I do not know the topic extremely well,but there is an M-4 ramp,and there is the standard AR ramp.The M-4 ramp is cut a bit deeper and the bbl extension cuts should blend with it.I cannot tell if you have a problem.If it is incorrect,contact whoever built your upper.IMO,charging in with a dremel is usually ill advised.That black anodize is a wear resistant hard coat.The aluminum under it is pretty soft.
An engine builder might "massage" a piston.Breaking all sharp edges,etc.This sort of fine hand work can be done by a man building his own rifle.It is not likely in production.You do not have access with an assembled upper reciever,If you had only a bbl and bbl extension,you could lightly break all sharp corners,draw stone and lightly polish the ramps,etc,and that would be sweet.I also think 99.9% of the production of AR type rifles have not had this done,and they work.
Another grim possibility,you say you saved a lot of money gathering parts and assembling this rifle.Cool,I assemble mine,too,but I cannot say I save money as I buy what I consider quality over cost.It may be possible that a bargain reciever is not quite Mil-Spec.(And maybe you have top quality stuff so it isn't the problem)
Of course,the bent round would impede bolt closing and feeding.