Is this for the PDI AEG barrel you were talking about? If it's for sniping you might want to get the window lengthened if he provides that for the heavier weights.
No i decided against the PDI in my VSR and got the EdGi barrel. Currently got the PDI W hold bucking in it, see how it performs otherwise It'll also be going to KOA for an Rhop. For the EBR I was just going to put a ZCI in it as I've had good results with them in AEG's and flat hopped.