Muzzle device?

As in it goes onto the barrel of my AR but also has 1/2 x 28 threads on it to make it so I don't have to keep taking off and putting on my muzzle device every time I switch my direct thread suppressor to a different AR?

I have never seen one.  Most muzzle devices that are threaded externally use a larger thread positioned toward the rear of the device.  This design wouldn't work well with a 1/2x28 external thread.

I'm confused as to what you're trying to accomplish.
I read that you want a device to screw onto your barrel's 1/2x28 external threads that has 1/2x28 external threads on it?

He doesn't want to remove his muzzle device to use his screw on suppressor. Basically wants a ported barrel extension. Would need turned on the barrel itself to be concentric for the suppressor to be lined up. Then it'd hurt the threads of the suppressor when fired.

Ive never seen this commercially available.
It can be a custom piece, with possible issues.
You'll have a protrusion from the front of the mount. Can your suppressor(s) accomodate this?
Being a custom piece, not 100% how well it will perform when not attached.

1/2-28 UNEF-2A thread minor 0.455
Bore diameter 0.250 - 0.265
Max material left, per side, 0.102 (max) <-- not awesome, for a brake, but doable with right material.

Yeah I didn't even think about that. I'm totally new to this and my ignorance is showing I guess. I don't have a problem with direct thread I'm just a tad nervous about having it come unscrewed.

Is it something that you constantly have to check every x amount, or after a certain amount of rounds it's on there and isn't coming off without force?

Two things are going to occur.

1. Either you have a muzzle brake/ported section that has only about 0.100 wall thickness and isn't very effective, and also will reduce the effectiveness of the suppressor and possibly cause damage, as now this extended barrel nub is protruding into the blast chamber

2. Or you thread the end of the device, and have the muzzle brake before the suppressor, which results in an effective brake, but makes the suppressor useless.

If you are using a direct thread suppressor, I would just use a simple knurled thread protector on the rifles you regularly use as hosts, and not worry about dealing with a muzzle device.

if you did get something like this created... you'd still be direct threading it to the muzzle device anyway.