I have two of the SPS Tactical AAC-SD's (don't ask..lol). The Hogue stocks are really weak on those. I had a lot of flex from them. I ended up stiffening the stock by using an epoxy to fill the lands in the stock. It did add some weight but only a few ounces. I would recommend buying a B&C medalist or McMillian. If you don't mind the extra cash go with a Manners Chassis.
You can also (beside the epoxy) use a dremel and cut the barrel channel a bit.
If it flexes enough to touch the barrel, it can definitely cause some accuracy issues.
" The strongest reason for the people to retain the right to
keep and bear arms is, as a last resort, to protect
themselves against tyranny in Government...." - Thomas Jefferson