Hi XXXXX,

Thanks for the email about the UH-1.

Regarding the thermal drift, the last time we tested it was on some of the earliest UH-1’s and we have made some improvements since then, but we haven’t re-run the test. The reason being that we are currently developing a better test method that will test some additional factors, such as how well the sight holds up to shock with freezing and heating, or how it handles POA shift with shock in hot or cold.

Anecdotally, I can tell you it holds up well to these things, but we want to be able to quantify it.

That being said, what we found with the early UH-1’s is that they saw a maximum drift of +/-1.5MOA from -40F to 140F. Almost all of this drift happens at the extreme ends of that range though. From about 0F to -40F and 110F to 140F. In other words, there is almost zero drift between 0F and 110F.

I expect that they are even better now, due to some internal upgrades we made shortly after their release. I just don’t have hard numbers for you.

I hope this helps. If there is anything else you would like to know, I’d be happy to help.

Thanks.

Sam