PSA Gen4 4" 9mm 5" Lightweight M-Lok Railed Upper - With BCG & CH - 5165450004

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PSA Gen4 4" 9mm 5" Lightweight M-Lok Railed Upper - With BCG & CH - 5165450004

In stock

Special Price $ 299.99

Regular Price: $ 449.99

Quick Overview

free shipping Free Shipping applies to this item only and not the entire order.

It is the customer's responsibility to be aware of all applicable laws and regulations regarding the purchase and ownership of uppers with a barrel length of less than 16". Federal NFA regulations are applicable to this item.

WARNING: This product can expose you to the chemical lead, which is known to the State of California to cause cancer and reproductive harm. For more information go to (CA Health and Safety Code Section 25249.6).

SKU: 5165450004
UPC: 5165450004
MFR#: 5165450004

Barrel Length: 4"
Barrel Profile: Heavy
Barrel Steel: Chrome Moly Vanadium 
Barrel Finish: Nitride 
Chrome Lining: No
Muzzle Thread: 1/2-36
Chamber: 9mm (9x19)
Twist Rate: 1 in 10"
Barrel Extension: 9mm, Blowback
Muzzle Device: PSA Fluted Flash Can
Receiver Material: 6061 Billet T6 Aluminum
Receiver Type: Slick Side 
Handguard Type: PSA 5" Lightweight M-lok Rail
Bolt Included: Yes 
Bolt Steel: 8620, Nitride / Heat Treated

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Barrel: 4" chrome moly vanadium steel barrel. Chambered in 9mm (9x19), with a 1/10 twist rate. The barrel is nitride treated for durability and finished off with a PSA 5" Lightweight M-Lok Rail, and a PSA Fluted Flash Can muzzle device.

Upper: Newly designed 6061 Billet T6 Aluminum slick side upper is hard coat anodized black for durability.  Featuring T-marks, these upper receivers are made for us right here in the USA.

Bolt Carrier GroupGen 4 Hybrid 9mm BCG.  Nitride treated 8620 steel bolt, with an enhanced firing pin and external 5.56 style extractor. The bolt carrier group is compatible with most aftermarket fire control groups. 

Flash Can: Palmetto State Armory's new fluted flash can. This is a solid 6061 aluminum device that is designed to direct muzzle gases and the muzzle flash forward. Threaded 1/2-36 for 9mm.  Black military-style hard anodizing.   THIS DEVICE IS NOT DESIGNED TO REDUCE RECOIL, MUZZLE RISE, OR FLASH SIGNATURE. This device is designed to direct gasses and noise forward away from the shooter and enhance the weapon's appearance.

SKU: 5165450004
SKU 5165450004
Brand Palmetto State Armory
Daily Deal No
Daily Deal Expires No
Unit Price N/A
Youtube Video No
Free Shipping? Yes
Free Shipping Qty Label No
Free Shipping Qty No
SKU: 5165450004

Questions and Answers

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Browse 61 questions Browse 61 questions and 72 answers
Does this work with standard lowers? FA bolt carrier? What mags?
Diesel R on Nov 2, 2018
BEST ANSWER: Need a 9mm Glock or Colt lower. It already comes with a blowback bolt carrier. Takes double stack Glock mags or Colt mags ( depending on which lower you get )
If i already have a 556 lower do I just need a magazine adapter?
Dbb1911 on Nov 5, 2018
BEST ANSWER: Yes, or the EndoMag 9MM by Mean Arms will work as well with standard P-Mags.
Does this need a dedicated pistol lower to build a pistol in Michigan?
Steve C on Nov 2, 2018
BEST ANSWER: Yes It needs a PSA 9mm Lower reciever.
Does this upper facilitate a "last round hold open" function or is that a feature of the lower?
Eric on Nov 3, 2018
BEST ANSWER: Last round hold open is a feature incorporated into a lower receiver.
what is the rail inside diameter?
m h on Nov 9, 2018
BEST ANSWER: The inside diameter of the rail is ~1.35"
Is there a certain 9mm ammo grain to run through this upper?
Michael R on Nov 28, 2018
Will this upper function with a New Frontier Armory C5 lower? It feeds from MP5 magazines.
David R on Dec 26, 2018
BEST ANSWER: No. That lower has what I call a magazine stop (that prevents the MP5 mag from going in further) that hits the bolt on this upper.
Is this compatible with law tactical folder and fostech echo triggers?
daxh1 on Dec 23, 2018
BEST ANSWER: Yes . Any standard AR upper will work with the law tactical..
What is the inside diameter of the handguard? I'm wanting to put a suppressor on this.
Mason on Nov 23, 2018
BEST ANSWER: .135, most suppressors will fit.
Can the can be removed for addition of a suppressor?
Dan S on Nov 6, 2018
BEST ANSWER: Yes it can. 1/2-36 threads on this barrel.
What is the overall length of upper or length of barrel plus flash can info would be helpful?
Josh B on Nov 5, 2018
will this bolt work with a gen 2 fostec trigger?
hondafig on Feb 7, 2019
Is the BCG compatible with a LAW tactical extension?
Matt H on Jan 28, 2019
if i put an 11" can on it, would it then be league to put it in a rifle lower ?
paul s on Nov 3, 2018
BEST ANSWER: it depends.
assuming this has a legal length of 4 inches and you attach an 11 inch can to it you would still need another inch to meet the minimum 16 inch requirement.
4+11=15 +1 =16 but this would only count if all devices are welded together. if you can take it apart and at any point the entire configuration is less than 16 it cannot be a standard rifle barrel.

