Speed variations in barrels

Discussion in 'Long Range Hunting & Shooting' started by Big10hunter, Oct 22, 2018.

  1. Big10hunter

    Big10hunter Member

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    Just had a custom rifle built, 300 win. The speeds I am getting are slower than what was expected from the caliber and barrel length. It is accurate, but I have read the speed can increase after 100 rounds or so. Is this true? If so, how much?

    I have friends with the same builds, and they are getting faster speeds with less powder ( some 2g less with 50 fps more speed). I don't know enough about barrels/builds to understand these two anomalies. Can anyone explain?
     
  2. J E Custom

    J E Custom Well-Known Member

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    As a barrel breaks in It normally gets faster by some amount depending on the barrel make and the finish quality.

    I do barrel break in on all of my rifles so that I reach the optimum velocity as soon as the barrel can.

    I recently did a test during break in, and the results are in this thread.
    https://www.longrangehunting.com/forums/rifles-bullets-barrels-ballistics.19/

    This may help answer your questions.

    J E CUSTOM
     
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  3. WildRose

    WildRose Well-Known Member

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    Pretty well covers it.

    The reason for that is if you do the break in process you are lapping off the remaining raised spots and filling in the low spots thus reducing friction.
     
  4. Big10hunter

    Big10hunter Member

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    What the title in the forum?
     
  5. KyCarl

    KyCarl Well-Known Member

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    I think who made the barrel has a lot to do with it?
    My 300 shoots about 100-125 FPS faster than my best friends with the exact same ammo! The barrels are both 26" the outside profiles are not the same but that shouldn't matter on speed? His is a sporter and mine is a MTU 5R.
     
    Last edited: Oct 23, 2018
  6. J E Custom

    J E Custom Well-Known Member

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    Barrel break in By len. Click on link and go to post# 20.

    J E CUSTOM
     
  7. Alex Wheeler

    Alex Wheeler Well-Known Member

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    Barrels do usually speed up in the first 200 rounds, but they do not usually let you get to a higher speed. So your max velocity will likely stay the same but you will need to back off the powder charge as the barrel speeds up. A large portion of competitive shooters will not even start load development until theres 100 rounds on the barrel.
     
  8. Deviant

    Deviant Well-Known Member

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    From my experience they speed up anywhere between 20-80 fps. I broke in a new 6.5 creedmoor Proof research barrel last weekend and it started at 2642 fps average and after about 40 rounds it was averaging 2675. I clean after every round for the first 10 shots then use copper solvent and JB bore paste and clean every 5 rounds until I hit 40 then more solvent and bore paste and keep on shooting and cleaning every 5 rounds. I dont start ladder testing or load development until after I get 100 rounds down the pipe.

    Al
     
  9. WildRose

    WildRose Well-Known Member

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    That's generally my experience with good barrels but with mass produced factory barrels you never know just because they are not handlapped and dont' have the same level of QC requirements that the small shops and custom mfg's have.