I have recently bought 20 tins of 4.51s from intershoot with an old school hollow interior. They appear to group well but make the barrel dirty very quickly, though my Steyr still has its new-type plated barrel and is a bit fussy. I'm not looking forward to running out of my batch 34 mega slugs.
I'd go with Dan here, the quality (that is weight conformity, size etc.) does appear better than ever, I have dregs and half tins going way back and none are quite as good as the latest batches and lots are far worse. However the old ones generally shoot better and tend to be a different design. I guess it shows its the design that counts and not just pure quality. The ultimate example of this is the superb consistency and quality of H & N pellets and their very mediocre accuracy and shocking ballistics. What we need is for H & N to start making hollow skirted Exacts!
No one tries to make a bad product and it must be as easy (or hard) to make them hollow or filled in. The thing that takes effort must be all those measurable factors that have actually improved.