338 Lapua Mag barrel

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by vballcop1, Dec 2, 2008.

  1. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    I'm currently building a 338 Lapua long range rifle and am looking for a 20 inch barrel (+ muzzle brake). I would appreciate any feedback regarding manufacturer and twist rate combinations that worked or didn't.
    gun)
     
  2. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    20" barrel? Why so short?
     

  3. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    I recently got my paws on a Sako factory long range gun. It is a Military contract set-up and sported a 20 inch barrel with a 1 in 9 twist that produced some great results. I've always liked the short barrels for hunting and was in the process of building a lapua. I hadn't even considered the shorter barrel until seeing it up close. Now I'm both curious and interested! The balance of the shorter barrel is a big plus for my use and the slight velocity loss doesn't deter me alone.
     
  4. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    While their is no dought as to the accuracy potential of a short barreled rifle, but a 20" barrel will not take advantage of the case capacity of the Lapua round. The 338 Lapua (338 Edge, etc) are at their best when shooting very higb BC bullets such as the 300 grain SMK with a BC of .768. I personaly would not want a 338 lapua with a barrel shorter than 26" inorder to get as close to 2800 FPS as I could with the 300 grain long range bullets. If I were going with a 20" 338 then I would not use a case with more powder capacity than a 338 Win. That's my opion my 338 Laupa hax a 31 1/2" barrel including the brake.
     
  5. Longshot38

    Longshot38 Well-Known Member

    Messages:
    151
    Joined:
    May 3, 2008
    If you want to rifle with a 20 inch barrel for hunting get a 308 winchester. The 338 lapua/edge/AM are all rounds with large case capacities and do best with long barrels, slow burning powders, and heavy bullets. A 20 inch barrel on a 338 lapua is more of a flame thrower.
     
  6. hammertyme

    hammertyme Well-Known Member

    Messages:
    357
    Joined:
    Oct 2, 2008
    I have a 17" 338 X 378 Weatherby Imp plus brake in a handgun configuration.
    2900FPS+ with a Lehigh bullet. The bullet type and the weight will determine what twist.

    Like previously asked why such a short barrel for a rifle?

    Neal
     
  7. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    Make no mistake...I have a platform for a 338 well on it's way. The barrel is the last piece it needs. I was eyeballing barrels in the 26 inch class, but the 20 inch one I saw beat my standards minus 6 inches. I was wondering if anyone out there has any experience with a shorter barrelled a 338? If so it would save me a lot of time and $$$ learning from thier experience.
     
  8. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    Define small loss in velocity.
     
  9. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    I'm not sure...how much would be lost?
     
  10. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    ;) According to my calculations Shortening the barrel by 4 inches should reduce velocity by 100-150 fps. Assuming the 2800 fps and a BC of .768(Sierra)...that only reduces my POI 23.5 inches or 2.3 MOA at 1000 yds(Hornady). Am I missing something?
     
    Last edited: Dec 2, 2008
  11. jwp475

    jwp475 Well-Known Member

    Messages:
    2,595
    Joined:
    Feb 4, 2005
    !00 fps will lower bullet impact a lot more thn 4.1" at 1K.
     
  12. Longshot38

    Longshot38 Well-Known Member

    Messages:
    151
    Joined:
    May 3, 2008
    You are probably looking at more of a 200-300 fps velocity loss. Remember that slow burning powder thing I mentioned earlier. With that short of a barrel I doubt you will reach optimum chamber pressure before the bullet exits the barrel. Now if you are lucky and do a lot of load development you could probably manage only about 100 fps loss if you used faster burning powder.

    It is like this. In calibers with smaller case capacities a short barrel is a good thing for several reasons. But with large rounds such as these there is a lot of SLOW burning powder behind that bullet that needs to burned up prior to the bullet leaving the barrel. You simply can't burn up that much powder in a 20 inch barrel and you will end up with a combination flame thrower/rifle.

    Am I saying that it is impossible to have a good accurate 338 with a short barrel, no, just saying that these rifles really NEED a 26+ inch barrel to get the most out of them. So if you have your heart set on that 338LM with a 20 inch barrel go ahead and do it. But the answers you'll get here will all say the same thing. For this round long barrels are good.
     
  13. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    Sorry, :( I have edited the original post. The correct drop is now listed. That's what I get for working while I'm typing. HA! But I have more now that I've had a minute to do the math. Apparently everyone has an opinion, but I'm the only one willing to put out the facts.
    The exact muzzle velocity change I can't determine with my data, but it should be just around 100 fps. Now for the details..

    :rolleyes:That translates into 23.5 inches difference at 1000 yds. You might say this is significant, but lets compare... The overall drop is now 293.8 inches!! So how much difference is that 23.5 inches? Well the beloved 308 winchester at 1000 yds even at the apparent loved barrel length of 26 inches drops a 200 gr bullet 540 inches....I heard the 338 win mag mentioned...it drops the same 300 gr slug 422 inches at 1000 yds. The lapua is still 128 inches better than a 26 inch barrelled 338 win mag even at 20 inches. Seriously I'm not busting anyone's balls. I can argue ballistics all day, but I want to know if anyone has used a short barrel and how it worked. I'm not a first time gun owner and I think this would make one heck of a rifle.
     
  14. vballcop1

    vballcop1 Member

    Messages:
    9
    Joined:
    Dec 2, 2008
    I actually found a link that gives a similar powder chart and barrel length test. The gun used was not a 338, but it did use the same powder as in the 338. The barrel was cut in 2 inch increments and the results were around 115 fps. I really thought it would be more myself, but that's why I'm looking for someone who has already done it. I'm not sure burning my eybrows off is my desired result. LOL. I really would love to find out what the exact numbers are. I'm trying to wiggle them out of Beretta, but since the gun is not civilian production they are not very open to sharing:(! I do appreciate your insight. Like I said, I know what it sounds like! I just figured there's someone who has already tried it or has a direct answer about the actual minimum barrel length required to reach the max pressure. Feel free to keep posting..I have to go my 1 year old is ripping my printer apart! Thanks