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Old July 13, 2009, 09:08 AM   #7
pilothunter
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Join Date: February 12, 2009
Location: Tn
Posts: 400
In like rifles the difference in trajectory between the .270 and .308, both shooting 150gr bullets is less than 15yds figuring MPBR; 287 vs 275yds for the .308. They are not as different as many would believe. If most all your shots are 250 yds or less, it's pretty much a moot point, IMO. The .308 will be slightly shorter and lighter in like rifles, due to it being a S/A vs L/A for the .270. They are both excellent cartridges that I use often and interchangeably for any deer hunting I do. I doubt you, or any deer would be able to see any big difference in performance inside 350 yds.

A link to a chart showing velocity loss in 2" increments:
http://www.loadammo.com/Topics/October05.htm



Here is a quote from an article found on Guns and Shooting Online by Chuck Hawks reference relative velocity loss for several popular calibers.
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For standard high intensity cartridges in the same test, the Lyman technicians chronographed the cartridges in barrel lengths ranging in length from 24 inches down to 20 inches with the following results:

The average loss for the .270 Win./130 grain bullet was 37 fps per inch.
The average loss for the .270 Win./150 grain bullet was 32 fps per inch.
The average loss for the .300 Sav./180 grain bullet was 17 fps per inch.
The average loss for the .30-06/180 grain bullet was 15 fps per inch.
The average loss for the .35 Rem./200 grain bullet was 11 fps per inch.

After a bunch of disclaimers, the Lyman people concluded, "The rule of thumb is that high speed, high pressure cartridges shed more speed in short barrels than do the low speed, large bore types." It's funny, but that is what I had suspected all along! ************

Last edited by pilothunter; July 13, 2009 at 02:07 PM.
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