Looking for advice on a AR-40 upper.

[Nclear79]

Several years ago I had come across a deal for Winchester Ranger 165gr JHP 40 S&W. Fast forward today I own one 40 S&W pistol and have around 1,500 rounds of JHP.

I have been trying to sell it without any luck so my new idea is to get a 40 upper. I'd like to go with a pistol upper around the 10 inch to 12 inch.

Anyone have experience with the 40 in an AR? Thanks!

 

[Txhillbilly]

I don't have any interest in a 40 S&W AR, but do have a Ruger PC Carbine and a Kel-Tec Sub 2k in 40 S&W that I really like to shoot along with the five pistol's that I have in the same cartridge. The carbine's are even more fun to shoot with my sub-sonic loads with suppressor's.

 

[W.E.G.]

If you just want to burn up that ammo, find a pistol competition event.

You can burn through 1500 rounds shooting pistol in no time.

That way you will get some trigger time with your pistol, and some pistol training, and you won't be stuck with an oddball rifle in the form of yet another gun that you'll never shoot after the ammo is burned up.

 

[Ohen Cepel]

Mech Tech may make an upper for your pistol. Worth a look at least.

MechTech Systems | Pistol Carbine Conversion 1911 Glock XDM

 

[Demi-human]

yet another gun that you'll never shoot after the ammo is burned up.

Or worse yet. Become even more attached to the cartridge.
Then, as its popularity wanes even further, one will be stuck searching the internet for ammo again. As it’s scarcity increases, roving from LGS to LGS looking through back rooms and old stock will be the norm. Peddeling yard sale items to afford old fat magazines, while fellow shooters gasp at the excessive blast from such a mundane pistol. Then they’ll marvel in disbelief as an AR in the same caliber is produced, wondering why it would be a benefit to share that ammunition.

Don’t be an outcast, it will sell.


Whoa. Hold it. Did I just recommend some to not buy a firearm? Somebody slap me! I must be broken!
Yuck, maybe stress.
Okay, back in the game.

Yes! You should get another AR! And everyone should have a carbine and pistol, or pistol and pistol , combination with ammunition commonality.

Here is another place that that sells AR rifles and uppers.
https://www.newfrontierarmory.com/p...-10-upper-receivers/ar-45-10-complete-uppers/

And another.
https://moriartiarmaments.com/ar-40-.40-sw/

Whew, that was close!

 

[BigBlue 94]

JoeBobs Outfitters sells 40 ar stuff. I just got a shipment of stuff from them for a 10mm AR. New Frontier is the brand of lower i got. Seems like a quality piece for the price. Same with the barrel.

The good news is that you can easily swap the 40 barrel out for a 9mm pretty easy and the 9mm glock compatible lowers are also compatible with 40.

The 40 may be a dying caliber but ammo is everywhere. And lets be honest, it isnt anywhere near the rarity of say 22 savage HP, 22 Jet, 256 WM or 32NAA just to name a few. The 40 will be around for a long while.

 

[wesmonster]

One thing you’ll find out fast is that building or buying a 9mm AR upper is WAY cheaper than any other caliber.
There just aren’t as many options beyond 9mm.
Macon Armory makes some nice uppers, I’ve shot their 10mm upper and it was impressive. I’d love to have one in .45 but I went cheap and bought a Hi Point 4595. Very good for the money.
I also have a Ruger Charger 9mm, and the rifle version of that comes in .40.
If you go with a Kel Tec Sub2K you can have it in .40 and the multi caliber version has an option for S&W mags.
Rock River Arms also has a nice .40 upper and they make their own steel mags like the Colt/ UZI 9mm mags.
Do you already have an AR lower that takes Glock mags? If not, you’ll be looking at a magwell adaptor as well...

 

[BigBlue 94]

Buffer weight also plays a big role. Usually any blowback AR needs a buffer 2 to 3 times heavier than a standard CAR buffer. Too light of buffer and the action will "unlock" too quickly.

I ended up with about 1000 bucks in my 10mm.

