22lr Temperature Sensitivity Questions

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Ridge-Runner

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I have a question for the folks shooting more long distance with 22lr PRS stye shooting. I have been playing with two ballistic calculators; Strelok Pro and Chairgun. I have a few questions I’m trying to figure out on temperature effects.

What temperature sensitivity range are you finding in SK and Eley and what value(s) for a temperature sensitivity factor (percent bullet speed will change at change temperature on 15 degrees Celsius)? Currently I’m using for SK ammos 2.6-4.8 and for Eley 1.6 to 1.8, which seems to be fine but I’m always tweaking at longer distances of 300M - I’m not sure if this is environmental or the prediction of my ballistic calculator. I fully understand the garbage in, garbage out theory and I’m trying to minimize this effect with temperature and how it plays into predicting accurate values at distance.

What Temperature Sensitivity Factors are you finding that works the best and do you always seem to have to tweak your ballistic data to make your bullet match the drag curve model frequently?

And lastly, do you use the Consider Powder temperature on your app, or do you turn it off and if you leave it on? How do you consistently determine what the powder temperature is for your bullets when shooting or what value do you use?

Thanks, any help will be greatly appreciated
 
Start with defining what your group size is at 300... I suspect it is a lot larger then you are expecting. You may not need to adjust anything as the group size and center may be varying just due to the mechanical cone of your set up.

wind can also have a massive affect that far out so you have to know what is the air pattern you are shooting through. Mirage and wind flags are your friend.

Consider using Lapua CenterX or a higher grade, or High grades of Eley... if your rifle will shoot these ammos, hopefully, the cone stays more stable as the 'outs' will be reduced (maybe).

rimfire ammo is sensitive to temp... shoot over various temps and monitor the change. The app cannot account for all the changes within your system and you. Ammo is only 1 variable due to temp...

Jerry
 
Thanks Jerry, yes I understand what your saying and determine my group size by shooting a group of 30 shots and populate the center of the group by measuring all shots to determine the mean of the center, I shoot a CZ457 with an IBI 16 twist barrel in a MTD chassis and I use a lot of SK Long Range, Eley Contact and Eley Match. These group at 300m will vary in size from nine inches to greater depending on the day but I try and find the center each time unless they are too large and unreliable. At 300m, there is variability in group size day to day, I'm just trying to get my ballistic app to line up the best to realtime shooting with no tweaking each time I go out. My data works very well to 200m and I'm usually plus 2-3 MILS high at 300m.



I guess I'm new to the game and not sure what to expect in terms of ballistic calculator accuracy. I guess my core questions are;

Do you tweak your ballistic calculator frequently or do you set it and its good to go ?

What temperature sensitivity values are you using and how did you determine those values ?

Do you keep the "Consider Powder Temperature" setting on your calculator, off or on ?

What drag curve model works best for you in 22lr?

What do you consider acceptable accuracy from your Ballistic calculator at 300m, right on, within 1 mil, within 2mils, more mils ?

If I set my Ballistic Calculator and I test it, I find my morning cooler temps (10-14C) more accurate to line up with the calculator than I do in the afternoon when temps are 27-30C, if that helps at all ? This is where I'm wondering if my "Temperature Sensitivity Factor" is set too high ?

Thanks again and I'm just trying to learn and get the most out of my shooting.
 
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I am sure you will not like the following answer... I do not use an app. I get my data from real world shooting, verified over several trips. Once I have my dope card, I compare the curve vs big changes in ambient conditions. in general, my numbers don't change over the useable temps of the ammo and set up.... outside of what is caused by conditions like wind.

When looking at your group variations, just collect data on ALL shots fired. Over time, you will see that the varying group isn't... it just the composite of how that ammo works in your rifle at distance. Why I suggest your group is larger then you think.

As long as the group will let you hit an expected sized target, don't worry about the system and focus more on conditions which have a much larger affect. There aren't many shots past 250yds these days.

If you can find it, test SK rifle match and Lapua CenterX just in case your barrel doesn't like the faster ammo. I have never been able to make SK LRM work in my rifles... many others have. My barrels just prefer going 'slow'.

It is not uncommon to see a 1 to 2 mil change in impact with a 'small' change in wind. Best way to practise is over wind flags and video from you to the target... hopefully, you will be able to keep a mental note of the group you shot vs where the bullet landed. Then compare to what the wind and mirage was doing... maybe it is ammo and rifle... maybe it is just the air swirling around

Learn how the air moves at your range... what range are you shooting at? or what is the terrain you are shooting over?

Lots to learn...

Jerry
 
Consider putting up a target at 150, 200, 250, 300... collect the real world drop at cool temp... collect the data at hot temps. Use the app to get you on paper, use the target to determine the correct value.

do this a few times to make sure that each data set per temp repeats. now figure out the temp limits when things change.

