AR carbine 9mm, 300blk, other?

Status
Not open for further replies.
WestKentucky

WestKentucky

Member
Joined
Feb 1, 2014
Messages
13,116
Location
Western Kentucky
I never grew particularly fond of 223/5.56 in over 15 years of owning one. I sold my last one yesterday, and don’t plan to jump back into that caliber. I have a lower and want an AR carbine as they are handy and fun, but I’m leaning towards a 9mm or a 300blk as I already stock and reload 9mm and stock .308 115gr bullets for 30 carbine. I also would consider 7.62x39 and a whole host of 20 caliber rounds, but they are a bit further away from what I think I want. I’m open to suggestions and comments. 10mm would be preferable but I haven’t seen one priced reasonably in quite a while. If I go 10mm I will likely just buy a complete gun rather than build up my 80% lower again.
 
I’m sure it goes without saying that your current lower (if made for AR15 mags) won’t work for a handgun cartridge like 9mm. If you plan on using your current lower for your build then .300 BO would be a good choice since you have .30 caliber bullets on hand.
 
I have .300 and 7.62x39 ARs because they're the easiest to run as alternate calibers. With the 7.62x39 I'm running caliber specific magazines. No need for that with the .300. If you don't have firearms and ammunition 7.62x39 already like I do the decision might weight towards the .300.

I've avoided a 9mm AR since it runs best in purpose built lowers and there are tons of 9mm carbines and "pistols" out there that will happily run 9mm. You can get the Ruger 9mm Charger, a CZ EVO, or something else. That said, I have a 9mm KT carbine using Glock mags as well as a G19 all comfortably fitted in an old compact laptop bag.
 
In my experience, a 9mm AR does run best on a dedicated lower. I have a Rock River LAR-9 upper that I ran on a standard lower with a Hahn block. I never could get it to stop jamming (FTF). Eventually, I bit the bullet and bought a dedicated RR 9mm lower. The gun has run like a top ever since.

On the plus side, I have an extra lower now. And I can't overstate how much fun it is to have a 9mm AR.
 
The biggest problem with AR's of any caliber is that they tend to be hungry. 300 BLK is a great round, but unless it is being ran suppressed, I really don't see the point. It seems 7.62x 39 is the cheapest and most available round about lately, even though it is still highly overpriced in the current market. I have never messed with a AR in this caliber myself. I have heard that they can have feeding issues due to factors regarding the optimum magazine shape for best feeding of that round (as in AK) vs the required magazine shape to fit in the AR lower.
 
My 9x19 AR just has never lit my fire. You get a bit of boost in velocity but not much.

If you reload, 300 Blackout would be a good choice. I shoot only supersonic in mine but you can add a suppressor if you want to deal with the paperwork.

I feel the 300 Blackout is a dandy home defense rifle.

I feel 7.62x39 is a waste of the AR’s accuracy potential.
 
It depends on your purpose. If we're talking just general defensive and rifle use, if I couldn't have 5.56 in an AR I would probably want a 7.62. I'm not really a fan of PCC's so I'd want a rifle caliber, and the 7.62 is cheap and readily available (normally). If you are thinking more of an AR platform rig you could take hunting I may lean more towards a 6.5 Grendel.
 
Lennyjoe said:
I’m sure it goes without saying that your current lower (if made for AR15 mags) won’t work for a handgun cartridge like 9mm.
Click to expand...

That isn't accurate. There are several ways to convert an AR lower, designed to shoot a large rifle round to shooting pistol rounds. Some are AR magazines with different springs and followers to fit PCC or they can be magwell adapters to accept something popular like Glock magazines.

https://cmmginc.com/product/adapter-magazine-9-ar-conversion-10-30rd/
https://getstern.com/products/magazine-adapters/
 
herrwalther said:
That isn't accurate. There are several ways to convert an AR lower, designed to shoot a large rifle round to shooting pistol rounds. Some are AR magazines with different springs and followers to fit PCC or they can be magwell adapters to accept something popular like Glock magazines.

https://cmmginc.com/product/adapter-magazine-9-ar-conversion-10-30rd/
https://getstern.com/products/magazine-adapters/
Click to expand...

I digress. If you want to do it “correctly “ you’d buy a pistol lower to accommodate your pistol upper. But, like others said, there’s always a way around it..
 
The 9MM AR is a lot of fun and cheap to feed, mine's a RRA with the load block that takes modded Uzi mags or Colt SMG mags (Or clones), runs 99.9%.

My 300 BLK is also a lot of fun, reasonable to feed, enough power to hunt with if shot placement is good.

I sold my 7.62X39 AR upper, because it was just a toy, it does give more power than the 300 BLK. I sold my AK too. No more 7.62X39.
 
I m running the 9mm CMMG RDB system with endomags.
Its built on a mil spec upper and lower. Running a mil spec carbine buffer and spring. The RDB system gives a milder recoil than the regular blowback system. I have had zero problems with mine. There are some reports about ejection issues. I think they have worked the problem out with a different ejection spring.
 

Attachments

  • 20200204_190012.jpg
    20200204_190012.jpg
    108.9 KB · Views: 10
My wife shot the 9mm carbine with red dot recently and she loved the fact that she could quickly and easily make accurate head shots on a silhouette plate out to 100 yards that she never would make with her Glock. She also likes the fact that it is so much more quiet. She sent her sister a picture of the carbine because the sister who also owns a Glock wants something quieter for home defense. The carbine would be perfect for her. Not much of a velocity increase over a pistol? How about ~1650fps with 115 +P+ loads? Or go the subsonic route with 147gr hollow points.

