Hot temp possible thermal shift

[GJM]

Friend of mine left his 320 Legion lower, GGI Lockwood upper with a direct milled Romeo 3XL in his trunk in Phoenix for about ten days. Guessing, but temps in the trunk had to be quite a bit higher than the ridiculously hot ambient.

In any event, his zero moved nearly eight inches at 25 yards, both windage and elevation, from his spot on zero that he had at Nationals. While theoretically there could be another explanation, the extreme heat is at the top of the list.

I am wondering what experiences others have had with extreme heat and pistol optic zeroes?

[rdtompki]

Friend of mine left his 320 Legion lower, GGI Lockwood upper with a direct milled Romeo 3XL in his trunk in Phoenix for about ten days. Guessing, but temps in the trunk had to be quite a bit higher than the ridiculously hot ambient.

In any event, his zero moved nearly eight inches at 25 yards, both windage and elevation, from his spot on zero that he had at Nationals. While theoretically there could be another explanation, the extreme heat is at the top of the list.

I am wondering what experiences others have had with extreme heat and pistol optic zeroes?

Call the manufacturer and inquire about maximum storage temperature. Unless that RDS is designed to Mil specs I can't imagine it's ok in a car trunk in Phoenix summer heat. Black car would be the worst.

[Archer1440]

You could expect up to 160ºF in a closed car in PHX on a sunny, 100ºF day, and it was considerably warmer than that this past week.

However, even with the CTE differential of the materials in the sight, I would expect an RTZ after normalization of the temperature.

Did your friend drive from (CO?) Nationals to PHX with the pistol in the trunk? If so, I would nominate vibration as a possible contributing factor.

[HCM]

You could expect up to 160ºF in a closed car in PHX on a sunny, 100ºF day, and it was considerably warmer than that this past week.

However, even with the CTE differential of the materials in the sight, I would expect an RTZ after normalization of the temperature.

Did your friend drive from (CO?) Nationals to PHX with the pistol in the trunk? If so, I would nominate vibration as a possible contributing factor.

How about elevation/ pressure changes ?

Also how sure are we that it was the optic ?

AZ summer temps can warp polymer grip shells. In particular, the competition for frames that have the tungsten powder mixed it are known for being brittle / fragile enough SIG warms against using them for duty applications.

[GJM]

There any of a number of possibilities besides heat, but it has been extremely hot in the Phoenix area lately. He flew back and forth to CO Nats, and the car was parked with the pistol in a padded case.

Since we are experiencing intense heat, a lot more pistol optics are likely being exposed to more heat than typical -- will be interesting to see if any trends emerge. In the interest of science, some of you ought to leave your pistol
In the car and check zero with the Wheeler.

[farscott]

Unlike the Aimpoint Aero P2 web page that specifies an upper ambient of 160 degrees F, the SIG website has no information about the upper ambient rating for standby or operating. My daughter lives in Phoenix and temps have been around 115 degrees F. 45 degrees F of temp rise in a vehicle is not unusual or extreme.

As to what fails, my guess would be mechanical, not electronics, as most industrial electronic parts today are rated for 85 degrees Celsius (185 degrees F) at a minimum. There are some parts (commercial) rated to only 70 degrees Celsius (158 degrees F) but those parts are now usually the industrial parts without additional screening or parts that function but are outside of norms.

[GJM]

Early on, the Romeo 3 Max and XL had some zero issues due to a loose screw that held the windage and elevation adjustments, but Sig fixed that, and I no longer hear of this as a problem. Odd the zero on my friend's pistol moved in windage and elevation.

[1911Nut]

My perfect alibi/excuse/rationalization for discontinuing participation in shooting competition here in Phoenix back in May!

I think today was the 27th consecutive day of temperatures at 110 degrees or higher here in Phoenix and the current forecast is predicting three more days until it "cools off" to 109 degrees on July 30.

That's too hot for me, my pistols, my ammo, my dog, and my wife, and we are all natives!

I was cleaning a pistol this afternoon and removed the slide and gave it a good scrubbing. Separated the barrel and RSA and took the slide outside my work area to blow it off with compressed air. Took about a minute or two. When I was done, I set the slide down on a towel on top of a nearby retaining wall while I shut off the air supply and rolled up the hose. It couldn't have been on the wall more than a maximum of 3-4 minutes, for a total time in the sun of 5 or 6 minutes.

When I picked it up, it felt like it had been in a pizza oven for half an hour, and I thought I might have burned my hand!

I'll be in my climate controlled RV garage dry-firing until October!!