What Does BBL Length Do?

gars320

October 24, 2002 17:39

I need advice from the experts. What does a shorter bbl length meen for a rifle? Specificly I have a NIB Savage 10FP with Hvy 20" bbl. I am wondering what is the actual difference in performance, all things being equal, same ammo, same scope, same day, between the 20" bbl and the 24" or 26"? What is the difference in velocity, distance, enery etc? If it is too great a difference would I be better off looking to trade it out, or just have it rebarreled to a 24 or 26 inch length? If so which would be the best barrel to have installed?
Thanks for all answers

Nil Illegitimus Carborundum

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  gskyhawk

  October 24, 2002 18:10

  gars: I think people are going to want to know what cal. your rifle is and what you are using it for,
  we had a rem. in 223 that we had shorten 4 inches and it lost about 200 fps. general rule is about 50 fps loss per inch with a shorter barrel

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  gars320

  October 25, 2002 14:22

  Oops!!! I forgot It's a Savage 10FP in .308 caliber with a 20 inch heavy bbl. 12x Unertl scope, bedded, free floated, will be using either Federal Match Grade ammo or Miltary 7.62mm Ball ammunition. I will probably never use it in excess of 600 yards and more likely 300 yards or less. Most likely use will be target shooting on a known distance type range.
  Thanks for taking the time to reply.
  
  Nil Illegitimus Carborundum
  
  Edited by - GARS320 on 10/25/2002 18:26:29

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  mark christian

  October 25, 2002 14:58

  gars320, This is copied straight from an exterior ballistics table: velocities by barrel length- .30 cal, 150 FMJ-BT (this would be your military ball ammo) Actual 15' velocity from 24" barrel- 2905 fps., 22" barrel- 2865 fps., 20" barrel- 2830 fps. Rifle energy by barrel length for identical load: 24"-2810 fp, 22"- 2735 fp, 20"- 2670 fp. as you can see the differences are not huge- perhaps 5%, but they are there. How much are you willing to spend for such a small gain?
  
  Keep in mind that the .308 Winchester is a simple commercial loading of the 7.62X51 NATO round and that cartridge was designed for use by our post war military. Barrel lengths for the planned M14 rifle and the M60 machinegun were either below or right at the 26" length. Since the cartridge would not be used in barrels over that length, there was little need to build in "extra" performance for use in longer barrels.
  
  Once you get beyond a certain barrel length, the cartridge has expended all of its potentional and the extra inches of barrel simply cause drag and actually cause the bullet to drop in velocity.
  
  Mark T. Christian

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