100 yard ammo test

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fljp2002

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Spent a few hours on range today. Tested 6 different lot.

Interesting to see that the cheapest ammo (SK Magazine) did just as good as the SK Match. Best today was SK std and Eley Force. Starting to think that SK ammo and others don't like the cold.

image by fljp, on Flickr

Rimfire coaster is 4inch. CZ 455 canadian with sporter barrel, bipod and rear bag
 
fljp2002 said:
Spent a few hours on range today. Tested 6 different lot.

Interesting to see that the cheapest ammo (SK Magazine) did just as good as the SK Match. Best today was SK std and Eley Force. Starting to think that SK ammo and others don't like the cold.

image by fljp, on Flickr

Rimfire coaster is 4inch. CZ 455 canadian with sporter barrel, bipod and rear bag
Click to expand...

It's good to see the results of such tests.

The SK Flatnose Basic target shows 15 rounds. How many in each of the other targets? You suggest that the cold temperature was a factor. It probably was. What was the temp?

A few more questions:

Do you think if you repeated the test of the six different varieties of each ammo that the results would be the same?
Do you think if you used different lots of each ammo the results would be similar?
 
Every tgt was 25rds except for Flatnose (only had 15 left).
-1 to 3c with small headwind was warming up due to the sun
I assume same lot would result about the same, different lot would be a different matter
 
Mystic Precision said:
As rule, rimfire match ammo doesn't like being below 10C.
Click to expand...

I shot the 1/4" challenge at 2 degrees C with RWS R-50. Rather than keep the ammo in my pocket or in a cooler with a hot pack etc... I just let it acclimate to ambient temperature. I don't believe temperature has a significant effect on the inherent accuracy potential of an ammo.

The question of "why does this ammo shoot well when it is warm, but not when it is cold"? Is perhaps best answered by the interplay of chemistry and barrel vibrations/harmonics. What effect does cold have on chemical reactions? They are retarded. This changes the pressure curve, muzzle velocity attained, and barrel time of the projectile. The barrel does not vibrate the same as it would with the round fired in warmer weather, and the projectile does not exit the muzzle at the same time in the barrels vibration cycle. Given rimfire rifle sensitivity to ammo, there is a clear correlation to temperature having enough effect on the combustion properties of a load so as to render it unsuitable for a particular rifle outside of a given range of temperature. Centerfire shooters who handload can confirm they require different loads for hot and cold weather.

But, does this mean that the ammo is incapable of accuracy due to cold? I would argue not, the ammo is still capable of accuracy, it'll just require a different rifle that "likes" it in the cold, or the use of a tuner will mitigate the effects of temperature.
 
Because we can't adjust the load in rimfire ammo, and the vast majority of rimfire rifles do not have tuners, the effects of reg rimfire ammo in the cold is very apparent. Match ammo is more sensitive vs HV ammo.. but then bulk HV ammo rarely shoots as well hot or cold so....

Biathlon ammo is 'hotter' ammo and typically brings the ammo back into warm weather tune. It is easy enough to test and the results are very obvious. For those interested, I have done enough testing to have some idea of where to direct you if you have a preferred SK or Lapua ammo in the heat.

worst was competing in the fall with temps bouncing all over the place. Warmed up enough for the biathlon to go 'off'... then cooled off too much for the reg stuff. Made for a challenging match.

So we are back to the original statement.... if your rifle enjoys reg match ammo in the heat, it may shoot it like crap in the cold. don't dispair, it will shoot great again when the weather warms up.

Really simple way to confirm... if ammo shot well when warm and lousy when cold... keep the ammo hot and shoot it before it cools. In really cold temps, you may see a degrade of accuracy as the ammo cools

I did it with the cold and biathlon ammo.... chilled all the ammo and it shot great. Let it warm up and it went out of tune,. Some combos are more sensitive to others and a tuner may help you tune it out???

rimfire ammo is temp sensitive...

Jerry
 
fljp2002 said:
Spent a few hours on range today. Tested 6 different lot.

Interesting to see that the cheapest ammo (SK Magazine) did just as good as the SK Match. Best today was SK std and Eley Force. Starting to think that SK ammo and others don't like the cold.

image by fljp, on Flickr

Rimfire coaster is 4inch. CZ 455 canadian with sporter barrel, bipod and rear bag
Click to expand...


I’m confused by all the holes outside the circle... are they not part of the group?
 
fljp2002 said:
They are part, but with 25 rds in cold weather you get flyers so I excluded them from the measurement and measured where the bulk of the rounds ended up
Click to expand...

But... it sounds like the purpose of this comparison was to look at “cold weather” performance... Shouldn’t you compare the “raw” results? (I’m not trying to rag on you or anything - I’m sure it’s much better shooting than I could muster. I just bring it up for the sake of comparing apples to apples when evaluating the ammo)
 
kodiakjack said:
But... it sounds like the purpose of this comparison was to look at “cold weather” performance... Shouldn’t you compare the “raw” results? (I’m not trying to rag on you or anything - I’m sure it’s much better shooting than I could muster. I just bring it up for the sake of comparing apples to apples when evaluating the ammo)
Click to expand...

Yes; a better comparison would be to find the geometric center of the entire group; then sue one size circle, and count the number of shots within the circle. If fliers were expected, then the extreme spread based on the center of the group is important. Granted, the fliers could be the shooter, the rifle, the ammo, or environmental factors. Best test would be with a rifle clamped in a rigid vise. That would remove the shooter variable.
 
All had flyers, since I shoot ORPS mainly and target are 1-4 inch in size I looked for the largest group concentration of rounds and drew the circle around that. As you can see, I only excluded 3 to 5 rounds. Reason being is that flyers will occur in competition as well so whichever ammo get me the bulk of rounds closer I would go with that ammo to improve my chances. If I was to measure actual group the result will be so close between types that selecting a a type would be next to impossible.
 
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