[High Desert Flipper]

I'll second the skepticism above, very very few have broken the 500 fps mark here so 800+ fps seems pretty amazing.

It also seems like this would be pretty easy to test / replicate. Lots of people with chronographs here, and setting up a heat pack in an insulated bag like you suggest or getting some hot / boiling water to soak your bands in right before shooting over the chrony shouldn't be so hard.

It would be interesting to see if somebody could replicate this. 🤔

On the flipside, many here have tested the cold tolerance of bands and found that some of the "cold tolerant" brands (Simpleshot and others) do slow down a bit in cold weather but give up less than 10% of velocity going from a near freezing morning to a pretty (80 degree F) afternoon, so the cold tolerant bands really seem to be pretty good.

 

[High Desert Flipper]

I agree testing is a great idea. Being skeptical is one thing, but actually trying to repeat it is another. I would have saved myself eating a lot of crow over the years if I had tried to confirm everything I didn't believe at first. And yes, this seems pretty magical fantastical, but I'll feel better about accepting or rejecting it when somebody tries to repeat it independently. I may even give it a go at some point, though it will be a while. I have several other things on my list to try and haven't had time to get to those lately.

 

[High Desert Flipper]

I will test it in autumn and winter with the IR thermometer.

Cool! Will be fun to see your results. And who knows, if things go well maybe you will become the first and only member of the "800 club" here. I'll be interested to see how it goes.