changing over to 9mm, is it really 'that easy'?

Jayne

Jayne

Just here for the memes
Charter Member
Supporting Member
Multi-Factor Enabled
Joined
Dec 16, 2016
Messages
8,028
Location
Unincorporated Wake County
Rating - 100%
34   0   0
Take a standard PSA 16" AR in 556 with a larue tigger (I think), replace the upper with a PSA 16" 9mm upper, stuff a endomag converted pmag in the mag well, chamber a round and go?

No buffer changes? No spring changes? No fiddling?

Won't destroy the fire control group?

Seems.... too easy.
 
Purely speculation cause I don't have a clue, but wouldn't the bolt face / extractor be different?
 
  • Like
Reactions: Tim
definitely need a 9mm specific BCG.

Almost certainly a heavier buffer/spring. My 9mm buffer I think is close to 9oz.
www.primaryarms.com

Home

DetailsThe Angstadt Arms Medium Weight Buffer Kit comes with an extra heavy buffer to help reduce recoil by slowing down the bolt during the cycling process. The buffer weighs 8 ounces and is constructed from steel with a Manganese Phosphate finish. The additional weight is also great for use...
www.primaryarms.com

Some AR triggers don't like the 9mm bolt. I'm running a GI trigger in mine without any problems.
 
Last edited:
Definitely need a new buffer, a heavier bolt and a stronger buffer spring.
 
If he's swapping uppers, he's swapping bolts too...

For the record I have used my SBR lower with an LWCR ultra compact stock/buffer setup and it worked fine with Endo mags and a Foxtrot Mike upper.
 
It’s been my personal experience to build a dedicated 9mm blaster and not try to multi-purpose other calibers/blasters. Pretty easy to do a 300 BO swap or a 22 LR conversion, but every 9 AR I tried to “adapt” just had one issue after another…
YMMV
 
The direct blowback of a 9mm is going to be pretty aggressive and you need to keep the bolt velocity nice and low so you don't have issues there with the unlocking.

Like other have said, bcg, obviously, but also a 9mm specific buffer which is going to be nice and heavy, and maybe an increased power recoil spring.
 
Meh, it can make sense to buy a dedicated lower for it. You can get a complete lower either assembled or whole for less than $120-150. I got shipped a 9mm barrel from PSA once by mistake when I ordered a 300 Blk barrel and it was educational. The bolt is definitely different, there was no star chamber and its a straight blow-back.

I would get a separate lower. I would probably just set it up with the right buffer/spring and let it eat compared to forgetting the springs and possible causing malfunctions going back and forth between rifle and pistol rounds. I know there are several magazine blocks available too, I would check the compatibility of your bolt and see if it can run any mag or if it will be best to use the ubiquitous Glock or Colt mags. Glock is practical, but there is something very 90's tacticool about a 9mm AR with the colt mags
 
If you go with the CMMG RDB 9mm upper, sharing lowers is literally a two pin affair.
 
Jayne said:
So what I'm hearing is... just buy the complete rifle.
Click to expand...
I think you would be happier with a glock or colt pattern lower.
I have several of all types. Use the colt pinned, drop in, one PC and pinned 2 PC, glock and colt 9mm only.

Find a lower and build spikes is good to go. CMMG for colt also.

As for buffers it takes a little trial-and-error. Had some that run normal carbine, h2 and h3 another that is 9oz to 11oz if I recall.
Run the spacer standard buffers and also 9mm extended buffers.
 
Jayne said:
So what I'm hearing is... just buy the complete rifle.
Click to expand...
What kind of magazine do you want to run? I know you mentioned endomags. They work, but they have a draw back. The ejector is on the magazine. If you pull your magazine then cycle your bolt it might not be unloaded. If the 9mm round hangs on to the extractor it could get rechambered.
I went with Beretta magazines to match my pistol. They make 30 round magazines for the CX4 that also fit the 92. I use a Stern Defense adapter in the mag well. But Glock mags and M&P mag adapters are also out there. The thing with adapter solutions is the magazine release button is relocated to the bottom is the trigger guard...so muscle memory kind of gets you when you start smashing the dead mag release.

So yeah, maybe buy a dedicated rifle with all the buttons and ejectors where you expect them to be.

20230607_153620.jpg
 
Last edited:
My buddy put a 9mm upper (PSA) with 9mm bcg on my milspec AR lower (carbine buffer) a couple endomags and it mostly worked. I think out of a few hundred rounds it may have malfunctioned once or twice. Probably buffer related?

As @Timfoilhat mentioned, the ejector on the actual mag weirded me out enough that I would avoid that setup myself.
 
Last edited:
If I were to build a pcc around a PSA upper, I'd personally look into the lower they make that uses scorpion mags.

Cheap, reliable, and abundant mags purpose built for pcc/smg use seems like a huge plus to me.
 
Cole_McD said:
If I were to build a pcc around a PSA upper, I'd personally look into the lower they make that uses scorpion mags.

Cheap, reliable, and abundant mags purpose built for pcc/smg use seems like a huge plus to me.
Click to expand...
Thats what I would do. Then again, I don't have piles of glock mags like some folks around here.
 
@Jayne you are most likely heavily invested with Glock Mags, since you shoot them in competitions. My suggestion is get a Glock mag dedicated lower. Endomags have proprietary parts that maybe difficult to find if they break. Glock mags and parts are a dime a dozen.
 
Average Joe said:
@Jayne you are most likely heavily invested with Glock Mags, since you shoot them in competitions. My suggestion is get a Glock mag dedicated lower. Endomags have proprietary parts that maybe difficult to find if they break. Glock mags and parts are a dime a dozen.
Click to expand...

PSA has an entire rifle setup that uses glock mags for under $700. That's likely the route I take if I want to go down this path.
 
Weren’t folks doing this 6 or 7 years ago having issues breaking off bolt catches? I’ve forgotten the details, maybe solved by extra heavy buffer?
 
New Bolt, New Buffer, have at it.
And if you got a ton of Glock mags your GTG..
Not a fan of Glocks so only 2 mags here.

went with a "Colt Patterned" Lower, Toolcraft 9mm Bolt v2, Macon Armory
Extended Dead Blow Buffer, and one of his guarantee to feed barrels, Colt
mags / ASC Colt Pattern mags, no issues. Rudy (Macon Amory) does great
work, stand up guy and company.

-Snoopz
 
GymB said:
Weren’t folks doing this 6 or 7 years ago having issues breaking off bolt catches? I’ve forgotten the details, maybe solved by extra heavy buffer?
Click to expand...
Most the broke bolt catches are from overtravel of the bolt being shorter.
Use a longer or extended buffer or the spacer and most cases that ends the broke bolt catch.
That was a thing with the colt 9mm. Mine broke several at $50 a pop you find out what is causing it. But that was in 1997 99 range.
 
Last edited:
I've been considering the same. Good info here. I've owned a bunch of PCC's. Two fav's were the AR pattern Colt and Glock mag ones. I prefer the Glock one. Primary reason is, mags are easier to load and load into gun on closed bolt and don't tend to explode when dropped loaded onto my concrete driveway when they fall out of the rifle bag. I never did find all of that mag.
 
You must log in or register to reply here.
Back
Top Bottom