Anyone familiar with this YHM flash hider/suppressor mount?

[tobnpr]

Customer sent me this (discontinued) suppressor mount from YHM (18 tooth) to install.
It's odd in that it has a non-threaded section with an ID of .782 behind the threaded section (5/8"-24t).

I called Yankee Hill, they asked for a model number but there isn't one engraved on it. They told me to email a pic, never heard back.

This design makes no sense to me, the back end is thin, doesn't look like it's meant to be the torque shoulder.
In the case of this customer's barrel (a fat shorty .300 BK), I'd need to turn down the barrel OD behind the tenon shoulder to get this section to slip over the end of the barrel.

Anyone seen this before?

 

[Khornet]

I looked at my YHM QD adapter and this one lacks snap ring, groove for it, spring and collar. My internal threads are much closer to the barrel contact face and no shoulder. Not sure what you have there?

 

[PRR1957]

I’m guessing it’s designed to work with a certain brand of suppressor with regards to the external course thread. I’m also assuming the oddly shaped blocks ringing the flash hider is to lock the suppressor in place once threaded on.

 

[tobnpr]

Found out it's for an AAC can.
I do need to socket the mount over the barrel shoulder so it bears on the inner ring (figured as much, no other way to do it that I could see).

 

[WSnyder]

Maybe this one?

 

[tobnpr]

^^^
Thanks- could be, the .750 unthreaded section would work with the .782 ID, need to check the depth.
Seems odd to me that there would be cross-compatibility between YHM and AAC but apparently that may be the case.