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  1. #1

    Default Twist rate and bullet weight

    Good evening
    I purchased a 7.62 k98 Mauser 24" barrel...sure it an Israeli...the license says its a Browning.
    I have not a clue about the barrel twist on this rifle and cant test it as i dont have it yet.
    Ye olde interwebs spat out different twist rates of 1/10, 1/11, 1/12 and 1/14.
    Now i am new to all this technical talk and used to pick up my dads rifle, go to the bush and shoot something.
    Going to be a first time owner i feel compelled to get a bit anal about everything regarding this weapon to get it perfect

    Whas hoping to shoot 180gn but at what twist rate would i need to be to achieve that? 180gn because i want to shoot everything i can afford with this one rifle

  2. #2

    Default

    Sorry if i posted this in the wrong subforum

  3. #3
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    Default Re: Twist rate and bullet weight

    Take a cleaning rod and brush. Take some masking tape and make a "flag" near the handle of the rod. Push the rod into the barrel until the brush is all the way into the barrel. Make a Mark on the rod at a reference point. Push the rod down the barrel making sure that the rod is turning with the rifling. Once the flag you have made has made one full rotation, make another Mark on the rod at the same reference point. Once you remove the rod measure the distance between the two marks you've made. Should be anywhere between 10 to 12 inches. 1/12 should work fine with any 180grain bullet that does not have a boat tail. 1/10 twist will stabilise pretty much any .30 bullet out there.

  4. #4
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    Default Re: Twist rate and bullet weight

    1:12 Stabilizes a 180gr soft point boat tail just fine. But if your hunting is going to be at a max of 200m, boat tail or flat base makes no difference anyway.

  5. #5

    Default Re: Twist rate and bullet weight

    Why max 200m?
    Bullet drop shouldn't be that big a deal as you can compensate or turn the windage knob to get to where you want
    Would the velocity be to low to make a humane kill past 200m?.....i have hunted with a 7x57 shooting 180gn past two hundred without a glitch, once dropping a jackal at almost 300m...maybe it was luck??
    Like i said earlier i am a total newb when it comes to the technical side of firearms
    I realy do not want to drop bullet weight below say 168gn...will mostly be hunting in the bush so distances are not that vast

  6. #6
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    Default Re: Twist rate and bullet weight

    Quote Originally Posted by Blink Stefaans View Post
    Bullet drop shouldn't be that big a deal as you can compensate or turn the windage knob to get to where you want
    Yeah, about that..........
    "It's not the dying part that scares me, it's the not living."

  7. #7
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    Default Re: Twist rate and bullet weight

    Measure your barrel's twist rate. My guess would be 1:12, as that's pretty standard, but I have seen others. Just today a friend found out his Musgrave 308W has a 1:14 barrel.

    Once you know the twist rate, you can use one of the online calculators to determine the suitability of any bullet to your rifle and location. You need a faster twist rate at sea level than on the Highveld, since the air density differs.

    Then you shoot it and see what your rifle likes. Most rifles have their personal preferences. This might not always correspond to what your calculations say.

  8. #8
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    Default Re: Twist rate and bullet weight

    I said 200m because up to there (and perhaps even a little bit further) the difference in BC between flat base and boat tail bullets won't make any measureable difference. So if you are worried about stability of 180gr bullets (or let's say for instance you measure the twist and it comes out as 1:14, which is probably marginal for most 180gr boat tails) you may as well just use flat base bullets (something like the Hornady 180gr Spitser). If you're hunting in the bush that's going to be a LONG shot...

  9. #9

    Default Re: Twist rate and bullet weight

    Looks like i am going to have to study balistic abreviations.
    What i thought was a straight forward question turned out to be HG.
    I didnt think the tail shape would make that big a difference. Is that because of the contact surface with the rifeling?
    I know a lot of you guys spend some serious dough on your cartridges, buying expensive bullets and cases ect.
    I am thinking of reloading with "Piet Maak Patrone" bullets and brass

  10. #10
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    Default Re: Twist rate and bullet weight

    Load 180ge PMP Pro-Amms to an accurate load (probably going to be around 2450fps...) and go hunt :-)

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