300 WM with 20" need advise...

Discussion in 'Reloading' started by Armored Transport, Jun 16, 2012.

  1. Armored Transport

    Armored Transport Well-Known Member

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    I have everything for my build at fine Smith ( and best friend ) ready to go together. I recently heard a descusion on barrels and was thinking of giving a 20" a try in this caliber. Being new to reloading I was wondering what powder would be best with a shorter barrel in the 300WM ? I was watching a video from Accuracy First / Magpul and the instructor ( Todd H. ) is a big fan of heavier / shorter barrels ( 20" ) and a faster twist rate for long range shooting. I know there is some loss of FPS and that is mentioned in the vid. as well. I would like to have some input from the shooters at large on this. Thank's for your time.............Rickgun):D
     
    Last edited: Jun 16, 2012
  2. highridge1

    highridge1 Well-Known Member

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    20 inch barrel just doesn't make sense to me in a 300 win mag. Would be a much better fit for a .308. With a 20 inch barrel in 300 win mag you are simply getting 30-06 performance.
     

  3. D.ID

    D.ID Well-Known Member

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    +1 30-06 performance with more expense, recoil and muzzle blast. less magazine capacity. All the negatives of a magnum without any of the benefits, I wouldn't do it but at the same time I am sure someone has, so you would not be the first to do something that just didn't make sense to me, she is your rifle I hope you enjoy it either way....good luck
     
  4. D.ID

    D.ID Well-Known Member

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    P.S. I have heard of some benchrest guys and pistol shooters putting magnums in short barrels but even if it reduces whip in the barrel it seams more novelty than practical application...................Disclaimer: All this is coming from a guy with a 24" 338 edge (which I love) so judge my opinion accordingly.
     
  5. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Not quite on the '06 performance in a 20" barrel. My father has one of the savage stryker pistols with a 14" barrel in 300 wsm and it will turn in average '06 sporter velocities.
    If you want to do this you will loose some speed, and you will land midway between the '06 and 300 win in actual velocity. I've been working with contenders and strykers for years, and 400 fps loss to go the pistol barrel is about it.
    The trick is to find a powder whose energy is expended by the time it gets to 20". Use the fastest powders that produce full velocity in your cartridge. rl17, 4350(both h and imr), 760, etc. for mid weight bullets in the 300win. If you step up to 180, I'd go to 4831 class, but no slower than rl22.
    If I were a betting man, I'd say you can still net 3200 fps with a 150 and 2900 fps with a 180.

    P.S., the short barrel absolutely helps accuracy. My stryker pistol (22-250) will pitch 5 shots into an inch at 100 yards with one sandbag under the heel on the pistol(4x leopold on top), and I've killed prarie dogs at 1/4 mile with one of my father's strykers.
     
  6. D.ID

    D.ID Well-Known Member

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    I know conventional wisdom says the shorter barrel will have less whip and a short action is more rigid but I have a long barreled, long action that can do .25" @100 so you have to ask how much it really matters.
     
  7. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    It's more a fact that anything you put through the short barrel shoots better. I've got 26" barreled la sporters and they shoot well. I've seen pistols with 14" barrels turn in 5 shot .25"-.5" 100 yd groups with a 4x scope, and I've done it a bunch of times myself. If you don't have to worry nearly as much about harmonics, you can get the gun going quickly and get used to your load, instead of playing the load hunt game.
    By the way, the 300wsm pistol I refered to has a 14" barrel including the muzzle brake.
    It's what the OP wants, and it might just be a tack-driver.
     
  8. D.ID

    D.ID Well-Known Member

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    I agree if it's what the op wants, heck ya why not. I realize the "fact" but my point was the gain in accuracy is insignificant. .5" @ 100 is nothing special, it is just a well built machine doing it's job, regardless of barrel length, action length or any number of other factors. By all means build it.
     
  9. Mikecr

    Mikecr Well-Known Member

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    Well, it's also a 'fact' that higher muzzle pressures (all else equal) hurts accuracy.
    And this is why longer barrels work better, and more accurately in large capacity cases, than barrels that are too short.

    Whenever you go to any extreme, with anything, you pay a price.
    You wouldn't want to go ridiculous long for a little more velocity, adding whip.
    And you don't want to go ridiculously short for accuracy, adding fireball.
    Both hurt accuracy.
    What point blank BR shooters do, is far far away from LR hunting/shooting with a rifle in 300wm.
    PB BR shooters can take advantage of ~22" barrels because they're shooting the tiny 6ppc with a very fast powder, resulting in low muzzle pressures despite. They're also using better releasing FB bullets.

    I would go 28-30" for a 300wm. With this, you can burn a hi% of the powder INSIDE the barrel instead of hitting the releasing bullet base with a giant blast of spiking pressure OUTSIDE the barrel.
    You can use a larger diameter & fluted barrel for stiffness/weight, get very clean bullet release, and better accuracy than you're gonna end up with from 20".
     
  10. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Yes a longer barrel will give you lower muzzle pressure, to a point. If you use powders that are on the fast side for your given combination, you can get along with a lot shorter barrel than if you're using a compressed charge.
    I pulled out some pressure graphs from my old 7mmstw, and though the pressure was still dropping as the bullet exited, the pressure was below 20,000psi at 1.5 milliseconds, while it has only dropped to 12,000 psi at 2.5 milliseconds. Neither pressure is doing much to move the bullet. The load was 81 rl25, 140 sierra fb, 215, rem. brass. The pressure peaked at 60,000 psi at .6-.7 milliseconds.
    I highly doubt he'll notice any difficulty shaving down to 20" from the normal 24" of a lot of the factory 300win's out there. 100-150 fps would be a lot with equal or better accuracy if he watches his powders. I wouldn't burn ball 50bmg powder or retumbo in this one, though. That would CREATE problems on its own. Stick to the idea that the pressure needs to be off by exit, and use mid-speed powders.
     
  11. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Another thing that hasn't been brought up. Why not go with a 24"-26" barrel and a single shot action if shorter is a premium. That way you can use any powder you want and stay stiff enough to be accurate in a sporter taper. My 338 is a #1, and while it is rather critical as to hold and bagging for accuracy, I'll put it up against most any rifle out there short of a ppc for accuracy.
     
  12. backwoods83

    backwoods83 Well-Known Member

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    Even with Imr4350 and 165s in a 20" tube its a giant fireball, build it if you wish, but I call it pi$$ing in the wind!
     
  13. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    I don't get a fireball with my 22-250 in a 14" barrel. My father doesn't get a fireball with his 300 wsm with a 14" barrel.
    You have got to get a shorter barrel to see it's capabilities before you summarily strike them down. If our 14" barrels are just fine, why will his 20" barrel be a problem??
    I've shot I've shot 300 win's with 22", 24", and 26" barrels, and you loose a few fps, but it's more the barrel (whether it's fast or slow) than the barrel length.
     
  14. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Kinda funny-- 4350 and 165's shoots pretty well out of my father's 300wsm. He went to that a few years ago, before that he was using a 150 and varget, if I remember.