Temperature sensitivity

[acourvil]

Can anyone point me to any data on temperature sensitivity of Lapua rimfire ammo? I've noticed that under 50F my good lot of CenterX is less good. Today I played around with that CenterX and some Biathlon Extreme in temps just above 50F, and it looks like the CenterX slowed down 20 to 30 FPS from summer temps, while the Biatlon Extreme is currently shooting about the speed that I get in the summer with the CenterX. Is there any more comprehensive data available?

 

[USMC22]

I’ll have some more data soon here’s what I got:

 

[Jefe's Dope]

Biathlon is loaded hotter, more powder, because it's intended to shoot a lower temps. Hence the name "Biathlon". Lower temps = lower speeds. Biathlon should see similar speeds at cold temps as CX sees at warmer temps.

What do you mean by "less good". Are the groups bigger or are you just referring to speed?

 

[Jefe's Dope]

Can anyone point me to any data on temperature sensitivity of Lapua rimfire ammo? I've noticed that under 50F my good lot of CenterX is less good. Today I played around with that CenterX and some Biathlon Extreme in temps just above 50F, and it looks like the CenterX slowed down 20 to 30 FPS from summer temps, while the Biatlon Extreme is currently shooting about the speed that I get in the summer with the CenterX. Is there any more comprehensive data available?

This was posted 39 minutes ago and now shows "banned" under the username. WTF?

 

[acourvil]

Biathlon is loaded hotter, more powder, because it's intended to shoot a lower temps. Hence the name "Biathlon". Lower temps = lower speeds. Biathlon should see similar speeds at cold temps as CX sees at warmer temps.

What do you mean by "less good". Are the groups bigger or are you just referring to speed?

Both. The speed is lower and the SD is higher. At 270 yards, it went from about 1.5 MOA to about 3 MOA (more vertical spread)

 

[acourvil]

This was posted 39 minutes ago and now shows "banned" under the username. WTF?

My account was hacked a couple weeks ago and closed because of that. The “Banned” banner is a remnant waiting for correction

 

[1588]

I don't have any data, just results on target.

Last year I was zeroing my Savage MKII at 50 Meters in 34-degree weather for a New Year's Day Egg Shoot. Firing 10 shot groups, I had 7 to 8 rounds in a nice sub .400 group with low flyers 1" directly below the majority of the group. The guys on RimfireCentral told me that was not unusual for cold temps.

 

[Williwaw]

I think the BANNED banner is totally OG.

I shoot daily right down to 0F and am doing my best to hold my scores/results as near my summer results as I can. I have split my cases half to summer and half to winter to see which ammo does best and to quantify the degradation in score and resulting 40 shot aggregate group. I also bought a bunch of Biathlon Extreme to see what it can do.

So far Biathlon Extreme hasn't wowed me.

I have had to move my tuner out by a couple clicks and it looks like I'm going to be dropping 2 or 3 points in score minimum.

I keep my ammo HOT, I try to keep my rifle warm for as long as I can. Carbon rings are more of an issue. Remember that the cool air is way denser. It isn't just decreased MV but thicker fluid all the way to the target. Winds that aren't a problem in summer are impossible in the winter.

Because I only shoot 50 yards I have not come up to speed on the ballistic calculators that so many of you use. I'd really appreciate if someone could tell me the deflection of a full value 5mph wind at 70F/50 percent humidity and 10F/90percent. Also recommend an online program if you like. Thanks.

 

[USMC22]

I think the BANNED banner is totally OG.

I shoot daily right down to 0F and am doing my best to hold my scores/results as near my summer results as I can. I have split my cases half to summer and half to winter to see which ammo does best and to quantify the degradation in score and resulting 40 shot aggregate group. I also bought a bunch of Biathlon Extreme to see what it can do.

So far Biathlon Extreme hasn't wowed me.

I have had to move my tuner out by a couple clicks and it looks like I'm going to be dropping 2 or 3 points in score minimum.

I keep my ammo HOT, I try to keep my rifle warm for as long as I can. Carbon rings are more of an issue. Remember that the cool air is way denser. It isn't just decreased MV but thicker fluid all the way to the target. Winds that aren't a problem in summer are impossible in the winter.

Because I only shoot 50 yards I have not come up to speed on the ballistic calculators that so many of you use. I'd really appreciate if someone could tell me the deflection of a full value 5mph wind at 70F/50 percent humidity and 10F/90percent. Also recommend an online program if you like. Thanks.

Check out the applied ballistics mobile app.

The deflection you’re asking for you could get from the app and play with different variables to see what matters and when.

 

[Hi-NV Shooter]

I think the BANNED banner is totally OG.

I shoot daily right down to 0F and am doing my best to hold my scores/results as near my summer results as I can. I have split my cases half to summer and half to winter to see which ammo does best and to quantify the degradation in score and resulting 40 shot aggregate group. I also bought a bunch of Biathlon Extreme to see what it can do.

So far Biathlon Extreme hasn't wowed me.

I have had to move my tuner out by a couple clicks and it looks like I'm going to be dropping 2 or 3 points in score minimum.

