I’ve always stayed away from adjustable gas blocks due to not wanting an extra fail point. However, my shooting has shifted to pretty much 100% suppressed. My latest build has a BRT gas tube with a smaller diameter and it’s helped tremendously in limiting gas in my face. But now I’m curious about adjustable gas blocks again.

Are there any adjustable gas blocks that has some sort of fail safe? Where in the event the detents/springs/set screws/whatever has a failure, it will still operate either in the last position or in a full gas position?

Thanks in advance for any guidance.

I have a couple of guns with AGB's, but they are the "set it and forget it" type with an allen screw to regulate the gas and another allen set screw that tightens against it.  I do not see any chance of a failure with them.  The issue with many AGB's is that they often get carbon buildup and freeze up unless you constantly are adjusting the gas.  That is not the reason I have AGB's.

The only way I’m going adjustable gas block is if it comes from the factory with one.

My Honey Badger for example. I got it dialed it to run with a particular suppressor on subsonics and that’s the only way it gets shot.

Set it and forget about it. No issues with it at all.
The set screws are tiny though. I wouldn’t want to constantly be adjusting them.

OP, there are adjustable gas blocks;

There are gas port regulator disks that insert under the gas block;

As you've found, there are various diameter & shaped gas tubes, and I think there used to be a variable gas tube;

There was an adjustable upper;

There are adjustable gas keys;

And adjustable gas bolt carriers.

I don't get your point. Why does an adjustable gas block have to come with an AR you bought? It's just a 300 Blackout. Apparently you "got it dialed in" with a specific suppressor. What's the difference between that and using an adjustable gas block with a 300 Blackout someone built? It doesn't make any sense.

This. I'm not currently running one, but I have. I screwed with it until I got it dialed in right where I wanted it, then left it. If you want something to constantly mess with pay for the riflespeed one. If you just want to tune it and leave it be, my SLR worked great.