M
 
Last edited:
I finally bit the bullet and built an AR9 PPC. I used Aero Precision upper and lower receivers with Stern Defense bolt and mag adapter for SIG 320 mags. Mine works great, it is much more quite than a .223 AR, and it is dirt cheap to reload for. With the current ammo shortage, I use the AR9 for most of my practice.
 
Last edited:
My RRA dedicated 9mm carbine will destroy clay birds @ 100 yrds off a rest using my 147 gr RMR TMJ loads. The dot was moved to my AR 15 .22LR and a Vortex Strikefire II was added. I'm in the process of building an anti urban uprising load bearing rig in case of things going south. I already have M4 and 74 rigs kitted up and ready.

Bill IMG_1116.JPG
 
What do you want to do with the rifle ? Does it really matter ? :)

My next will be a 9mm. Mostly because I load 9mm now and have the supplies. It'll be a toy with a slight possibility of small game/varmint control.

-Jeff
 
The .300Blk offers a lot of utility and flexibility. For strictly supersonic loads, I think the 6.5Grendel or 6.8SPC might be better choices. Just depends on what you want to do with it.

I wanted a 9mm AR for years but I'm glad I waited. The CAR15 just seems so dated now. If I was going to do a pistol cartridge AR, it would be with a dedicated lower. Not an adapter that uses Uzi/Colt type mags. Not real nuts about Glock mags either. Glad there are better solutions available. Like the Scorpion.

CZ%20Scorpion%2003.jpg
 
tarosean said:
Is the extractor made of metal or plastic? Interesting work around for the 9mm issue.
Click to expand...

The extractor is metal. Search the CMMG RDB. Im getting ready to build another 9 mm AR. I will be using the CMMG RDB system again.
 
A good option is the Palmetto AR-V. It uses commonly found AR parts with the only proprietary parts being lower, upper and bolt. It utilizes scorpion patterned magazines which PSA has their own scorpion patterned magazines that are very well built and run flawless for $14 / magazine that holds 35 rounds.

https://palmettostatearmory.com/pa-9-pcc/ar-v.html

Again, I don’t know what needs you have for this new firearm which would help direct suggestions.
 
WestKentucky said:
I never grew particularly fond of 223/5.56 in over 15 years of owning one. I sold my last one yesterday, and don’t plan to jump back into that caliber. I have a lower and want an AR carbine as they are handy and fun, but I’m leaning towards a 9mm or a 300blk as I already stock and reload 9mm and stock .308 115gr bullets for 30 carbine. I also would consider 7.62x39 and a whole host of 20 caliber rounds, but they are a bit further away from what I think I want. I’m open to suggestions and comments. 10mm would be preferable but I haven’t seen one priced reasonably in quite a while. If I go 10mm I will likely just buy a complete gun rather than build up my 80% lower again.
Click to expand...
If 9mm is a contender, then other stuff like 6.5, 6.8, .350, .450, .458, beo, etc will probably be overkill, but I would throw the .350 and .450 in for giggles consideration. Personally, with primers being so hard to come by, a lack of ammo in general, and the contemplation of indoor use, stumbling across a VERY healthy local supply of shelf ammo stamped .300 aac swayed me to add an upper in such a chambering to the stable. It is niche for sure, but we have just enough use for it to justify it and the multithousands of rounds available help tip the scale for us. Your situation may differ enough that 9mm would be a better bet, only you can say for sure since we don't know what you're planning on doing with it.
 
I’ve yet to warm up to pistol caliber concept. I use a Mini 14 as my .223 and use it for critters off my front porch. I went with 300 bulk went I bought a PSA branded AR. I like shooting the Mini better but the AR is a great rifle. thumbnail-IMG-0264.jpg
 
horsey300 said:
If 9mm is a contender, then other stuff like 6.5, 6.8, .350, .450, .458, beo, etc will probably be overkill, but I would throw the .350 and .450 in for giggles consideration. Personally, with primers being so hard to come by, a lack of ammo in general, and the contemplation of indoor use, stumbling across a VERY healthy local supply of shelf ammo stamped .300 aac swayed me to add an upper in such a chambering to the stable. It is niche for sure, but we have just enough use for it to justify it and the multithousands of rounds available help tip the scale for us. Your situation may differ enough that 9mm would be a better bet, only you can say for sure since we don't know what you're planning on doing with it.
Click to expand...
General purpose for the gun is essentially a range toy. It may be employed as a short range deer hunting gun for the kids, which is why I’m not headed straight to .450bm. One daughter has fallen in love with my marlin 62 30 carbine which is adequate for short range. The other daughter likes my 6.8ar but it’s about 3 times as heavy as she can handle. I want light weight, lower recoil, but bigger bullet than 224 diameter. Things like 6arc would be great but I don’t want to drop a grand on a build that I have little use for. 9mm seems logical since I reload and have a pile of components already. Using beretta mags would be awesome but I expect Glock-mag blocks to be more easily sourced and more reliable. I also like the thought of a short stubby subcompact mag for hunting and a long aftermarket mag for range fun.
 
Status
Not open for further replies.

Similar threads

C
  • Locked
Sterling or AR for 9mm carbine...or other
2
Replies
25
Views
1K
cz85cmbt
C
D
  • Locked
Building an AR9
2
Replies
30
Views
889
DesertFox
DesertFox
bersaguy
  • Locked
M1 Carbine vs new pistol caliber carbines
2 3 4
Replies
77
Views
11K
JWF III
J
A
  • Locked
Olympic 10mm AR
Replies
21
Views
2K
Antihero
A
Zaydok Allen
  • Locked
KRISS 10mm Carbine
2
Replies
32
Views
4K
Zaydok Allen
Zaydok Allen
Back
Top