When shooting be aware that as things warm up, your drop will change. As your impacts go higher as temps warm up, you can adjust in real time gradually between the cool and hot dope card.

Voila...

Jerry
 
My SK S+, SKRM, and SKLRM all showed significant velocity change from 5C to 25C. Approximately 50fps. My Eley Match shows 10 fps faster at the higher temp verge lower one. At 275M, my elevation required for Eley Match will vary 0.2 mils over the different enviro conditions at the start of a match vs mid afternoon. It is very difficult to account precisely for all the environmental changes using paper and pencil vs some kind of ballistic calculator. Of course, you must true the calculator you use to your results on paper along with solid data entry. Until I upgraded to Eley Match from SK, my groups at 200+ were spread vertically. Now they are round, even at 400yds. The biggest mistake I see Rimfire PRS shooters make re. groups not buying premium ammunition. Assuming of course that you positional group size is approaching your bench group size.
 
Mystic Precision said:
Consider putting up a target at 150, 200, 250, 300... collect the real world drop at cool temp... collect the data at hot temps. Use the app to get you on paper, use the target to determine the correct value.

do this a few times to make sure that each data set per temp repeats. now figure out the temp limits when things change.

When shooting be aware that as things warm up, your drop will change. As your impacts go higher as temps warm up, you can adjust in real time gradually between the cool and hot dope card.

Voila...

Jerry
Click to expand...
Or use a chronograph, remembering to make sure the ammunition is at ambient temperature before testing. Interpretation of 22LR groups at 200+ is very likely to lead to bad data assumptions unless your gear, ammo, wind reading, and shooting ability are already at a high level.
 
A simple experiment... at your home, chart the change in DA (density altitude) from 9am to 4pm every couple of hours. Repeat a bunch of times. how much does it vary in a single day?

Have you ever just plotted the dope generated by the app over the course of a day for a couple of distances?

Wind has been and likely always, the biggest affect we see shooting rimfire at LR. Temp affects ammo only when large swings happen in a day.. and that usually happens during the shoulder seasons... or some freak June cold front. Most times, the temp change during the day isn't that much.

wind can bounce you around a bunch from shot to shot... far more then I have ever seen due to DA change.

I know this is short range but how many shooters for ORPS use 0, 0, 0.8mils and 1.8mils for their dope? and it can vary 0.1mils higher. This with typical match ammo like SK RM, Lapua CX, Eley Match. Curious to hear from shooters using SK LRM what dope they use.

Jerry
 
Mystic Precision said:
A simple experiment... at your home, chart the change in DA (density altitude) from 9am to 4pm every couple of hours. Repeat a bunch of times. how much does it vary in a single day?

Have you ever just plotted the dope generated by the app over the course of a day for a couple of distances?

Wind has been and likely always, the biggest affect we see shooting rimfire at LR. Temp affects ammo only when large swings happen in a day.. and that usually happens during the shoulder seasons... or some freak June cold front. Most times, the temp change during the day isn't that much.

wind can bounce you around a bunch from shot to shot... far more then I have ever seen due to DA change.

I know this is short range but how many shooters for ORPS use 0, 0, 0.8mils and 1.8mils for their dope? and it can vary 0.1mils higher. This with typical match ammo like SK RM, Lapua CX, Eley Match. Curious to hear from shooters using SK LRM what dope they use.

Jerry
Click to expand...

For SK LRM at those distances, I use 0, 0, 0.7 and 1.7. The 50 yard is going to impact 0.1 high. To me it makes no difference. How many shooters can hold to within 0.1 mils on a shakey barricade. Certainly, not me.
 
Thanks for all the replies, all great information. I’m keen to collect my own data and build a drag curve model for my individual gun and Lot of ammo. I do shoot over flags (surveyors’ tape) and I have then fastened to forestry style plot markers so the swing freely. I have them placed every 50m out to 350m, one set up through the center so I can see them through my scope during shooting, and I have placed more along the edge of the area so I can predict what the edges are doing as well. I’m not sure if this technique is efficient or do I need something more sensitivity.

I do shoot more paper targets than I do steel and I do enjoy collecting data and trying to learn more when I shoot, and it helps feed my OCD. Currently I have been shooting 50, 100, 150, 200, 250 and 300m and I’m meticulous in my data collection and management and I should have a lot of data I can already use. I was wondering if there is a link or example of a data sheet and how and what you are collecting and organizing, your data in a useful sense?

