Sneak Peak at Lapua LR and SLR ammo

Walterfisher said:
As you have indicated the top row is testing of match ammo. In every instance, the muzzle velocity is greater at 18.75" than at 24.75".
Of the 10 ammos test, fully 8 of the ammos have a greater muzzle velocity at 18.75" than at 24.75".

In general, longer barrels using 22LR ammo, result in lower muzzle velocities.
Click to expand...

Walter, for goodness sake, take a break. You continue to take issue with the idea that there isn't a consistent relationship between barrel length and MV. It's not clear why. Unfortunately, the basis for your disagreement has become weaker with each of your posts.

Your observation about MVs in the top row only all being faster at 18.75" than at 24.75" is indeed correct. What's more significant, however, is that it's obvious this relationship doesn't hold consistently at the other barrel lengths. In other words, there isn't a consistent relationship between barrel length an MV.

Perhaps if you have new information that will enhance readers understanding of the relationship between .22LR MV and barrel length, you will direct readers to it. In its absence, this discussion should discontinue.
 
I don't have a horse in this race. But when I saw the tabular data source potentially available, I went to have a look thinking it would be nice to see it in a graph. The data is posted as text in the discussion forum on THE ACCURATERELOADING.COM RIMFIRE FORUM http://forums.accuratereloading.com/eve/forums/a/tpc/f/8711043/m/4871072832/p/2

I copy-pasted it into Excel and used the parsing tool (Text to Columns) to make a data chart that I could then graph.
Below is the same data Grauhanen posted above, displayed in graph form for each ammo type. This is not a statistical analysis, it is simply a visual aid for the raw data. Please note that the data are the points. The lines are simply a visual aid to see and compare. The lines are not data, and are not trend lines. For true trend lines one would need some sophisticated statistics.

If someone would like the this parsed data set in Excel to run some stats on, send me a PM and I can send it to you.
I am not a stats guy and I don't know what particular stats to run on this which can produce a definitive answer.

Have a look and see what you think for trends, for what the velocity is doing with barrel length.

Rimfire_Velocity_with_Barrel_Length-01.jpg

Note: The X axis values along the top row of the chart are the barrel lengths in inches. The axis label gets clipped off in Excel and shoved to the bottom (for some unknown reason) when the tabular data is displayed under the graph.
 

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What's also missing from the above data is the ES and SD for each mean velocity per ammo brand per barrel length. Depending on those stats, there could be big error bars plus and minus above and below each velocity point, producing a fuzzy horizontal band, not a distinct trend line.

Means (averages) could be misleading without the ES and/or SD bar to go with each point on that graph.
 
Those chart lines should be smooth curves. The up-and-down zigzags suggest a combination of ES plus not having a statistically significant number of rounds at each data point, so that an extra fast or slow round or two is capable of tenting the line.

If anything, this chart makes me love ammo that has a near-dead-flat line on it more!
 
Biologist, thanks for the visual aid in the form of the graph.
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There should be no doubt that the results of the testing with the progressively shortened Brno barrel is not conclusive. Conclusive results are the product of testing with sample sizes that aree far larger than those used by most typical .22LR ammo testers. For obvious practical purposes, of course, most testing by average shooters is rather limited.

In the case of the Brno barrel testing referred to above, there are many areas for error and about which we know nothing. These include sample sizes, chronograph accuracy throughout testing, irregular chronograph results due to fouling inconsistencies in the bore (especially first shots after fouling hardens during periods without use), irregular ammo variation from box-to-box (which is more likely especially in entry level match ammos), changes in ammo lots, and possible changes in temperature during the testing period.

If nothing else, the test with the Brno illustrates that nothing is as simple as it often is made to appear, especially on the internet forums where the idea that shorter barrels are faster than longer ones is accepted as the gospel truth -- if not in all cases, then in those that are not exceptions.;)
 
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