I'm testing out one of those "PelletGage" thingys from the US at the moment.
I'll be honest, I'm not going overboard on spending much time on testing/measuring because ultimately I don't think it's worth the effort.
What I've been surprised to find so far is that my current batch of pellets (Die 19, 4.51) out of 200 that I measured, around 160 of them came in as 4.51, 39 of them came in at a tight fit in the 4.50 hole and 1 came out as a tight fit in the 4.49 hole.
I shot some groups with both the 4.51's and 4.50's and I couldn't tell any difference in group size.
I chucked the 4.49 away.
Die 19 is the one I tested a while back - downrange group size, downrange chrono, BC's etc etc.. Die 19 came out on top easily, which is why I bought a load of them!. I'm coming to an end of that supply now, probably got enough to see me through the Worlds if I don't use them for my standing practice.
When I'm loading a pellet in the barrel, if one feels very loose or very tight, I'll just fire it off into the ground, so I reckon using that approach I very probably would have spotted the 4.49 anyway.
The rest of them... well, I can happily just carry on shooting them straight from the tin, I don't intend to do any weighing, measuring, polishing, sizing etc.
I might use the PelletGage again when it comes to finding my next batch later in the year.
I might also have a go at measuring one of the batches that didn't do so well in my pellet selection tests to see how consistent they are for head size and how the size on the sticker relates to the actual size of the pellet.