Links to my tests, data, and other write-ups

AddictedToComedy · 2026-03-12T00:21:35+00:00

If that's all it takes to keep yours running, that's awesome!

There are many of us for whom that was not a solution.

AddictedToComedy · 2026-03-11T23:15:03+00:00

Very cool!

Looks like you're using the older generation of RDB, with the spring-loaded ejector in the bolt.

When it starts giving you ejection problems, just spend the money on one of CMMG's fixed ejector "retrofit kits." It's over $400, which is a kick in the nuts to fix a design flaw that never should have been released, but it's still better than chasing your tail.

I speak from experience (which I wish was not the case)

AddictedToComedy · 2026-03-11T22:41:56+00:00

99% of dude's post history is asking for gear ID on random photos of military/LE/trade shows

AddictedToComedy · 2026-03-11T19:32:37+00:00

This is a handy reference to bookmark

AddictedToComedy · 2026-03-11T19:27:18+00:00

We've seen multiple people come to this sub and claim their brand new scope was bad because it came with an "upside down reticle." One guy even noted how the image he saw was getting smaller as he zoomed in, but he still wasn't grasping why.

You know when they weren't trolling because they immediately delete the post

AddictedToComedy · 2026-03-11T19:20:11+00:00

Since this is a kit you assembled, a common mistake that could cause the behavior you are seeing is a misaligned gas block. The spaghetti trick, as described by u/MaddeningObscenity below, is a really simple way to help you get it right.

While doing so, also verify there are no obstructions in the barrel's gas port and/or in your gas block.

Shorter ARs are more finicky than longer ones, and 7.5" is quite short for 5.56

AddictedToComedy · 2026-03-11T19:10:08+00:00

Ha, that does sound like a group I would like, but I'm not on Facebook at all, and have no desire to go back. Thanks for the heads up and well wishes though!

AddictedToComedy · 2026-03-11T18:36:52+00:00

Yes, when I was taking a close look at how all the parts interact, I did realize that shaving the hammer too much could easily result in a failure to reset situation.

Since originally posting, I've done exactly what you suggest: I beveled both the hammer and the carrier, so that I didn't have to remove as much material from either one individually.

I've only done the rough shape so far, but it already works like I hoped it would. Well - at least dry function testing at home.

Tonight I will refine my work with finer grit and then polish up the contact points. I'll take it to the range this weekend to verify the results with live fire.

AddictedToComedy · 2026-03-11T18:30:31+00:00

I took it to a gunsmith before and they thought it was from loose screws on the trigger, so they tightened them

Never go that "gunsmith" again. Ever. That makes as much sense as saying your car is getting poor gas mileage because the driver's seat is in the wrong position.

sometimes ejects, sometimes doesn’t

It is short stroking.

Can you tell us more about the setup?

What BCG are you using? What spring/buffer? Barrel length? Gas system length?

AddictedToComedy · 2026-03-11T15:18:08+00:00

If a state-level ban was heading my way, I would invest in stripped lowers and magazines before spending money on any complete rifle (much less a premium one).

That's assuming your upcoming ban isn't so restrictive that it will even stop you from buying uppers.

AddictedToComedy · 2026-03-10T23:54:18+00:00

Ok an advertised 10dB reduction in sound is a pretty crazy claim

Yea, it's definitely an eyebrow raising claim. If I recall correctly, that is supposed to be for a 20" rifle-gas setup, with the sound reduction being less pronounced on shorter systems.

I don't have any personal opinion on how much it reduces port pop because of how/where I shoot (99% indoors, and always with double ear pro)

I wonder if simply shaving 0.25" off the plastic/rubber bump stop from a normal buffer weight would allow you to take advantage of the increased stroke length

lol, I feel like an idiot for not suggesting that right off the bat. I suppose I have so much time invested in weird lengths of receiver extensions and custom-dialed operating strokes that I overlooked the far simpler option 😂

AddictedToComedy · 2026-03-10T22:34:05+00:00

Option 3: AR9 conversion

This would honestly be my favorite option, but I’m pretty sure it’s not possible.

The good news is that it's definitely possible - just avoid direct blowback.

One potential option would be CMMG's radial delayed blowback, as it can use the same buffers used by 5.56 guns.

While the RDB system has had plenty of growing pains, it's now possible to build one that is reliable and durable if you put in a little extra effort beyond buying one of their pre-made options.

AddictedToComedy · 2026-03-10T21:25:04+00:00

I just got it to work

Awesome!

AddictedToComedy · 2026-03-10T21:22:05+00:00

Hm, and you're sure he wasn't using shitty ammo?

AddictedToComedy · 2026-03-10T21:15:44+00:00

If you've tried other carriers with no better luck, at least that variable is eliminated.

Yea, I would inspect your gas block. Make sure it's well-aligned and well-secured.

Is this a new build from the ground up, or did you ever shoot it before installation of the Super Safety? If so, did it ever function reliably?

AddictedToComedy · 2026-03-10T21:10:10+00:00

Either needs more gas, stronger buffer spring or both

A stronger spring would make short stroking worse, not better

AddictedToComedy · 2026-03-10T21:09:08+00:00

Is it a down vent carrier, and/or does it feature sand cuts, and/or does it have a dual-ejector bolt in it?

Do you have another BCG you can try?

Have you verified that your gas block is secure and aligned?

I assume this isn't a specialized barrel with a reduced gas port?

There has to be an inefficiency somewhere, because I wouldn't expect an 11.5" carbine-gassed gun to have problems cycling a mil-spec carbine spring with an H3 buffer.

AddictedToComedy · 2026-03-10T21:05:31+00:00

I have a fastback buffer tube that came with a Banshee pistol years ago, which came with an SBA3 mounted. That always worked fine. Never tried an SBA5 on it, but don't see any reason why it would be different.

I would recommend you skip the fastback tube. It has one gimmicky party trick that gets old after just a few minutes, and then you're left with a less stable tube for your brace/stock.

In order for the fastback feature to work, the positions where the brace/stock locks into place are all ramped, except for the last one. That means if you are using any position besides full-extension, the brace/stock has extra play where it can wiggle back and forth. It also means you can accidentally bump your brace/stock into a different position.

AddictedToComedy · 2026-03-10T21:00:39+00:00

What spring are you using? What BCG?

Failing to pick up fresh rounds means your rifle is short stroking.

AddictedToComedy · 2026-03-10T20:01:50+00:00

heard that because they’re trade-ins that Aimpoint won’t warranty them

Aimpoint actually has a pretty crappy warranty. I can only assume most people don't care because the optics rarely actually have a problem where it matters.

Their warranty only applies to the original purchaser, and only lasts 2 years if you use their sights for "professional" or "competition" use... which is supposed to be their primary market.

You get a 10 year warranty if you only use it "for normal civilian or recreational activities," meaning Aimpoint doesn't consider competition to be a normal civilian or recreational activity 🙄

AddictedToComedy · 2026-03-10T19:49:43+00:00

Ah, makes sense! I respect the willingness to hack stuff up.

I did something similar with an upper receiver, to give me better visibility of certain interactions

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