so if you had this and an 11 in can and a 1inch spacer or muzzle brake between them it could be 16 inches overall and still not be legal.
it would require welding the barrel to the muzzlebrake to the can to count as a 16 in barrel.
I have a ad9 conversation and it requires a bolt with glock cut. Does the upper's bolt have the glock cut in it?
Jason L on Dec 26, 2018
Does anyone know the Inside Diameter of the handguard? Or, at least the OD of the flash can?
Adam S on Nov 4, 2018
BEST ANSWER: 1.2 inches is the outside diameter of the can
Do these uppers come with ramped barrels?
Hank L on Feb 4, 2019
What is inside diameter of handguard?
Dave H on Jan 2, 2019
Is this BCG ramped ?
Jziggyp on Jan 25, 2019
I love the upper but am having trouble with rounds snagging and jamming as they enter the barrel. They are getting caught on the ramp entering the barrell. Any one else have this problem or know of a fix?
Dennis A on Jul 7, 2019
BEST ANSWER: Please e-mail, or call and and we can get your firearm taken care of. It is back be a Lifetime Warranty.
this lower work w/ this upper PSA Gen4 ?
carlitod on Apr 22, 2019
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PSA PA-9 Billet Glock®-style MOE EPT Adjustable brace Lower - 5165450178
PSA PA-9 Billet Glock®-style MOE EPT Adjustable brace Lower - 5165450178
BEST ANSWER: It should work ! I set mine on a Colt .223 lower w/ magwell adaptor using 9mm colt mags .Ran flawlessly !!! The chamber is conical so no feed ramp is needed, so feeds straight in.I would get a slightly longer BBL. 6,7 or 8"so u can use a supressor because end of threads are inside handguard, a pain !
Is there a spacific Glock mag adaptor I need for the standard lower or will any mag adapter work with this upper ?
Trent on Dec 20, 2018
BEST ANSWER: I am running the Mean Arms mag adapter
Will this drop directly in my ar15 lower with stern defense mag conversion?
Tandh on May 4, 2019
BEST ANSWER: It was compatible with the stern defense conversion but I was very disappointed with it. It was only compatible with new Glock magazines that have mag catches on both sides. It also would not drop mags freely you had to remove them because the tolerances weren’t very good.

I have since found a product from a company called mean arms. It is a 9 mm P mag conversion kit. I bought the three magazine conversion kit I’ve run all of them through that upper on a Palmeadow lower. A few of them we’re holding the last round but after a few mag dumps that cleared up.

