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Question about custom barrels

laylandad
I am thinking about getting two rifles rebarreled. I have decided on Pac-Nor for the rebarrel. I am rebarreling a Remington 700 in .308 and a Winchester 70 in 7mm Rem Mag. My question is what is a good rate of twist for the .308 if I am shooting 168-175 gr pills and how many grooves should I go with and what length barrel? The same question for the 7mmRM to shoot 140-160 gr pills? Thanks for any help!
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Comments

5 comments

Date Votes
  • cpermd
    Ask Pac Nor

    CP
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  • 1KYDSTR
    I agree; you are going to one of the best companies out there so they should be able to reccomend an ideal twist, plus they may only provide barrels in that caliber in a specific twist anyway. If I were doing it myself and had the choice? 1 in "9 in 5 groove with a "26 inch tube for the 308 and about the same for the Rem Mag. ...not a big fan of the new short barreled tactical rifles...too much velocity loss for my tastes. Any faster than one in nine and I see throat erosion issues rearing their head. Also, not sure what style rifle you wish to build or what contour you wish...tactical, hunting, target etc.
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  • Hawk Carse
    My Pac-Nor .308 is a three groove 10" twist for 175 gr SMK. Length is 28" which is the longest they make without charging extra per inch.

    One source said three grooves were more durable because of the wider lands. Another recommended an 11" twist like an M14 Match but they did not offer odd number twists in three groove barrels, so I played it safe. My next will probably be a 12" twist.
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  • laylandad
    Thanks for the responses.

    The 308 is a 700 VLS. I want to maintain the same barrel contour and have better accuracy. I am going with the super match chamber and 5 groove barrel. I am still not sure about the twist rate or if I should go with a 26" or 28" barrel. What is the advantage of using the 9" vs. 10" or 12" that I see on most "Varmint or Tactical" rifles? I will be using this rifle to shoot targets and hunt with.

    On the 7mmRM, it is a sporter weight barrel, and I want to go with a similar but more meaty barrel. I think it is the #3 sporter and match chamber with 28" 1-9" barrel. This will be a dedicated hunting rifle.

    Hawk,

    What velocity are you getting from the 28" tube?
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  • nononsense
    laylandad,

    The standard twist rate for target/tactical .308 Win. rifles is 1:12" when limited to the 175 gr. VLD bullets. The 1:10" twist rate will stabilize bullet weights all the way up to 220 grains. Many of the shooters I work with ask for the Bartlein 1:11.25" - 5R barrels for their .308 rifles.

    7mm rifles often use a standard 1:9" twist rate when hunting is the primary goal. This will stabilize all of the hunting bullet weights. The 160 grain Nosler Partition at book velocities for the 7mm Rem Mag. only needs a 1:12" twist rate.

    I have always been a big supporter of long and longer barrels. However, there can be some mollifying of this concept when it applies to hunting standards. If I'm hunting out west where distances can run longer than the woods shots back east, I always opt for a longer barrel. But shorter barrels seem to work better with the woods restrictions. My point is to spend some time thinking through the circumstances under which you'll be using these rifles and then decide on the length. As I've stated before, we are now campaigning 18 - 20" barrels for shooting .308 Win. out to 1,000 yards. Yes, the noise is brighter and louder but these rifles are usually equipped with suppressors.

    Best.
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