I keep my ammo HOT, I try to keep my rifle warm for as long as I can. Carbon rings are more of an issue. Remember that the cool air is way denser. It isn't just decreased MV but thicker fluid all the way to the target. Winds that aren't a problem in summer are impossible in the winter.

Because I only shoot 50 yards I have not come up to speed on the ballistic calculators that so many of you use. I'd really appreciate if someone could tell me the deflection of a full value 5mph wind at 70F/50 percent humidity and 10F/90percent. Also recommend an online program if you like. Thanks.

Have you tried tuning in lower temperatures? I shoot in 30+-100+ degrees and have not needed to adjust my tuner settings on any rifle. I try and tune in temperatures of 45-60 by doing this I find the lower velocity due to the change in powder burn rate has little effect on POA/POI my best scores have come in temperatures below 60. only thing I see is POI change with 90+ temperatures where I have to hold lower but generally under a 1/4"
I also found that by letting the ammo acclimate to ambient temperatures it is more consistent on how it shoots this is regardless of hot or cold. if you think about how temperatures will affect burn rate which affects velocity your POI will continuously change how much will vary but will affect your accuracy. trying to keep ammo at a certain temperature as you shoot will be fruitless effort if kept cool it will warm up as you shoot keeping it warm will start to chill as you shoot. RF is about consistency having ammo change as you are shooting will be a challenge for sure.

Lee

 

[acourvil]

I just started trying to figure out how the temperature is affecting what I am shooting. I first noticed it this spring when shooting in cooler temps than I had last summer, but then it warmed up before I got a chance to do anything with it. Now that the temps have cooled, I want to do some comparisons but have had limited time. I did just run some comparisons strings at 50 yards. For me, the Biathlon Extreme seemed to work well at the lower temps, slightly better than the CenterX. This was in 2 different rifles, one with a 1:16 twist and one with a 1:9 twist. But this was only one session shooting a couple of boxes with public range distractions, so I don’t think I can draw any firm conclusions yet.

 

[Hi-NV Shooter]

I just started trying to figure out how the temperature is affecting what I am shooting. I first noticed it this spring when shooting in cooler temps than I had last summer, but then it warmed up before I got a chance to do anything with it. Now that the temps have cooled, I want to do some comparisons but have had limited time. I did just run some comparisons strings at 50 yards. For me, the Biathlon Extreme seemed to work well at the lower temps, slightly better than the CenterX. This was in 2 different rifles, one with a 1:16 twist and one with a 1:9 twist. But this was only one session shooting a couple of boxes with public range distractions, so I don’t think I can draw any firm conclusions yet.

It will really skew your results if you try and compare the ammo's performance with two different twist barrels as it is probably a given, they will shoot differently regardless of temperatures. if you are going to compare just the different twist in themselves on how they shoot in the different temps that would be ok.
I do know Lapua Biathlon Extreme shot really well in a 28" 1:16 3G barrel I tuned shot in the middle of August somewhere in Kentucky rifle agg. 2166 for 6 targets ARA.

Lee
p.s corrected the state I posted it was in Kentucky not NC

 

[acourvil]

I was comparing the CenterX to the Biathlon Xtreme in each barrel. FWIW, both barrels shoot the CenterX pretty much the same in terms of precision at 50 and 100 yards, with the 1:16 barrel maybe shooting a little better. The 1:9 barrel is also 4” longer and is slower.

One of the things I’m wondering is if the higher SD of the CenterX in lower temperatures might be partly due to differing times that the rounds are n the chamber, resulting in different temperatures when fired.

 

[obx22]

It’s been my experience that with my mid-priced crap temps effect both velocity as well as extreme spread. There seems to be a “Goldilocks” range that you get all the ammo has to offer, and above or below things start to get bad.
During matches in Jan-Feb, folks took to leaving their ammo on the dashboard in the sun. In the summer’s heat, out would come the cute little ammo coolers

 

[Hi-NV Shooter]

I was comparing the CenterX to the Biathlon Xtreme in each barrel. FWIW, both barrels shoot the CenterX pretty much the same in terms of precision at 50 and 100 yards, with the 1:16 barrel maybe shooting a little better. The 1:9 barrel is also 4” longer and is slower.

One of the things I’m wondering is if the higher SD of the CenterX in lower temperatures might be partly due to differing times that the rounds are n the chamber, resulting in different temperatures when fired.

I am not understanding what you mean by the CX being in the chamber longer or did you mean bore

Lee

 

[acourvil]

Simply that when I shoot a box of ammo, or a 6x5 or whatever, there are times when the round is in the chamber longer, i.e, I stop to write something down, a big wind gust comes up, someone shooting next to me asks a questions, etc. So some rounds might be in the chamber for just a second, some for 5 or 10 seconds. If the chamber is already warm from shooting, would think that would make a difference n the temperature of the round when fired, and that might increase the SD if the powder is temperature sensitive. Not specific to CenterX per se.

