I guess it depends upon the sponsoring organization. With the NBRSA, there is no longer a rule that the rifle has to be able to be lifted out of the front rest. Edgewood started offering a front bag that folded over the top of the stock somewhat after that rule was changed. Current front sandbag rule is basically that the sandbag has to be at least 1/2” thick and filled with sand at any place it contacts the forend. This change allowed separate bags to be used on the sides as well as a bag or combinations of bags under the forend. Basically, the new front sand bag is very unrestrictive and allows for a lot of lee way into how you can support the forend of the rifle. This change to the rule made the bag that Seb makes for F Class shooting that had separate adjustable sand bags on each side of the rest that could be moved to accommodate varying widths of stocks a legal sand bag. It also dipped down slightly in the middle. Edgewood came out with the drop out bag that doesn’t make contact with the center of the forend after the last front sandbag rule change. IMO the less restrictive we are with rules, the better off we are as to meeting the primary objective of the NBRSA which is the development of extreme accuracy in rifles, ammunition, equipment and shooting methods. We’ve improved our equipment so much now that it’s pretty hard to gain much in the way of accuracy. Just about everyone is shooting pretty well the same equipment anymore. Hard to innovate something that is better.