Your thoughts on 455 Evolution stock

[bravo5two]

I picked up a new 455 Evolution with blue/gray laminated stock, nice gun.  However, upon my first range trip shooting off sand bags, the rifle kept sliding off due to the sloping front.  I'm thinking maybe a section of rail & bi pod would work better than sand bags.  Your thoughts/experiences on this?

The more pricey option is to get a chassis, which will virtually doubled the investment cost for this rimfire 

[Blackwatch]

I've found putting my left hand between the stock and a sandbag helps to stabilize it...obviously keeping the rifle tight into the shoulder as well.
With good ammo - very consistent and tight groups!