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"Bad Joke Friday" Dan (moderator emeritus)
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Discussion Starter #1 (Edited)
About a year ago I ran across an article on the AccurateReloading web site that addressed a question we see asked frequently, “What is the impact on velocity and accuracy when a rifle barrel is shortened?” This article contained excellent data that offered the reader the opportunity “cut and paste” the data from the article into a spreadsheet for analysis, which I did. As a Thompson Contender .223 shooter, I found the results to be very interesting, particularly the impact on accuracy….it got better!

Rather than post the significant amount of data involved, I’ve reduced the results to an Excel graph, crude little devil, but it takes up a lot less room! The following comment represents the background given in the web site article:

“We started off with a brand new Sako S 491 rifle with a 22-inch barrel. A B&L 6-24X scope was installed in Sako mounts. We used Federal brass and Federal 205M primers in all the following loads. Brawand 52 grain bullets, molly coated were also used. All groups are 5 shots at 100 yards.”

I contacted Saeed (AccurateReloading) for permission to use the article’s data for this post and he was very gracious in his response. The original article is located at “http://www.accuratereloading.com/223sb.html”

You will note from the graphs that the rifle barrel was shortened, inch by inch, to a final length of 10 inches. Three different powders, H4198, H322, WN135 were used. The particular point of interest that caught my eye was each of the three powders demonstrated their best accuracy at the same length, and that it was at the relatively short length of 15 inches! The unit of measure on the Y axis (accuracy) is in .1 inch increments. (And yes, I know the Y axis title misspells the word accuracy (accurach))

The velocity decrease from the 22 inch barrel to the 10 inch barrel length averaged 45 fps reduction per inch, which fits other tests I’ve read. The velocity decrease from the 22 inch barrel to the most accurate length of 15 inches averaged 279 fps (extreme spread for the three powders was 17 fps). Maybe I’m a little prejudiced, but the 15 inch barrel appears to be a very attractive option considering the accuracy performance and “less than major” reduction in velocity.
 

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Hmmm. Interesting.
Mark
 

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Beartooth Regular
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I'm sure velocity would decrease at differing rates for different cartridges (although probably in as a linear function provided you didn't start with a super long barrel for any given cartridge), but the accuracy may be a case of "barrel tuning" and I would think that any given barrel (even on the same action) may react a bit differently. Very interesting report and I'm glad Saeed was able to put it together and publish his results.
 
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