The process of dry fitting, PVC pipe(s) and fitting(s) is fraught with problems. This is because the industry standards for both the pipe and the fitting socket are designed to provide an interference fit within the bottom 1/3 of the socket. This is where the solvent in the cement creates a fusion bond of the pipe and fitting. The socket of the fittings have a slight taper, to assist in rounding the pipe and achieve the fusion bond area necessary to provide a leak free, joint that can withstand the forces of the system pressure.
Sanding or grinding the diameter of either the pipe or fitting can jeopardize the quality and/or performance of the solvent welded joint.
Pipe fitters that fabricate pipe assemblies use the takeout dimensions provided by ASTM standards for PVC fittings. These dimensions can be found within ASTM D2467. Another choice for getting the takeout for PVC fittings can be found at: http://www.expert4pvc.com. There are two FREE options that can provide you the takeout you are seeking. First is the html page at: http://expert4pvc.com/HandyTools.html or the Android app at: http://expert4pvc..com/Android.html