Scope temperature shift fixes

[drsquall]

I know scope shift temp changes happen with many brands of scopes which affects ranging and poi changes. How do you guys try to alleviate this as much as you can? I know trying to keep gun out of direct sunlight but that's not always possible. Cavedweller mentioned putting a white towel over it and he said it helped there in Alabama where it gets pretty hot like here in OK.

What else helps with this? Do you just figure out the temp range that it occurs and how much?

Or just get a scope that doesn't have that issue?

Thanks
Jon

 

[John "spysir" Blount]

Certainly shading it is a good idea. A friend from the GOB who is an International shooter who uses a leupold 45x . In blazing sun cover with towel when not shooting but mainly knew where the temp change was (and effect elevation only, not ranging) and had a temp strip - like an aquarium but I believe medical grade- and added 3 I believe clicks at 84 degrees. Didnt seem to change except above or below 84. Do remember esp. depending on rifle type the rifle itself may change due to temp. Pretty well a fact on many whiscombes but again usually just one shift with temp change. Cover the entire rig between shooting. I've seen people try fancy scope heat shields but they abandoned them so?
Never heard anyone really talk about it but for me with an aluminum scope tube aluminum mounts like BKL just to keep expansion close to the same?

John

 

[Sqwirl57]

Hear me out.... Martini umbrellas and a little duct tape

On a serious note, my X50 shifts up a bit as it heats up. I have one of those fish tank temp strips on my scope that was recommended by someone else and it does give a pretty general idea of where my scopes temperture sits. A couple clicks here and there seem to do the trick and I can typically use the shorter range shots to see if there is any noticeable discrepancy between my POI and dope sheet.

 

[qball]

Simple towel or sunshade of some kind over the scope when not in use.

Or if you have the coins get the March highmaster series scopes.

 

[BackStop]

Serious question:

How do you know that it is the scope causing the shift because of temperature and not something else?

There are several things that can cause elevation POI shift. Some involve temperature and others involve pressure.

So, again, how can one test to be sure it is the scope reacting to temperature changes and not something else?

Thanks in advance!

 

[BackStop]

@drsquall

What gun and scope are you referring to with your OP question?

Did you add a barrel band to that gun?

Although a lot of folks like to add a barrel band to their "free floating" barrels, it can have the negative effect of causing POI shifts (usually elevation) as the pressure changes in the main pressure tube where most of these barrel bands are anchored.

Another thing to consider is that atmospheric conditions can also influence POI and much more (if you are a precision nut like I am) than many people know or understand.

BTW, "free floating" can be a bare barrel or a shrouded barrel. At least in my limited experience, it is best to keep the gun as designed and look for other reasons for POI shift before ever adding a barrel band that can cause more problems. JMHO

Oh well, I am an amateur with limited experience, so take what I say with that in mind. (smile)

 

[drsquall]

It's a sightron FT that does it on any gun I put it on.

 

[Chas DiCapua]

One solution is an adjustable pointer. It has marks on it and you just range you distances at different temperatures and know what marks to shift to.

My sightron has a farily big shift at about 78 degrees, but also continues to shift as it gets warmer and cooler. Just have to take the time to know your scope. Yes, as someone mentioned, those sticky thermometer tapes help you know what temperture your scope is at.

 

[Sqwirl57]

Serious question:

How do you know that it is the scope causing the shift because of temperature and not something else?

There are several things that can cause elevation POI shift. Some involve temperature and others involve pressure.

So, again, how can one test to be sure it is the scope reacting to temperature changes and not something else?

Thanks in advance!

It can be other things as well especially in a springer. The common issue is in the optic though. Shoot out your window at a target and get your gun nice and zeroed. Now take a hair dryer on low setting and warm your scope up for a bit and shoot another group. Where did your POI go?

 

[BackStop]

It can be other things as well especially in a springer. The common issue is in the optic though. Shoot out your window at a target and get your gun nice and zeroed. Now take a hair dryer on low setting and warm your scope up for a bit and shoot another group. Where did your POI go?

Not exactly what I would call a good test, but then I have never experienced what you and the OP are suggesting is happening.

At least I found other things that were influencing my POI shifts that I don't believe had anything to do with the temperature of the scope.

However, I will try your test and see if it makes a difference. It may be a while before I remember to do it, but I will let you know if I experience any POI shift.

Unless I misunderstand, the OP (drsquall) said it only affected "ranging" and not windage. That makes me think there is something else going on.

Why would it ONLY affect elevation and not ever windage? Curious.

Thanks for the replies. I am still thinking there is something else going on. (smile)

 

[cavedweller]

This temp shift is a “thing” on many scopes including sightron and Nightforce - direct radiant sunlight on a hot day will make you crazy - some YouTube videos available and plenty of discussions - wrapping scope under Ring’s with 2 turns of Teflon tape is one recommendation and Burris xtr signature Ring’s have plastic inserts which help but avoiding direct sunlight is the best solution I’ve found so far.

 

[BackStop]

One solution is an adjustable pointer. It has marks on it and you just range you distances at different temperatures and know what marks to shift to.

My sightron has a farily big shift at about 78 degrees, but also continues to shift as it gets warmer and cooler. Just have to take the time to know your scope. Yes, as someone mentioned, those sticky thermometer tapes help you know what temperture your scope is at.

