PSA Gen4 4" 9mm 5" Lightweight M-Lok Railed MOE SBA3 Pistol Kit

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PSA Gen4 4" 9mm 5" Lightweight M-Lok Railed MOE SBA3 Pistol Kit

In stock

Regular Price: $ 679.99

Special Price $ 429.99

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: 5165458272
UPC: 5165458272
MFR#: 5165458272
  • 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
  • Build Kit: 9mm MOE SBA3 Pistol Build Kit, Black

Add To:

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.

Build Kit: A high quality lower build kit with everything you need to assemble your AR-9 lower into a pistol. Features Mil-Spec Fire Control Group, Magpul Grip, Magpul Trigger Guard, and black oxide coated hammer and trigger springs. Also includes SB Tactical SBA3 Adjustable Pistol Brace, castle nut, latch plate, carbine buffer spring, 5 positioning mil-spec buffer tube, and 9mm buffer.

SKU: 5165458272
SKU 5165458272
Brand Palmetto State Armory
Daily Deal No
Daily Deal Expires No
Youtube Video No
Free Shipping? Yes
Free Shipping Qty Label No
Free Shipping Qty No
SKU: 5165458272

Questions and Answers

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Browse 22 questions Browse 22 questions and 13 answers
will a deal like this ever be offered but with an 8 or 10 inch barrel?
Aaron F on May 10, 2019
BEST ANSWER: Waiting for the same! My wife needs a new ar9.
What magazines are compatible with this bolt carrier group and upper?
Nicholas R on May 8, 2019
BEST ANSWER: Colt and glock style mags are compatible with all of psa’s 9mm uppers
What lower receiver would be for this GEN4 4" 9mm build kit?
James L on May 8, 2019
BEST ANSWER: Any standard or 9mm ar15 lower will work. However, with a standard lower you will need an adapter for 9mm mags.
Will this work with a standard mil spec lower and Endomag?
Randy J on May 10, 2019
BEST ANSWER: I'm using psa's 10.5 9mm upper with the endomag mounted on a polymer lower with psa's enhanced fire group and it functions well.
What is the diameter of the rail? I am looking to suppress and just need specs. Thanks!
Ben D on May 9, 2019
BEST ANSWER: Just called and they say most if not all rails are 1.35" inside diameter.
Does this upper have a last round hold open bolt?
Kenneth on May 13, 2019
BEST ANSWER: It depends on the lower receiver.
Can you replace the brace with a folding style brace?
Michael C on May 9, 2019
BEST ANSWER: LRBHO is a function of a system on the lower not the upper.
What do you need to complete this kit?
George E on May 10, 2019
BEST ANSWER: You’ll need a stripped 9mm glock or colt style lower receiver. You can also use a standard ar15 lower receiver, with endo mags or a magazine well adapter
Does this upper have the last round bolt hold open feature?
Nsbjp on May 21, 2019
BEST ANSWER: An upper can have LRBHO as well, though not many do.
Will this work with a Rock River lower for Colt magazines ???
Marty on May 22, 2019
Never threading your 9mm ar barrels 1/2x28? So many 9mm uppers I have to pass on.
Andrew M on May 12, 2019
Will this work with a 5.56 lower with a glock magazine adaptor?
Jim F on Jun 24, 2019
BEST ANSWER: Yes.. I use the stern defense adapter.
Will this setup work with a Law Tac folding device and is it legal to do so? Does this increase "length of pull" to much to meet requirements?
Doug B on May 15, 2019
BEST ANSWER: pretty sure it says it wont work on the law tactical website. something to do with the 9mm bolts are not compatible
Will this work with a glock 9 mm lower ?
Tony s on May 10, 2019
BEST ANSWER: Works with my lower with stern defense glock mag block.
When will this be available?!
Austin S on Jun 18, 2019
Has anyone been able to actually use M-Lok accessories with this upper? the Flash can partially blocks the mlok slot
mike g on May 30, 2019
Will this deal ever be offered with the 16 inch barrel?
Carl S on May 22, 2019
will this bolt trip an auto sear?
Chris N on May 16, 2019
Will a magpul angled fore grip or hand stop fit on this handguard?
Samuel M on May 15, 2019
Can it come with the 6” handgaurd?
Adam F on May 14, 2019
Would this work with Olympic arms K9M 9mm magazines in a mil-spec lower?
J C on May 10, 2019


4.4 / 5.0
8 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Got to Have it!
Paired it with a Spike lower; as cool as they come. Even cooler than my 300 BC pistol.
July 16, 2019
2 months ago
No brainer if you want a starter AR9.
Great deal, I have ran 500+ steel rounds with no issue. Changed the charging handle, added an optic and it became my new favorite trunk gun. Great size and weight balance.
User submitted image
Added Jul 11, 2019
July 11, 2019
2 months ago
Great AR9 Pistol platform
Love the SBA-3 and this 4" barrel upper combo. Added a Sig Sauer Romeo 5 after about a month of shooting with Magpul pop up sights. Now, this is my primary home defense gun. Had to try some different Buffer's due to hang ups after 4-5 rounds. Ended up with a Spikes 7.4oz based on feedback from AR9 forums. Built a twin to this and didn't have the buffer weight issue..stayed with the stock Buffer that came with the SBA-3. Now have several hundred 115gr and 124gr rounds through them, all good.
July 10, 2019
2 months ago
Worked flawlessly. Pleased with purchase
June 24, 2019
2 months ago
Looks good but wears quick
It looks great and feels awesome, but it seems like there is a lot of bolt wear overall. When firing black specs come off and I have to clean them off
June 18, 2019
2 months ago
Fun pistol
Pistol kit went together just fine. Gun runs well. Only drawback is with the 4 inch barrel and the big flash can the M lock slots are useless. Not enough clearance to attach . Same problem w/quick detach sling swivel hole. The barrel stops the swivel from inserting all the way.
June 12, 2019
2 months ago
my new favorite pistol
assembled onto a spike's tactical ARG st9g 9mm lower with LRBHO and it runs perfectly. fired almost 300 rounds threw it
June 6, 2019
2 months ago
Not too bad if you have some basic gunsmithing skills.
Got a good deal on this to build with my standard .223/5.56 stripped lower. Make sure if you are using endomag pmag adapters to use this kit with a standard .223/5.56 lower that you have the mag catch/release hardware, because its not included with this kit.
After I received the kit and got everything assembled, I went to test fire it, and it wouldn't cycle a round into the chamber without jamming hard and damaging the case of the ammunition. Also there were minor clearance issues between the bolt carrier and upper receiver that caused the bcg to drag and resist going all the way forward.
After closer inspection, I realized there was poor/incomplete machining at the top of the feed ramp of the barrel. There was a ridge that wouldn't allow the ammunition to enter the chamber without the casing catching on that ridge and jamming. A few minutes with some 120, 400 and 800 grit to remove the ridge and polish the feed ramp did the trick. After inspection of the bolt, I could see where it had been dragging against the upper. Again, a few minutes with 400 and 800 grit did the trick to get the bcg to cycle smoothly.
Got it roughly sighted in with a cheap red dot sight and it now functions 100% after about 50 rounds.
May 23, 2019
2 months ago
Response from Palmetto State Armory
We do apologize for that. Please contact Customer Service so we may resolve this issue.
May 24, 2019
Casey S

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