What's the word on these? I'm thinking of doing a "one stamp" carbine....9" .300blk barrel and a pin/welded suppressor under the handguards.

Talk me out of it.

Heat transfer through the handguard.
Marriage to the suppressor.
Can't use suppressor on more than one host.
Lack of ease of cleaning the rifle.

Don't know anything about that particular can, though, but "one stamp" suppressed rifles have always struck me as too limited by their downsides. The primary benefit is saving $200 (plus the cost of engraving the lower), but if you can use that can on even one other gun, you likely make that up (and then some).

Also, you might want to double check the length. According to the GA page, the suppressor length is 7.23”. If you only have a 9” barrel, you are probably going to be under 16” since there is likely going to be about 0.6” of overlap at the threads, which makes the OAL less than the sum of 9 + 7.23