HAO 4140 Steel made 4"/ 6" extension tube with 14mm CCW thread can turn your 10.5" 416 into a more accurate firing platform.
 
You can also find the accessories in the photo here:
 
SMR handguard:
https://www.haoptwart.com/product-page/g-style-smr-handguard-for-vfc-hk416
T1 red dot mount:
https://www.haoptwart.com/product-page/hao-g-style-t1-mount