Well, could this be a Sightron issue? I mean, here is another person claiming POI shifts due to temperature using a Sightron scope.

Don't get me wrong, I am not doubting either the OP or the poster I am replying to. It is just something I have never noticed or even considered as I found solutions that never involved the temperature of the scope. However, maybe the fact that I simply didn't consider it is also a factor. (smile)

Anyway, again, the fact that it ONLY seems to affect ranging and not windage has to make one wonder... (smile)

 

[Sqwirl57]

Not exactly what I would call a good test, but then I have never experienced that you and the OP are suggesting is happening.

At least I found other things that were influencing my POI shifts that I don't believe had anything to do with the temperature of the scope.

However, I will try your test and see if it makes a difference. It may be a while before I remember to do it, but I will let you know if I experience any POI shift.

Unless I misunderstand, the OP (drsquall) said it only affected "ranging" and not windage. That makes me think there is something else going on.

Why would it ONLY affect elevation and not ever windage? Curious.

Thanks for the replies. I am still thinking there is something else going on. (smile)

You really don't need to let me know. I've already done it. Its kinda how I know it's a good test and why I recommended it

Its a fairly common issue especially in field target where you're bouncing from cool shade to direct sunlight, especially in the summer months. Black scopes absorb heat quickly. And no, it isn't just a Sightron issue. I've seen it to some degree in every scope I have.

 

[BackStop]

This temp shift is a “thing” on many scopes including sightron and Nightforce - direct radiant sunlight on a hot day will make you crazy - some YouTube videos available and plenty of discussions - wrapping scope under Ring’s with 2 turns of Teflon tape is one recommendation and Burris xtr signature Ring’s have plastic inserts which help but avoiding direct sunlight is the best solution I’ve found so far.

Of course, if it was posted on Youtube it MUST be true! (LOL!)

Without going to Youtube, I am going to assume that these also show POI shifts in elevation/ranging only.

If scope temperature is causing the issue, it seems likely that there would be windage issues as well.

Oh well... there was a thread recently "Best excuse you like to use". (grin)

 

[drsquall]

Of course, if it was posted on Youtube it MUST be true! (LOL!)

Without going to Youtube, I am going to assume that these also show POI shifts in elevation/ranging only.

If scope temperature is causing the issue, it seems likely that there would be windage issues as well.

Oh well... there was a thread recently about what is your excuse... (grin)

Everyone who has sightrons will tell you there is a POI shift at certain temperatures

 

[Solo1]

I talked to an athlon rep at pa cup about temp affecting ranging on their scopes and he said it was a possibility because if the tube expands enough it would change the fitting of the parts in the tube for the ao. Try keeping it out of direct sunlight

 

[BackStop]

Everyone who has sightrons will tell you there is a POI shift at certain temperatures

I did find this recent posting https://shooting-the-breeze.com/threads/sightron-poi-shift-with-temperature.61030/ specifically about Sightron scopes.

However, I still find it odd that it seems to ONLY affect elevation, but not windage.

Even considering what was observed in the posting I linked to above, the entire gun is heating up in the sun/sun lamp, not just the scope. So, there is always that to consider as well.

In any case, it is not something I have personally observed... so far. But now that I am aware that it could be an issue, I will add it to the long list of reasons why I miss my shots. (grin)

My best to all!

 

[Smok3y]

Of course, if it was posted on Youtube it MUST be true! (LOL!)

Without going to Youtube, I am going to assume that these also show POI shifts in elevation/ranging only.

If scope temperature is causing the issue, it seems likely that there would be windage issues as well.

Oh well... there was a thread recently "Best excuse you like to use". (grin)

You are asking good questions. The issue is a ranging issue, not really a POI shift issue.

The issue is that: You ranged your tape at one temperature at 30 yards. At a new temperature, the range says 28 yards, but you are really at 30 yards! So, you shoot at a target you think is 28 yards, so you miss. You have to find your temp shift range, so that you know once you get to another temperature and it says 28 yards, you effectively have to put in the adjustments for 30 yards, because you are really sitting at 30 yards.
If you are not side focus ranging for distance, but instead using a laser range finder, you wouldn’t have the issue. You would know you are at 30 yards and make the adjustment for 30 yards and hit your target.

 

[Sqwirl57]

I did find this recent posting https://shooting-the-breeze.com/threads/sightron-poi-shift-with-temperature.61030/ specifically about Sightron scopes.

However, I still find it odd that it seems to ONLY affect elevation, but not windage.

Even considering what was observed in the posting I linked to above, the entire gun is heating up in the sun/sun lamp, not just the scope. So, there is always that to consider as well.

In any case, it is not something I have personally observed... so far. But now that I am aware that it could be an issue, I will add it to the long list of reasons why I miss my shots. (grin)

My best to all!

It affects the ranging/parallax most. If you range something at 45 yards using your parallax wheel and its actually 50 yards, your POI is going to be much lower than expected. Other things are affected as well but keeping track of the ones you know are an issue minimize the error involved.

 

[AirShot]

Going from hot to cold and back makes things expand and contract, no way around it, all scopes do it, some more than others. On your particular scope thorough testing at different temps is the vpbest you can do. Limiting the scope to big temp changes can help. But there is no scipope that doesn't expand and contract under hot/ cold situations.