CCG
Thanks for researching the book for me. Sitting is actually my favourite and best shooting position. I sit x-ankled, elbows forward of my knees. Slung up in approved USMC, I can shoot as well sitting as prone out to 300 yards. Most guys I know never shoot sitting (can't get past the bulge over hanging the belt) or even practice field positions of any kind.
I'e been known to shoot sitting at 50 yds while hunting, if time permits. Why? because it allows me to surgically place the bullet.
As for the alleged "600 yards+" attested to by Mattie, I think 200 yds will be enough of a stretch for my CAS pals. I've got a Shiloh Sharps carbine and military rifle in 50-70, my favourite BPCRs. It wouldn't occur to me to even try a shot at 600 yds, but then, I've never had to save a buddy facing imminent death.
The trajectory would be like a rainbow arch .... :>)