300 wsm 125 NT 4000 FPS Is it possible????

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by reed mosser, Nov 2, 2006.

  1. reed mosser

    reed mosser Well-Known Member

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    I have seen know two times about 300 wsm's 30 inch barrel 15 twist and 125 nosler BT at 4000 fps. I just read the article on 6 br.com and seen it on bartlein barrels web site. I have a 10 twist 30 inch tube 30-338 laupa mag improved. And at max load can only get 3750 with 150's. And I know with 7 wsm's the fastest barrel i have ever seen will get 3675 fps with 120 nosler bt's. I hope this is the real thing but i really can't believe that twist has that much to do with velcioty. Thanks again Reed
     
  2. sewwhat89

    sewwhat89 Well-Known Member

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    I was thinking the same thing. I plan on trying some 125 NBTs in my RSAUM this winter, but I was only shooting for about 3500 fps. I can't see how it works, but I think keithchandler or one of the other .25-06 shooters on this site has experience with awesome velocities and accuracy using a 1:12 or 1:13 .257 barrel with 75 gr AMAX. It parallels the article on 6mmBR.
     

  3. 1doug

    1doug Well-Known Member

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    reed in reading the article too, i understood that the gun was purposly built for the 118-125 class bullets. It should not stabilize a 150 or heavier bullet.

    the slower twist is why he can acheive that velocity where as you and me with a 10 twist can not.

    d-a
     
  4. Jimm

    Jimm Writers Guild

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    Reed,

    I am getting 3650 fps out a 28" 11 twist Broughton caliber 300 WM using a 110 gr.vmax . Very accurate as well (1" @ 300 ).

    Pressure is below max so it doesnt seem much of a stretch to purpose build a 300WSM and attain those velocities . That it is accurate is what is harder to swallow /ubbthreads/images/graemlins/shocked.gif /ubbthreads/images/graemlins/laugh.gif

    Jim B.
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Reed,

    In my opinion, I would say he is running things pretty hard. One example, look at the Lazzeroni 7.82 Warbird loaded with the 130 gr X bullet. In a 28" pipe this round tops out at 4050 fps and they are using slow twist barrels in this round as well. I believe they use 1-13 or 1-14 twists in their rifles.

    Now this is a round with a 105 to 110 gr capacity depending on what powders you use and it will just get over the 4000 fps level with a 130 gr pill.

    Obviously the 300 WSM is more efficent but there is only one way to generate FPS and that is to apply pressure to the base of the bullet. The longer the pressure is applied to the bullet, the more velocity you get. Thats why longer barrels generate more velocity.

    Also, the higher the pressure you can maintain farther down the barrel, the higher the velocity will be at the muzzle. THat is why really slow burning powders in smaller bores and long barrels will produce higher velocities then faster burning powders in the same barrel length with the same bullet, simply put, the pressure remains higher for a longer period of time.

    Peak pressure may be the same or even higher for the faster powder but velocity is a function of pressure and time as we all know.

    For that reason, I feel that this is really pushing things in the 300 WSM. For one thing the case is not large enough to hold enough slow burning powder for that to be the reason for the high velocity.

    I suspect he is running pressures very high in a very tight fitted chamber to control case stretching as much as possible but I would still say he is pushing things very hard to get this velocity level in the 300 WSM.

    Rifling twist does not mean that much as far as velocity potential. That comes right from Dan Liljas mouth. In two barrels with the same bore diameter, Dan says that dramatic velocity change from a fast twist to a slow twist is really a wives tale.

    He said what does make differences is bore diameter, land wideth and bore finish more then anything. He said these effect velocity potential much more then twist rate ever will.

    Also, I personally feel throat design and throat angle have a great amount to do with velocity potential. One example of this is a couple 338 Kahns I have built for my family. One mine, the first one I ever built and one my brothers.

    On mine, my chamber has the original design 3 degree throat angle, very steep. I top out at 3050 fps with the 300 gr SMK. This seemed pretty low to me so I ordered in a throating reamer with a 1.5 degree throat angle and used that on my bothers rifle.

    Using the same load I use in my rifle he gets 2975 fps and in a 2" longer barrel. The half as steep throat angle dropped chamber pressure dramatically. The interesting thing is that it allowed him to use an extra 10 grains of powder before topping out with the same pressure signs as my rifle.

    At his top end load he can get 3175 fps compared to my 3050 fps. Just the change in throat angles frees him up for an extra 125 fps. Now the extra two inches of barrel will account for about 30 fps of this but we are still looking at a 100 fps gain just in throat angle.

    Free bore does the same thing.

    Without knowing how his chamber is set up I should not say anything because with a chamber designed specifically for speed only, he would generate much more velocity then a standard chamber. That said, if he is reporting this velocity potential and he does have a special chamber design and does not report that as well, he is not being very responsible with his reports as it could be dangerous for someone with a standard 300 WSM who things they can get these same velocity levels.

    I have seen a couple 30" barreled 300 RUMs reach this level with the 125 gr Ballistic Tip. I think Bill Bailey was doing this when he started into LR shooting but he has since learned a better way!!! /ubbthreads/images/graemlins/grin.gif

    This is top end in a 300 RUM, I just can not see the WSM getting this level of performance using safe pressures, that being nothing over 65,000 psi.

    Just my opinion,

    Kirby Allen(50)
     
  6. Centre Punch

    Centre Punch Well-Known Member

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    I'm glad someone brought this one up, i thought the same as you Reed, i even checked a load of handloading data and nothing came close.

    Ian.
     
  7. remingtonman_25_06

    remingtonman_25_06 Well-Known Member

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    I got 3950fps with RL-22 and the max load according to nosler out of a 26" 300 RUM. Didn't shoot anything with them though.
     
  8. reed mosser

    reed mosser Well-Known Member

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    I agree with everyone. It seemed to be to good. I too have learned that you have to pay for speed in either amount of powder or pressure. I think he has to be running a extremely hot load. Thanks again