 

[Heir Kommt Die Sonne]

Then, as its popularity wanes even further, one will be stuck searching the internet for ammo again. As it’s scarcity increases, roving from LGS to LGS looking through back rooms and old stock will be the norm. Peddeling yard sale items to afford old fat magazines, while fellow shooters gasp at the excessive blast from such a mundane pistol. Then they’ll marvel in disbelief as an AR in the same caliber is produced, wondering why it would be a benefit to share that ammunition.

Oh trust me, I've already gone through 1 of these things. People looking at me weird when I handle a nice 9mm and I say 'wish they made them in .40"

It's not that I "like" the caliber but it's easier to reload for than .357, so there's that. And a bigger bullet than 9mm? There we go.

 

[derek45]

USPSA/IPSC Limited Division is
major power factor
iron sights
no recoil comp.

40S&W is perfect for this, and USPSA is a blast.

 

[Bfh_auto]

Oh trust me, I've already gone through 1 of these things. People looking at me weird when I handle a nice 9mm and I say 'wish they made them in .40"

It's not that I "like" the caliber but it's easier to reload for than .357, so there's that. And a bigger bullet than 9mm? There we go.

Funny thing is cheap 40 ammo kills wild hogs better than a person would expect.
I think the OP should get an AR upper. It will double as a perfect home defense weapon.
Does the OP realize a pistol upper on a rifle lower is an SBR though?

 

[Nclear79]

Funny thing is cheap 40 ammo kills wild hogs better than a person would expect.
I think the OP should get an AR upper. It will double as a perfect home defense weapon.
Does the OP realize a pistol upper on a rifle lower is an SBR though?

Not when the lower is registered as "Other" I can make it a pistol or rifle.

 

[brass shower]

@Nclear79 I recently built a .40 S&W upper with a New Frontier Armory Glock mag lower and matching last round bolt hold open upper set. I used a Faxon 10” barrel.

Hand cycling the rounds fed fine no problem but I had some troubleshooting to do right off the bat when I took it to the range.

I initially used a KAK heavy PCC buffer, but the 10 oz weight was too heavy to cycle right with the 165 gr @ 1000 fps loads I started with. I backed the weight down to 8 oz which seems to cycle standard and hotter loads best. The other issue I ran into was feeding. Pointed bullets fed fine but any kind of flat point wouldn’t feed reliably with any magazine I tried when firing. The flat point would get caught on the face of the breech. I did some research on feed ramps and found one made by taccom3gun.com for $20. Doing some more research I found the ramp was too narrow for proper fit on my upper so Instead I bought a large 0.2” thick washer from the hardware store and using my grinder and dremel I shamelessly copied the design with a slight variation on the ramp design. It now runs everything I feed it. If I was going to do it again I’d get a barrel with the feed ramp already machined into the breech and save a lot of time.

 

[brass shower]

So far this is the only place I’ve found that offers ramped .40 AR barrels: https://shootinginnovationsllc.com/products/40sw-ramped-pcc-barrel

Note that these ramped barrels and the feed ramp I made won’t work with all Glock mag lowers. I tried fitting my completed upper with a Foxtrot Mike FM9 lower but due to the placement of the LRBHO catch on the lower the ramp interferes with assembly. A barrel with an integrated extended feed ramp will also not work on the FM9 due to the LRBHO unless the ramp is relieved to allow fitment.

 

[12Bravo20]

Rock River Arms also has a nice .40 upper and they make their own steel mags like the Colt/ UZI 9mm mags.

Rock River has not offered a 40 cal upper or magazines in a few years. And nothing is on their website for .40 and hasn't for some time.

 

[wesmonster]

Ah, guess they stopped selling when .40 waned in popularity. Too bad, RRA spent a lot of time on those mags, but that's the risk of proprietary stuff.
Now in .45 I think Macon Armory still has a combo kit .45 upper with Uzi style .45 mags and an adaptor.
Not sure if they offer a .40/10mm version

 

[12Bravo20]

Macon Armory does make a direct impingement 10mm upper but no 40 uppers. The 10mm uppers are on backorder though.

https://maconarmory.com/product/10mm-upper-receiver-group-di/