 

[Hi-NV Shooter]

Simply that when I shoot a box of ammo, or a 6x5 or whatever, there are times when the round is in the chamber longer, i.e, I stop to write something down, a big wind gust comes up, someone shooting next to me asks a questions, etc. So some rounds might be in the chamber for just a second, some for 5 or 10 seconds. If the chamber is already warm from shooting, would think that would make a difference n the temperature of the round when fired, and that might increase the SD if the powder is temperature sensitive. Not specific to CenterX per se.

Ok I understand now what you meant. I don't believe the powder is that sensitive where a couple of degrees would affect it to make a difference. during this time of the year, I have never felt my barrel get even warm no matter how fast I shoot. but for me I let my ammo sit at ambient temperatures, so it is loaded pretty much at the same temperature as the chamber/barrel. one other factor I am using a tuner so this will help with any swings in velocities up to a certain point.
one validation method I use to check a tuner setting is it has to be able to wait what is meant by this I can load a round and leave it for extended periods and the shot will not change significantly to a point where I get concerned. because I am shooting BR, I have to wait a lot of times for the condition so I can shoot. if powder burn rate from temperatures swings causes a shot to go outside my window, I am working with for hold offs I am in big trouble. scores are going to suffer.

Lee

 

[obx22]

Simply that when I shoot a box of ammo, or a 6x5 or whatever, there are times when the round is in the chamber longer, i.e, I stop to write something down, a big wind gust comes up, someone shooting next to me asks a questions, etc. So some rounds might be in the chamber for just a second, some for 5 or 10 seconds. If the chamber is already warm from shooting, would think that would make a difference n the temperature of the round when fired, and that might increase the SD if the powder is temperature sensitive. Not specific to CenterX per se.

Something you may benefit from:
When shooting your series, leave the fired case chambered and bolt locked till ready to load and fire. I’ve noticed under certain conditions, if I pull the bolt mid-string and peer into the bore, I will see water droplets as condensation forms due to the temp disparity. I believe this is part of the source of fliers in certain conditions. Keeping the breach sealed seems to alleviate this.

 

[grauhanen]

A study on External Barrel Temperature and Precision was published online in 2013 and may be of interest to some readers.
See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3944560/

 

[Hi-NV Shooter]

Something you may benefit from:
When shooting your series, leave the fired case chambered and bolt locked till ready to load and fire. I’ve noticed under certain conditions, if I pull the bolt mid-string and peer into the bore, I will see water droplets as condensation forms due to the temp disparity. I believe this is part of the source of fliers in certain conditions. Keeping the breach sealed seems to alleviate this.

Interesting why do you think the condensation doesn't form if you leave a fired case in the chamber?
Bill Calfee had what he called a water bore test I believe it was to see if the tuner was set correctly. if you fired a shot and waited then cracked open the bolt enough to unseal the fired case and then closed and waited a minute or two then extracted and loaded and fired a shot the shot should go to the same POA as the prior shot. in this case the condensation was nullified by the correct tuner setting.

Lee

 

[Dstoenner]

For what it is worth, i have found R50 to be the best low temp 22lr. The worst has been Eley. The others are just in between.

David

 

[Hi-NV Shooter]

For what it is worth, i have found R50 to be the best low temp 22lr. The worst has been Eley. The others are just in between.

David

I think with Eley it is the type of lube. Lapua and RWS is similar from what I can remember. I been getting great results with Lapua

Lee

 

[JG26_Irish]

A recent observation is the amount of drop with 27 spd Center X when shot at 200y in 84deg F and 52 deg F. In the warm weather it was 8.4 mil and yesterday in the cooler temps the drop was 9.2 mil. A slight wind in the cooler air was very impactful causing the rounds to spread 4” horizontally at times. Plus the Lapua lube gets harder below 50 deg. I have a few rifles that shoot Lapua biathlon extreme well. It is faster and has no lube on the cases at all which makes it stick in some tight match chambers. The bullet lube is either harder or non existent. If I recall, Lapua told me they did not lube that product but it caused so many issues that they discontinued it.

 

[grauhanen]

I have a few rifles that shoot Lapua biathlon extreme well. It is faster and has no lube on the cases at all which makes it stick in some tight match chambers. The bullet lube is either harder or non existent. If I recall, Lapua told me they did not lube that product but it caused so many issues that they discontinued it.

Neither standard rifle match ammo (e.g. Lapua, Eley, RWS) nor biathlon ammo have lube on the cases. Any lube used specifically in case manufacture is washed off. All, however, have lube on the bullets.

 

[acourvil]

A recent observation is the amount of drop with 27 spd Center X when shot at 200y in 84deg F and 52 deg F. In the warm weather it was 8.4 mil and yesterday in the cooler temps the drop was 9.2 mil. A slight wind in the cooler air was very impactful causing the rounds to spread 4” horizontally at times. Plus the Lapua lube gets harder below 50 deg.

When I play with the numbers, that looks like about a 50 fps difference. I think I am seeing a bit more than that, but in the same neighborhood.

 

[JG26_Irish]

When I play with the numbers, that looks like about a 50 fps difference. I think I am seeing a bit more than that, but in the same neighborhood.

I wish I had the chrono data to share but do not. I think the two main variables are the velocity change and the air density altitude. My altitude was about 850 at that range.