Don't change stocks, you just need to fix the fit of the one you have.
Does the stock have play at the cross-bolt or is it tight there and thus pivot, or rock, at the back against the FCG? Sometimes it is not noticed because o the tension spring underneath the FCG in the stock.
If play at the cross-bolt then shim or build up at the cross-bolt. If it rocks/pivots at the cross-bolt then shim/build up under the FCG around the tension spring.