I will try some slower ammo again, my rifle does like SK Rifle Match, but the one lot of Center X never shot well and would be worth another try though currently I’m happy with my select performance/price range for learning ammo. Sadly, I can’t shoot a custom RimX with X-Act but that not in the cards for me and would be a waste at my currently level of knowledge as don’t feel I have a handle on this. I do shoot over a chrono a lot and have a lot of data over different temperature/pressure regimes. I’m lucky in the sense where I shoot is very close to my home and its easy for me to shoot regularly. I’m always open ideas and I enjoy shooting with a purpose in terms of learning more, experimenting and collecting data. Yes, I agree environmentals and variation in ammunition adds another level of static and one must use caution in interpreting results.

Jerry my dope for SK Long Range Match to 100m is;

50m-0
75m-0.8
100m-1.9
MV of 1096
904hPa
24C
22inch barrel
RA4 drag curve.

Thanks again for all the help, I’m happy I’m tasked with more homework. I have to be honest, and I do enjoy shooting and learning and I’m enjoying the infancy stage of this style of shooting/learning a lot.

Take care.
 
Thanks emerson, I do use a chrono frequently. Do you keep your ammo and rifle the same temperature so there is minimal difference in climatization for the ammo to gun? I try to keep my ammo and gun the same temperature but if I'm shooting in the sun, I keep my ammo shaded, do you feel I should have both in the sun, as that temp can vary a lot. In cooler temps <10C i keep ammo and gun together so the temp is the same. On my ballistic calculator I enter both the ambient temp and powder temp and I use the same temp which essentially cancels the "consider powder temp"

I guess my question is what technique do you employ with gun and ammo in sunny hot days or am I chasing this down a rabbit hole ?
 
To the subject question, I am interested in learning other people's findings on the temperature sensitivity value.

Sadly (?) our summer has been hot and consistently hot, practically never being outside of the 19-32C temp range during shooting hours. I think to get a proper sensitivity number I need to collect data at a wider temperature range. I'd like to do 10C, 20C, and 30C.

I have done the 20C and 30C with CenterX and SKLRM and SKRM. Some days the values put into Strelok result in Strelok showing a sensitivity factor of 1.2%. Data from other days can put me at 3%.

I think 3% is too high and not repeatable, and perhaps other factors were at play. Currently I'm using 1.2%.

I wish Strelok would use proper units in its temperature sensitivity factor. A percentage, it is not. It should be in units of speed per temperature. Using some quick checks, I can tell that there is a weird formula behind the scenes at work in Strelok: 1000fps@100C, 990fps@99C is 10fps/C and Strelok shows 15.2%; 1000fps@100C, 900fps@90C is 10fps/C and Strelok shows 16.7%. Add more confusion in that when you actually generate ballistic solutions with this temp sensitivity configured, it seems to correctly compute the muzzle velocity: 100C-1000fps, 50C-500fps, 10C-100fps (but the pattern goes non-linear after 100C ??).
 
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Walterfisher said:
For SK LRM at those distances, I use 0, 0, 0.7 and 1.7. The 50 yard is going to impact 0.1 high. To me it makes no difference. How many shooters can hold to within 0.1 mils on a shakey barricade. Certainly, not me.
Click to expand...

Have you had to change that dope any time since April? I suspect you haven't... and if you surveyed other regularly attending competitors, they don't either. And I would suspect that everyone is using very similar dope numbers... SK RM/CX will be 0.1mil more vs LRM within that 100yds. And I also suspect, that these values are what shooters are using ACROSS Canada... and the US.. within 0.1mil... when temps are over 15C

My first ORPS match was in April... cool but not cold, very windy. My last match was July... stinking hot, very light winds. The cool was still warmer then when my ammo goes for a change... and the hot was still under where things over heat.

Net affect... same dope (this was at the same range FYI). Was DA different? yes... enough to matter, nope.

My bolt rifle was set up for the Westerns in Heffley Creek. July 2022 and stinking hot. I just shot it again here in July... again, stinking hot. My dope card was spot on out to 330m which was the furthest we shot that day. DAs similar...

There can be a difference in that drop profile depending on rifle, ammo and beyond 150... maybe 175yds. Definitely possible beyond 225/250yds. This trend increases as you get colder and can go for an absolute crap once go below your ammos/system operating temp... ie LR groups and dope really change enough that you are way off target or can't hit what you have been hitting during the warm climes.

The only way to know where the limits are is to test... an app will not tell you squat cause it can only assume a linear change which with rimfire may not be.

I tend to stop competing when it gets cold so I use a 'warm' temp system. Kamloops this June was a freak cold front.... 28C on Thursday, 6 to 8C Sat morning and stayed really cold all day (just watch the video.. everyone has every piece of clothing they own on them) and yes, my combo went for an absolute crapper for 1/2 of the day. When it warmed up after lunch (around 14C), things settled down and my hit rate went back to what it should be. This extreme of temp is rare especially when you are shooting in a season when heat stroke is more your concern.

But quite common in late Sept and Oct... or early spring.

