They have them listed as in stock.
https://www.rksusa.net/HK-416A3-ADJUSTABLE-GAS-BLOCK-p/203659.htm
The actual page on the site says 10.4” vented gas block not A3adjustable gas block and the picture shows the same. You might call to verify before buying.
https://www.rksusa.net/HK-416A3-ADJUSTABLE-GAS-BLOCK-p/203659.htm
The actual page on the site says 10.4” vented gas block not A3adjustable gas block and the picture shows the same. You might call to verify before buying.