Hope that helps
Www. Meanarms .com
Can I place this upper on another PSA 5.56 pistol lower and it would work and cycle fine? Understandably would have to get ENDO mag conversion kits for magazines.
Michael P on May 3, 2019
BEST ANSWER: You’ll have to change it to a 9 mm buffer and is likely a heavier spring, AR10 type. You may also need a spacer or a few quarters in the bottom of your buffer tube to make sure you don’t tear up your boat couch. Your hammer may not work if it isn’t rounded on the forward edge.
Has anyone installed any kind of foregrip/hand stop on this? Curious if there's enough space.
Matt D on Mar 9, 2019
BEST ANSWER: I added a Magpul M-lok angled foregrip. I could only use one M-lok nut & bolt. Tightened down well with blue lock tite. Seems to be holding well after shooting the AR9 on the range.
Will this work on a C-5 lower platform?
Terry S on Feb 15, 2019
BEST ANSWER: If you are referring to New Frontier Armory’s C-5 lower receiver, the answer is no. The NFA C-5 lower has a magazine limiter that sticks high above the receiver that would hit the bolt on this upper. If a slot is machined into the bolt to clear the magazine limiter, that might work, but I have not tried it.
Is the can removable for other flash hinders or mussel breaks?
Andy L on Feb 11, 2019
BEST ANSWER: Yes. Its a threaded barrel so the can is removable. I had to disassemble mine for hyro-dip.
If I put this on a standard ar15 pistol lower, with and Endo mag for the pmag, what else would I need to make it function properly, and would it cause damage to the lower?
Paul I on Jan 15, 2019
BEST ANSWER: Well, a standard AR buffer won't work, so you'll need one of those. Other than that your answer depends on what you consider 'functioning properly'. There are lots of different routes you could go, but if you want proper function, you should ditch the ar15 lower and get yourself an ar9 lower that runs colt mags. Since that particular platform has been around a while, LRBHO is built in and the feed ramp is built in.
Is the Dolos kit compatible with this?
Kevin D on Jul 10, 2019
BEST ANSWER: Haven't tried it, but since the upper uses a milspec barrel nut, I would say yes. You will need to research if your specific handguard is compatible with this barrel nut setup.
What are the parts I would need to complete the build using the Betsy Ross 9mm lower I purchased Friday?
Will P on Jul 7, 2019
BEST ANSWER: You will need a lowers parts kit , or drop in trigger, a pistol brace or pistol tube , and a red dot or flip up sites. And watch some utube videos.


4.7 / 5.0
39 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
This company is great to work with. I always receive updates on orders and have never had an issue with anything
I have built 2 ar9 pistols with this upper. This is a high quality product and will buy more for sure.
User submitted image
Added Jul 21, 2019
July 21, 2019
1 month ago
NOT A Good Fit
I am disappointed in this product. The fit with a lower needed to be machined to fit and the lrho had to be filed to fit correctly just to close the front and rear pins. These were. ot due to the casting, as I have prints for fit and finish.
July 9, 2019
2 months ago
Gen4 9mm upper
Runs great, my only hang up is I wish it had a dust cover like the original colts. Other than that is great.
July 4, 2019
2 months ago
Excellent unit. I highly recommend Palmetto State Armory.
User submitted image
Added Jun 30, 2019
June 30, 2019
2 months ago
Awesome ran great looks good, no issuesl. Love my set up for two third less the price of some higher end 9mm pistols.
May 31, 2019
Ran great !!!no issues
May 22, 2019
7 months ago
You need this upper!
Upper is awesome. Paired with a Black Dirt Rifleworks 9mm Buffer and no issues. Shot 200 rounds of multiple ammo types and reloads without issue. My only wish is that there were enough slots to add a m-lok handstop. I also was impressed that it was shipped the next day after my order.
User submitted image
Added May 8, 2019
May 8, 2019
Great Upper!
Bought this 4" upper to pair with a PSA 9mm complete lower and they both match up perfect together. Fit and finish are top notch and have run over 250 flawless rounds through it so far. Out of all my pistol builds this is by far my favorite!
User submitted image
User submitted image
April 16, 2019
8 months ago
I like my upper 9 mm . Only thing I didn't know if you buy a short Barrel, you have to buy a pistol lower to be legal.
User submitted image
Added Apr 14, 2019
April 14, 2019
5 months ago
Great 9mm!
Great pistol, shoots great. Only reason I gave it four stars is due to having to order a different handrail to fit my suppressor.
Need an after market handrail. The hand rail it comes with doesn’t have clearance for a 1.3” can.
Need an after market handrail. The hand rail it comes with doesn’t have clearance for a 1.3” can.
April 12, 2019
5 months ago

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