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Will I lose too much velocity with a 7.62x51 out of a 20" barrel for a 600 yard gun?

Discussion in 'Rifle Country' started by jlbraun, Sep 26, 2007.

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  1. jlbraun

    jlbraun Member

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    Basically, I was looking at a Remington PTR in .308, and it has a 20" bull barrel.

    Is this a good 600 yard .308 gun? What barrel length / twist would be good for this application?

    Additionally, what is considered "long distance" with a .308 and what does it take to get there?

    Thanks in advance!
     
  2. Jim Watson

    Jim Watson Member

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    Well, there have been a lot of 22" M1A/M14s shot at 600 yards and you could up the load a little in a bolt action, so it would probably do.

    But Remington makes similar guns with 24-26 inch barrels and you would get some free velocity and less blast. I think the point of those short heavy barrels is for SWAT cops to carry in their trunks, they do not really shoot at what a target shooter would call long range.

    A well managed .308 is a thousand yard rifle. 1200 if you live in England and some of the rest of the Commonwealth. But it takes a long barrel on a strong action and heavily loaded ammo.

    Me?
    I've got a 28" on a Savage action. My usual load is a 175 gr Sierra MK and a stout load of Varget. A little hotter than what Black Hills sells, but the friend who got me into this keeps some BH in reserve in case he gets caught short on the handloading.
     
  3. W.E.G.

    W.E.G. Member

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    A 20" .308 with a good scope on a good barrel and with good ammo will tear up a 10-ring at 600 yards.

    Once you make adjustments for the day's conditions, subsequent shots will easily land in the 10 ring with boring regularity.

    Of course, its that first shot that really is the measure of your marksmanship skills.
     
  4. Jack A. Sol

    Jack A. Sol member

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    no. your velocity only effects terminal ballistics and flight pattern. 200-300 fps wont make a huge deal in IF it gets there just where it will hit when it does.
     
  5. MudPuppy

    MudPuppy Member

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    I don't get it.
     
  6. Titan6

    Titan6 member

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    You will lose a bit but I do not understand the question.

    What is ''too much''? What are you trying to do with it? You can adjust your scope and still hit the target even with a 12'' barrel.
     
  7. GunTech

    GunTech Member

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    I use my 20 inch Remington for thousand yard shoots. 600 is not a problem.

    It's all bullet selection and velocity. You can hardly go wrong with 155 gn Lapua Scenars, which have a BC of 0.505. If you want to shoot anything over 168gn, I suggest a 1:10 twist. If you plan on lighter bullets,. 1:12 will work fine.
     
  8. jlbraun

    jlbraun Member

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    1000 meters = 1200 yards. Basically, what he's saying is that the Brits shoot for 1000 meters because it's a nice round number, just like we shoot for 1000 yards because it's a nice round number.
     
  9. browningguy

    browningguy Member

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    What powder are you using, and what kind of MV? I'm going to be ordering a barrel for F-TR class shooting and most of the guys are telling me to go with 28" as optimum, 26" minimum to make sure it stays supersonic at 1K. I've been looking at the Scenar bullets and like the high BC in a 155 gr. bullet for the additional velocity.

    Anyway, back to the question, at 600 yards any of the factory loads would stay supersonic even in a 20" barrel.
     
  10. ArmedBear

    ArmedBear Member

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    600 yards on paper, or 600 yards on deer?
     
  11. jlbraun

    jlbraun Member

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    I heard that I'll only lose about 80fps in a 20" barrel over a 24", and need to go with a 1:10 twist to stabilize 155gr bullets.
     
  12. Davo

    Davo Member

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    Heres a review of an 18 inch tactical .308...
    http://www.borelliconsulting.com/evals/guns/spu308.htm

    You will do fine with a 20@600, but would be pushing hard to get to 1k, which is what I consider long range with the .308
    When I upgrade my Savage .308, I will likley put a 28 or 30 incher on it.
    And remember that bullet selection is more important than barrel length.
     
