Everyone and their neighbor refers to the large ARs as AR-10s, it's common as all get out. You did specify DPMS and that's to your credit. I'm not jumping you here, but trying to explain why you would be asked to differentiate. Future questions about modifications to your rifle, or someone else's rifle, will likely be contingent upon the specifics of the brand/model. Calling everything an AR-10 causes problems when we make recommendations based on invalid information.