If it can be worked out, I’m always happy to let people run my MPX.

This. People wonder why dedicated subgun designs cost more and its entirely worth it to go non-AR route for pistol caliber. I shot the new B&T once and it was the softest shooting subgun, especially for its size, I've ever encountered. The MPX, MP5, Skorpion, all soft shooters. Crap using heavy buffers or bolts slamming around for blow back, like AR platforms, Uzis, Keltec Sub2000s, all smacked me around pretty badly.

Not necessarily disparaging the concept of the pistol caliber carbine, just .300 fits the roles I need better, but at the expense of a longer operating system (buffer tube, bolt carrier group, buffer spring and assembly) and higher ammo cost (somewhat negated by handloading).

 

[Disposable Heart]

I've had no problems with my PSA 9 Glock models. Had a 16" version that I put over 1500 trouble free rounds through it. Sold it and got the 8" version pictured on page 3. Over 500 trouble free rounds through it so far.

I could have had a bad one, but the one I did have broke extractors, even after adjusting buffer weight and ammo type. Not disparaging the gun, it just didn't fit my role.

Good info on the PSA AR9. I briefly handled a 2nd gen one at the NRAAM.

I'm interested in a Pistol Caliber AR or proprietary platform such as an MPX, and saw that the PSA AR9 was one of the cheapest, but looks like that comes at a price based on your info. Wonder if the Windham Weaponry or the Freedom Ordnance might improve upon those cons of the PSA, or if not, if it is just worth it to head down the MPX or Scorpion routes?

I think for the price, PSA has really nailed it down for the market. I have no direct experience with Windham but the Freedom I fired was meh for the price. You can tweak and get a metal mag catch for the PSA and have an almost identical gun. Even against the Keltec folding gun, for what people ask for them in price and for all its many negatives, the PSA AR9 is still a good route.

 

[bobjones223]

Good info on the PSA AR9. I briefly handled a 2nd gen one at the NRAAM.

I'm interested in a Pistol Caliber AR or proprietary platform such as an MPX, and saw that the PSA AR9 was one of the cheapest, but looks like that comes at a price based on your info. Wonder if the Windham Weaponry or the Freedom Ordnance might improve upon those cons of the PSA, or if not, if it is just worth it to head down the MPX or Scorpion routes?

I had a PSA AR9 Glock set up and ended up getting ride of it. I didn't like the fact that it didn't have a LRHO. So I went with a standard lower, mag block, and Colt style mags.

Ended up having the same amount of money in the set up as the PSA, had a LRHO, and could always use the lower for another caliber by just removing the block.

I am not saying that what I did was better than the PSA AR9, just saying that is what made sense for me.

I have never had a single failure with the system and LOVE IT!

As I side note I don't own any Glocks so I didn't have to worry about being able to share mags.

The other thing I liked about the Colt mags was you could load them like any other AR/AK mag. You didn't have to push down the last round and slide in the new one. You just pushed them all straight down.

 

[Areoflyer09]

Was kind of figuring that may be the case as I was typing that. I'm just starting to research. I assume the AR9's are a blow back setup?

I may take you up on that at some point.

How difficult or easy is the MPX to field strip for regular cleaning, etc?

It uses the push pins just like an AR. Pop the back one and tilt the upper forward.

Sadly I don’t get to play with mine nearly enough to be able to know how it is to clean if it’s really dirty.

 

[WebSnyper]

Thanks guys, lots of great info.

 

[WebSnyper]

It uses the push pins just like an AR. Pop the back one and tilt the upper forward.

Sadly I don’t get to play with mine nearly enough to be able to know how it is to clean if it’s really dirty.

Do you have a Gen 1 or 2? Sounded like from speaking very briefly to a Sig rep at NRAAM, he said the general difference was sizing for additional calibers in the Gen 2's. Is that correct?

Edit: I'm checking out this video here shortly on the Gen 1 vs 2: https://www.realgunreviews.com/sig-mpx-faq-video-analysis/

What barrel length, etc do you have?

 

[Areoflyer09]

Do you have a Gen 1 or 2? Sounded like from speaking very briefly to a Sig rep at NRAAM, he said the general difference was sizing for additional calibers in the Gen 2's. Is that correct?

Edit: I'm checking out this video here shortly on the Gen 1 vs 2: https://www.realgunreviews.com/sig-mpx-faq-video-analysis/

What barrel length, etc do you have?

Mine is a Gen 2 Carbine, I wanted the actual stock not a brace. I’ve not seen of any addition calibers, but I recall hearing that it was possible.

Edit: it’s a 14.5” barrel with a pinned 1.5” flash hider thing.

 

[hpclayto]

So do all receivers for glock mags not hold open on the last round?

 

[Cameramonkey]

So do all receivers for glock mags not hold open on the last round?

I have one that does. its not 100% reliable (weak mag springs cause it to fail)

https://www.joeboboutfitters.com/Spartan-9MM-45ACP-Billet-AR15-Upper-Receiver-w-LR-p/jb-9-lrbho.htm

 

[WebSnyper]

So do all receivers for glock mags not hold open on the last round?

At NRAAM PSA and Windham seemed to be touting that as a great new feature of their updated models, etc. I noticed several versions I looked at on the PSA site indicated the model did not have it, but I have not looked at all of them.

 

[WebSnyper]

Mine is a Gen 2 Carbine, I wanted the actual stock not a brace. I’ve not seen of any addition calibers, but I recall hearing that it was possible.

Edit: it’s a 14.5” barrel with a pinned 1.5” flash hider thing.

I don't even see an 8" MPX pistol on the Sig website currently. Seems all the pistol versions on the site have very short barrels. Not sure if I am navigating incorrectly or what. I think, though I need to shoot one that I'd want a pistol with a brace, but not a super short barrel, if I went the MPX path.