  13. USSR

    USSR Member

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    80fps can be the difference between a bullet going trans-sonic or not with a marginal 1k cartridge such as the .308 Win. If you're purpose is to shoot F Class, you need all the velocity you can get, and anything shorter than a 24" barrel is simply handicapping yourself further.

    Don
     
  14. Jim Watson

    Jim Watson Member

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    Ectually not, old chap. 1000 metres is 1093 yards or thereabouts. The Brits really do shoot .308s at 1200 English Yards. And some odd distances as local range space requires. There was a match with the long target at 1114 yards at Blair Atholl in Scotland early this year. Closer shots at even 900 and 1000 yards.


    Yes, you can shoot that short barrel at pretty good ranges, I have seen it done. But I would not buy a 20" barrel for the purpose when longer is available.
     
  15. Swampy

    Swampy Member

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    Plus 1....

    If you KNOW ahead of time that your primary use of a rifle is going to be 600 to 1k yard shooting... then it makes no sense to buy the short barrel. You will want all the velocity you can get, especially at the longer range. Either buy a longer barreled rifle, or buy an action and have it barreled with a longer match grade tube.

    Also, re twist rate.... the light 155 grain bullets will stabilize in a 12 to 14 twist. It's the HEAVIER bullets that need the tighter 11 to 10 twist tubes.

    Just my 2 bits,
    Swampy
     
  16. Fatelvis

    Fatelvis Member

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    An M1A will easily shoot accurately at 600 yds., (20" bbl.). A bolt gun can be loaded with slower powder & hotter, so it definately would be effective at 600.
     
  17. Swampy

    Swampy Member

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    Standard GI barrel length on the M14 (M1-A) is 22"....

    Best,
    Swampy

    Garands forever
     
  18. Fatelvis

    Fatelvis Member

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    Thanks Swamp! :eek:
     
  19. The Annoyed Man

    The Annoyed Man Member

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    I've fired my brother's Remington 700 with a 20" barrel at 750 yards, and it proved to be quite accurate once I got it dialed in at that distance. I honestly don't remember the group size though. It was quite a while ago. I currently own a Remington 700 with a 26" barrel and it shoots accurately, although I have not had the chance yet to shoot it beyond 100 yards, nor have I had a chance to compare it head to head against my brother's rifle, so I can't really say what would happen at longer ranges. I have fired both rifles on different occasions at 100 yards, and they are both tack-drivers.
     
  20. Swampy

    Swampy Member

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    Get out beyond 600 yards... let the wind kick up a little, and (All other things being equal... i.e. bullet BC..) the rifle with the edge in initial muzzle velocity will show it's legs.....

    Just my 2 bits,
    Swampy

    Garands forever
     
  21. USSR

    USSR Member

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    Swampy,

    Ya got wind in Missouri too?;)

    Don
     
  22. The Annoyed Man

    The Annoyed Man Member

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    I've no reason to doubt you, and I've heard (although I haven't been there yet myself) from guys I know locally who have used the closest 1,000 yard range to here - Tac Pro, about 90 miles from Grapevine - that it gets quite windy out there too.

    ...and this is TEXAS wind. Not that wimpy stuff y'all have elsewhere! :evil:
     
  23. GunTech

    GunTech Member

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    I'm using 45.5gn AA 2520 for 2675 fps. WW brass and CCI BR-2 primers. Supersonic to 1200 yards. I got another 200 fps from my original 27.5 inch barrel before I chopped it. That would keep me supersonic out to 1400.
     
  24. Jim Watson

    Jim Watson Member

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    I am loading the .308 155 Scenar with 46 grains Varget for 2900 fps from my 28" barrel. I got a 28" because that was the longest Pac-Nor sells without extra charge for extra length.

    My factory barrel was as accurate with 2520 as Varget and it metered like a dream. Unfortunately my factory barrel was not the sort of Savage factory barrel you read a lot of brags about on the Internet and gunzines, so I have replaced it. The Pac-Nor is markedly more accurate with extruded powder than Ball Process.
     
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