So I decided to try BM11 rimfire challenge today in the cold to see if I could learn anything. I have been waiting for a nice calm but cold day to try this so I could just see the effect on accuracy not my ability (or lack there of) to read wind. I just copied this from my post in the rimfire challenge thread so sorry if you have already read this. If you don't know about that thread it is 6 groups of 5 rounds shot prone at 50, 100, and 200 yards for size. If you have not already tried it out go shoot it, its a good course of fire and requires a lot of concentration to shoot it all the way through in one session.
It was 15f with little wind, clear and sunny (but dropping fast, damn Maine winter...). I shot Center X at 50 yards and Center X and also Lapua Ploar Biathlon at 100 yards and Center X and Polar at 230 yards (I decided to shoot as far as I could to see most dramatic effect the cold has on these rimfires). Here are the results:
50 yards
100 yards (I shot 2 extra groups just because using a 1/2 mil hold below the target above the 2 extra groups, but I circled them and didn't include them in the average)
230 yards (left to right & top to bottom) : 5.050", 3.809", 2.460", 3.825", 3.128", 3.703"
* the 2 groups to the right that were high were the Polar Biathlon*
Average for 50yds = 0.369"
100yds = 0.936"
230yds = 3.663"
So what did this tell me? First I noticed flyers that I usually don't get with this rifle & ammo combination, they were sporadic and not called. Every shot felt pretty good, however the flyers could of been me after all I was shooting with 2 pair of gloves on (liner and a heaver over glove) and my bipod was on glare ice which made things interesting to say the least. I did put a towel down for the bipod to sit on which usually gives me a bit more grip but this ice wanted no part of that, it was just plain slick!! I also had been chowing on some high sugar foods and plenty of java just a few hours prior so some of this could of been me.
It is easy to tell that the accuracy was not as good as it usually is for this rifle & ammo combo in the warmer weather. But with that being said I was pleasantly surprised with the way it shot considering the temp. As far as the Center X vs Polar Biathlon in cold weather. I just don't see the justification in the 50% or more increase in cost at least not for my Sauer. I also noticed the Polar sounded louder than the Center X but saw no major POI shift at 100 yards, however at 230 yards the POI was 4" to 4.5" higher than the Center X (see the two groups to the right). The Polar also seemed to have much more lube on the bullets than the Center X. I have shot it in the warmer air and never noticed any difference but today the Polar was sticking in the blue plastic trays that they are packaged in. I also felt them chamber and extract just a little harder, but not much. I probably would not have noticed it with any other rifle but the Sauer's bolt just runs that smooth.
As far as bullet velocity in the cold I didn't bother to chronograph the ammo but the drop was consistent with the warm weather. I had 1.9 - 2 mil from 50yds to 100yds and 9.5 - 9.7 mil from 50yds to 230yds. Keep in mind the Sauer has a 26" barrel and therefore drops a bit more than your standard 18" rimfire barrel.
Here are a few pics from today to show the ice I was dealing with:
the 230 yard berm is at the most distant tree line, you can also see the 100yd berm with the old target set up in the center
So that was what I found today in the cold. I plan on shooting more when I get a chance, hopefully in colder weather but with out wind as that really kills what I am trying to see. Usually here in Maine during the winter the cold comes with wind, there are not too many still days to see how the cold really effects a rimfires accuracy. I look forward to hearing from others in what they find while shooting rimfire in the freezer.
It was 15f with little wind, clear and sunny (but dropping fast, damn Maine winter...). I shot Center X at 50 yards and Center X and also Lapua Ploar Biathlon at 100 yards and Center X and Polar at 230 yards (I decided to shoot as far as I could to see most dramatic effect the cold has on these rimfires). Here are the results:
50 yards
100 yards (I shot 2 extra groups just because using a 1/2 mil hold below the target above the 2 extra groups, but I circled them and didn't include them in the average)
230 yards (left to right & top to bottom) : 5.050", 3.809", 2.460", 3.825", 3.128", 3.703"
* the 2 groups to the right that were high were the Polar Biathlon*
Average for 50yds = 0.369"
100yds = 0.936"
230yds = 3.663"
So what did this tell me? First I noticed flyers that I usually don't get with this rifle & ammo combination, they were sporadic and not called. Every shot felt pretty good, however the flyers could of been me after all I was shooting with 2 pair of gloves on (liner and a heaver over glove) and my bipod was on glare ice which made things interesting to say the least. I did put a towel down for the bipod to sit on which usually gives me a bit more grip but this ice wanted no part of that, it was just plain slick!! I also had been chowing on some high sugar foods and plenty of java just a few hours prior so some of this could of been me.
It is easy to tell that the accuracy was not as good as it usually is for this rifle & ammo combo in the warmer weather. But with that being said I was pleasantly surprised with the way it shot considering the temp. As far as the Center X vs Polar Biathlon in cold weather. I just don't see the justification in the 50% or more increase in cost at least not for my Sauer. I also noticed the Polar sounded louder than the Center X but saw no major POI shift at 100 yards, however at 230 yards the POI was 4" to 4.5" higher than the Center X (see the two groups to the right). The Polar also seemed to have much more lube on the bullets than the Center X. I have shot it in the warmer air and never noticed any difference but today the Polar was sticking in the blue plastic trays that they are packaged in. I also felt them chamber and extract just a little harder, but not much. I probably would not have noticed it with any other rifle but the Sauer's bolt just runs that smooth.
As far as bullet velocity in the cold I didn't bother to chronograph the ammo but the drop was consistent with the warm weather. I had 1.9 - 2 mil from 50yds to 100yds and 9.5 - 9.7 mil from 50yds to 230yds. Keep in mind the Sauer has a 26" barrel and therefore drops a bit more than your standard 18" rimfire barrel.
Here are a few pics from today to show the ice I was dealing with:
the 230 yard berm is at the most distant tree line, you can also see the 100yd berm with the old target set up in the center
So that was what I found today in the cold. I plan on shooting more when I get a chance, hopefully in colder weather but with out wind as that really kills what I am trying to see. Usually here in Maine during the winter the cold comes with wind, there are not too many still days to see how the cold really effects a rimfires accuracy. I look forward to hearing from others in what they find while shooting rimfire in the freezer.