Jerry
 
Mystic Precision said:
Have you had to change that dope any time since April? I suspect you haven't... and if you surveyed other regularly attending competitors, they don't either. And I would suspect that everyone is using very similar dope numbers... SK RM/CX will be 0.1mil more vs LRM within that 100yds. And I also suspect, that these values are what shooters are using ACROSS Canada... and the US.. within 0.1mil... when temps are over 15C

My first ORPS match was in April... cool but not cold, very windy. My last match was July... stinking hot, very light winds. The cool was still warmer then when my ammo goes for a change... and the hot was still under where things over heat.

Net affect... same dope (this was at the same range FYI). Was DA different? yes... enough to matter, nope.

My bolt rifle was set up for the Westerns in Heffley Creek. July 2022 and stinking hot. I just shot it again here in July... again, stinking hot. My dope card was spot on out to 330m which was the furthest we shot that day. DAs similar...

There can be a difference in that drop profile depending on rifle, ammo and beyond 150... maybe 175yds. Definitely possible beyond 225/250yds. This trend increases as you get colder and can go for an absolute crap once go below your ammos/system operating temp... ie LR groups and dope really change enough that you are way off target or can't hit what you have been hitting during the warm climes.

The only way to know where the limits are is to test... an app will not tell you squat cause it can only assume a linear change which with rimfire may not be.

I tend to stop competing when it gets cold so I use a 'warm' temp system. Kamloops this June was a freak cold front.... 28C on Thursday, 6 to 8C Sat morning and stayed really cold all day (just watch the video.. everyone has every piece of clothing they own on them) and yes, my combo went for an absolute crapper for 1/2 of the day. When it warmed up after lunch (around 14C), things settled down and my hit rate went back to what it should be. This extreme of temp is rare especially when you are shooting in a season when heat stroke is more your concern.

But quite common in late Sept and Oct... or early spring.

Jerry
Click to expand...

I don't change that DOPE at all anytime it is +10 or warmer. I do change to SK Biathlon below +10 and use similar dope though.
In my rifle, SK LRM is very temperature sensitive below +10 and starts to throw crazy fliers. So I don't use it in low temperatures.
In normal summer temperatures it works great. I have used that same dope up to +35 and there was minimal change out to 300 yards.

In another rifle that I only use Eley ammo in (Team, Match or Tenex), my dope stays the same all year from -20 to +30. That particular rifle with Eley upper tier ammo shows barely any temperature sensitivity regardless of the temperature. If it's below -20, all bets are off, crazy things start to happen with .22 ammo
 
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I will have to investigate Eley if I ever decide to compete in the cold again. Currently, I have some Lapua biathon ammo just in case.

You have a good understanding on your temp range and limits. More shooters should confirm what it is for their system... the app will not solve that.

I think shooters will be quite surprised at their dope values if they printed them out and just compared over a match or season.

Jerry
 
Ridge-Runner said:
I guess I'm new to the game and not sure what to expect in terms of ballistic calculator accuracy. I guess my core questions are;

Do you tweak your ballistic calculator frequently or do you set it and its good to go ?
Once I have trued the BC and confirmed hits to 400 yards I’ve had better results leaving things be than constantly updating during a match.

What temperature sensitivity values are you using and how did you determine those values ?
1.1% from 16C to 21C. Chrono data from various temps, entered into Strelok Pro.

Do you keep the "Consider Powder Temperature" setting on your calculator, off or on ?
Off

What drag curve model works best for you in 22lr?
I use RA4, true BC at 200 yards with a 50 yard zero. Good enough for consistent hits out to 425yards on a Full size ipsc shooting off a prop.

What do you consider acceptable accuracy from your Ballistic calculator at 300m, right on, within 1 mil, within 2mils, more mils ?
I’d consider my abilities during a match to be .5ish MIL at 300M under ideal circumstances, but the answered really is: The best possible is what I consider acceptable.

If I set my Ballistic Calculator and I test it, I find my morning cooler temps (10-14C) more accurate to line up with the calculator than I do in the afternoon when temps are 27-30C, if that helps at all ? This is where I'm wondering if my "Temperature Sensitivity Factor" is set too high ?
From 5C to 15C you’ll see the biggest swing in temp sensitivities in terms of FPS/degree C of change, you will certainly see a a variance, should be manageable if you have your data sorted.

Thanks again and I'm just trying to learn and get the most out of my shooting.
Click to expand...

Good on you for asking questions and exploring what goes into good data. Too many people take the path of least resistance, or worse over complicate this side of shooting.

Here is a great video that is worth undivided attention for those wanting to get the most from Strelok: click this
 
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Thank you so much Thewhole9yards, its very much appreciated and it clears up my questions and sends me back on the range to experiment more, the fun part!!

Thanks for sharing your knowledge and the link

Good shootin to all
 
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