Hopefully from all of these overlays I've posted it's clear that whether or not the overall length of my model is perfect, the features of the model are well proportioned and accurate to the hero. To provide some additional data points for the overall length discussion, I have been focusing in on the red button area. Lately I have been playing around with scaling the model between an overall length of ~290mm up to 300mm. Essentially I proportionately shrink/enlarge everything, but the red button, the covertech, and the rubber washer under the red button.
One thing I noticed was that when you get below overall lengths of ~290mm, the rubber washer under the red button starts to overlap with the last grip groove, something that doesn't happen on the hero or resin stunt sabers. Here's what I mean:
On the hero/stunt sabers however there is always the slightest gap. I put together this collage using publicly available references:
Well yeah, but it's a rubber part that is squished down by the red button, how can I be so sure I have the model dimensions for the rubber washer correct? Well I have a correct real hydraulic port plug (red button) and I have several hundred correct real rubber panel lamp gaskets (aka rubber washers) so I took a whole bunch of measurements. Using the red button I squished down a bunch of the rubber washers and measured the diameter with calipers. The overwhelming majority of the measurements were in the 19.5mm - 20.0mm range, with 100% of the measurements in the 19.5-21.0mm range. So I updated the model of the rubber washer to be 19.5mm OD and played around with the scaling. I would scale the model to various overall lengths between 290 and 300mm as I mentioned above, I would update my overlays to get as perfect of match as I possibly could, very precisely moving the rubber washer so it lined up with the reference image I was overlaying. Then I would look straight down on it and see if it would overlap the grip groove. Even at 290mm it very slightly overlaps the groove, in fact that's the example image I posted above.
Now overall this was not a very scientific approach, I'm not going to use this method to conclude any specific overall length. This was more a qualitative analysis to help bound the problem at hand.