I recently got a chronograph that pairs with blue tooth to a phone. In addition to using the Lotto app for checking a lottery ticket, using the phone with the chrony is the best use I have for a smartphone.
I first tested the chrony on July 11th and when calm conditions continued over most of the following week I went to the range as often as possible -- but not always to get chronograph data. The weather was remarkably similar through those days, with warm temperatures.
Reflecting on the chronograph data, I can make two tentative observations. These aren't conclusions as there isn't enough information. Furthermore, the accuracy of the chronograph hasn't been established.
1. Even in barrels of the same length, MV will vary by individual barrel.
I used two Anschutz rifles with barrels of the same length. One was a 1411, the other a 1913, and both have 69cm (27.2") barrels. The 1411 is 41 years older than the 1913. What I saw was that over a total of seven boxes of the same lot of Center X, the older rifle produced slower average MVs than the 1913.
More specifically, with the 1411 the average MV of the 198 shots that were recorded was 1031 fps. With the 1913, the average MV of the 243 shots recorded was 1063 fps. That's an average difference between two different barrels of 32 fps with the same lot of ammo. That seems significant for two barrels that are the same length.
2. As outside temperatures rise, average MV seems to rise. This is a more tentative observation than the previous because the amount of data is insufficient to draw firmer conclusions.
I don't have the temperatures recorded for each box of CX that I shot with the 1411, but I do for each box of the same ammo I shot with the 1913. (I don't know how the chrony gets the temperature.)
With the 1913, the temperatures rose from 70 to 79 degrees F (21 to 26 degrees C). During that temperature increase, the average MV of each consecutive box of the same ammo increased. The first box averaged 1053 fps, the fifth 1071 fps. Each box average was faster than the last. The same was observed in the 1411 as the morning progressed, with the first box averaging 1024 fps and the third 1035 fps.
As noted above, this is a tentative observation and my information is insufficient to draw firm conclusions.
For anyone wondering how the average MV's observed related to the average speeds recorded by Lapua for the same ammo, the lot of the CX under discussion is 28553/703486. The reported way to established how Lapua rates the average MV of its ammo is to put a "3" in front of the first two digits to get the average MV in meters/second. That would make it 328 m/s or 1076 fps. Lapua determines this average through their 66 cm test barrels.
I will post the summary data in the next two posts.
I first tested the chrony on July 11th and when calm conditions continued over most of the following week I went to the range as often as possible -- but not always to get chronograph data. The weather was remarkably similar through those days, with warm temperatures.
Reflecting on the chronograph data, I can make two tentative observations. These aren't conclusions as there isn't enough information. Furthermore, the accuracy of the chronograph hasn't been established.
1. Even in barrels of the same length, MV will vary by individual barrel.
I used two Anschutz rifles with barrels of the same length. One was a 1411, the other a 1913, and both have 69cm (27.2") barrels. The 1411 is 41 years older than the 1913. What I saw was that over a total of seven boxes of the same lot of Center X, the older rifle produced slower average MVs than the 1913.
More specifically, with the 1411 the average MV of the 198 shots that were recorded was 1031 fps. With the 1913, the average MV of the 243 shots recorded was 1063 fps. That's an average difference between two different barrels of 32 fps with the same lot of ammo. That seems significant for two barrels that are the same length.
2. As outside temperatures rise, average MV seems to rise. This is a more tentative observation than the previous because the amount of data is insufficient to draw firmer conclusions.
I don't have the temperatures recorded for each box of CX that I shot with the 1411, but I do for each box of the same ammo I shot with the 1913. (I don't know how the chrony gets the temperature.)
With the 1913, the temperatures rose from 70 to 79 degrees F (21 to 26 degrees C). During that temperature increase, the average MV of each consecutive box of the same ammo increased. The first box averaged 1053 fps, the fifth 1071 fps. Each box average was faster than the last. The same was observed in the 1411 as the morning progressed, with the first box averaging 1024 fps and the third 1035 fps.
As noted above, this is a tentative observation and my information is insufficient to draw firm conclusions.
For anyone wondering how the average MV's observed related to the average speeds recorded by Lapua for the same ammo, the lot of the CX under discussion is 28553/703486. The reported way to established how Lapua rates the average MV of its ammo is to put a "3" in front of the first two digits to get the average MV in meters/second. That would make it 328 m/s or 1076 fps. Lapua determines this average through their 66 cm test barrels.
I will post the summary data in the next two posts.
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