Beretta ARX design details and wear at 500 rounds.

General Firearms Other Semi-Automatic Rifles
1

I’ve had this rifle for about 6 weeks and have about 500 rounds through it without any real stoppages, except during a rifle match, when a round popped out of the top of a magazine on a bolt open reload.

Some things that might not be apparent from the pictures:
There is very little aluminum in the design. The picatinny rails, barrel support, and selector/safety are the only aluminum parts on the rifle. Everything else is either steel or plastic.
It’s bulky but light. The rifle is very deep from top to bottom but pretty narrow. Most of the space forward of the mag well is hollow plastic around the barrel, gas cylinder, and forward nose of the bolt carrier.

Rifle with stock folded with sling attached. Finding a way to mount the sling is kinda a pain. The built in sling mounting points are too narrow to work easily with 1” slings. My solution was to use paracord loops to attach to HK hooks. That also helps with noise, is flexible, and is easy to remove.


Rifle field stripped into 3 basic groups: upper receiver, lower receiver, and bolt carrier group.

Upper receiver strips down to the barrel and receiver body.

Receiver details: Internal rail cuts on receiver. The steel BCG runs on plastic.

Receiver from below. I have no clue how they molded all those details at one go.

Front of receiver/barrel support. The aluminum barrel support has 3 legs that locate it in the plastic upper and a steel insert with sprung fingers that actually contact the barrel at the gas block.

Barrel details:
Barrel extension.

Bottom of barrel extension with wear from the barrel latch is apparent.

Top of barrel extension. The dished out area is clearance for the bolt carrier control pin spring.

Detail of the moving gas cylinder and stationary piston. The two spring tabs retain the two caps.

View into the lower receiver from the top. Visible is the center tab that activates the bolt hold open, the to side pieces that actually hold the bolt open, the green plastic hammer body, the steel hammer, black plastic trigger/sear, disconnector, drop safety, and the take down plate/ejector selector.

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Bolt carrier assembly in take down position.

Bolt carrier assembly detail stripped to three main components: Recoil spring with guide rod, CH slot dust cover, and buffer. Bolt carrier with CH. Bolt.

Bolt carrier underside details showing CH in ready position, note control pin in down position.

Wear on nose of bolt carrier possibly due to heat.

Assembled bolt detail of top showing Cam/FP retaining pin and slots that control bolt rotation during travel.

Side view of assembled bolt.

Detail of bolt face showing dual extractors/ejectors.
Bolt stripped showing bolt body, firing pin with spring, Cam/FP retaining pin, and extractors/ejectors.

Bolt face stripped.

Stripped bolt side view.

Slots for extractor/ejector tabs.

Cam/FP retaining pin. The pin is symmetrical and can be inserted either way.

Extractor/ejector details.

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Weight of assembled bolt carrier (335g) and bolt (158g) giving a bolt to bolt carrier weight ratio of 2.1:1. This compares with a AR 15* ratio of 7.1:1* and AK ratio of 4.9:1.


*FA bolt carrier with standard carbine buffer.

Detail of control pin/bolt interaction.During stripping of the new cartridge from the magazine, the cam path in the bolt tries to turn the bolt as it encounters resistance. This premature turning action is prevented by the control pin, which sits in a slot on top of the bolt.

As the bolt approaches the barrel extension the control pin spring hits the barrel extension as the bolt contacts the end of the barrel. The lifting control pin allows the bolt to turn and lock in the barrel extension.

The bolt carrier comes to a stop against the barrel extension and the control pin spring allows it to return to the lower resting position.

H

4

Excellent post. Have you stripped down the trigger pack by chance?

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I haven’t gone there. I’m pretty sure I can get it back together but I want to see pics of how it’s done before I rip into it.

H

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Nice post. One small thing though, the front barrel guide is not ceramic it is aluminum.

Beretta has informed me that there is no ceramic anywhere in the ARX-100.

Beretta has also informed me to never attempt to remove the top picatinny rail, as the 4 screws are held on with an industrial strength red Loctite threadlocker and you will damage the upper receiver if you attempt to remove them without the factory support jigs. This doesn’t really have anything to do with your post but is more of just a warning to anyone who may try to attempt it.

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I think you’re right about the barrel support being aluminum. I just looked at it again and there are a couple nicks that look like aluminum under the anodize.

I’ll make the correction.

H

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I’ve had mine about as long and put a similar amount of rounds through it. I have been very impressed with the rifle so far. Being a lefty and not having spent brass hit me in arm has been a big coup.

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Chris

9

do they make these in SBR forms?

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Not factory made, extra barrels are available from Brownells for 450. Or you could obviously cut barrel that came with rifle. A couple of guys have done it on berettaforum. Still trying to get gas port sizes correct. I’m waiting to do my form one after they have theirs squared away.

Chris

11

Thanks for the detailed report. This is definitely next on my list. It had to grow on me, but after MAC’s report and now this, I think it’s a “gotta have.” Good stuff!

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I’m starting to feel the same, but the incompatibility with M3 pmags and a hard trigger still make me wonder. Plus it’s ugly haha but as a lefty I can see the advantages.

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I played with one at the NRA convention last year. The plastic housing scares me. I really worry about it’s long term durability. At least the SCAR’s upper receiver is aluminum. I think I’ll stick to the AR-15 and SCAR platforms, at least until HK gives us the 416A5 and 417A2 variants I want :smiley:

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Long term durability is a concern for me too. Break the stock hinge or the stock latch point on the right side of the upper and you’re looking at a new receiver.

OTOH, I can buy two ARXes for the price of one SCAR. Is one SCAR more durable than two ARXes? I dunno.

OTOOH, I can buy a ARX for $200 less than a SCAR barrel will run me. Spare ARX barrels are priced right at $500 from Brownells too.

TANSTAAFL as usual.

H

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yea but Brownells is so expensive.

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Yes you can buy an ARX, extra barrel, and a tax stamp for less than a Scar. I think i’ll get one eventually just to see though.

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I want one now. I suppose to make up for not being able to get a Beretta AR 70. It doesn’t feel as clunky as it looks and I have enough GI mags that pmag issues don’t bother me.

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That BCG is built like a tank.

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Do they make aftermarket ones for it yet?

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Good stuff. If I had a decent camera, I’d post what mine looks like at just over 2k, not much dirtier than yours at 500rds. I’ve pulled a Bore Snake through the barrel a couple times and wiped the bolt off on occasion, but I’ve never really cleaned it. As I’ve posted before, it works as designed… so far.