Re: ar 15 top on AR 10 bottom
No you can not do that they are diffrent sizes.
Not to mention there is no standardization at all with the AR10 platform. AR10 is an Armilite rifle and is not compatable with say an SR25, MRP etc.... most of the time the magizne wells arre not even the same.
If you would like other sugestions I have them but they will cost more money and I am assuming if your talking 338 Federal your looking at a DPMS wich is bottom of the barrel in the AR world.