I currently run a sdn6 on my 556 AR's and It works great but I'm thinking about upgrading. I also have a ultra 9 that should be out of jail any day now so I have should have .30 cal covered. I've been looking looking at gemtech g5t, sig 556ti and thunderbeast 223 cb. Any dogs in that group or am I missing any standouts? This can will mainly be used on a precision ar and a future 223 bolt gun. Weight and accuracy are primary concern. The ar gets used for prairie dog hunting and will sometimes be shot approx. 250 rounds in a hr but I don't think that will mandate a full auto rating. Thanks

Specwar 556K maybe.

SIG 556TI is vaporware until they make some.
G5T is getting a free tax stamp over at Silencer Shop right now
Thunderbeast 223CB is discontinued, replaced by the Ultra 7 223. You might be able to find a deal on one from someone who still has them in stock.

Best of luck on your search.

556SD?

Quite a value...