I would have to check-Whatever gets them to shoot the best.
With good muzzle brakes
and using riflescopes that have the better eye reliefs it has not been a problem.
On some rigs I don't see a full field of view.
The surface you are shooting on makes a big difference as well.
If it is a slick/smooth surface the gun is going to come back more than off of a bi-pod shooting on dirt.