So I ordered an AR-10 build kit from Seekins to build a nice "precision" gun. I'd like to also build an upper with a shorter 308 barrel and with a lighter handguard. Problem is that Seekins kit come with the warning "we do not recommend interchanging our receivers with other SR25 receivers to ensure the best receivers fit." Is that just a standard CYA or are their receiver sets really that tight. If it isnt a big deal, what have you guys used that works?