So there is a 5/8-24 version of the 1/2-28 MD that came out this year to allow 5.56 guns to run the 7.62 QDC suppressors.
It isn't on KAC's site yet but I did find (of course, its out of stock) it on OP's site:
I have a Mod 2 SR-30 in NFA purgatory. My local dealer always let's me just leave the lower, so I have the upper in my possession (I have SBR lowers I could run it on too if I really wanted to) but then I decided why put up all the waiting. I got some SBA3s and ordered a few lowers but thought I'd leave the upper sitting for the lower when the form 4 clears. The idea being I'd run my SBR with a dedicated 762QDC with subs at the house and then use the "pistol" with irons as a "truck gun".
I ordered a new 9.5" Mod 2 upper for the pistol lower and it came with the new muzzle device. I had already ordered a 5/8-24 MAMS to run on the dedicated suppressed SBR (following the sacrificial baffle concept) but after doing this comparison I may change course:
So the new MD is nearly an inch shorter than the one designed for the SR-25. Also, the wrench flats (in an ingenious move, IMO) were placed FORWARD of the QDC mounting area so that even suppressed there will be a reduction in OAL.
I'm thinking now whenever OP gets one in stock I'll just order the new MD to replace the long, SR-25 one. The new shorter one will be great in a discreet backpack I believe. Good move by KAC by taking this 5.56 device and applying it to the SR-30 line.
I haven't fired either upper at all so I can't comment on how the two designs compare at night when it comes to flash suppression.