Velocity Question?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ovastafford, Jun 1, 2011.

  1. ovastafford

    ovastafford Well-Known Member

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    What kind of velocity can I expect out of a 26" barrel with out of a 6.5-284 with 140gr berger vlds, retumbo powder, lapua cases?

    Thanks
     
    Last edited: Jun 1, 2011
  2. Team Roper

    Team Roper Well-Known Member

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    2950 to 3000
     

  3. rscott5028

    rscott5028 Well-Known Member

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    I agree with Team Roper.

    I've only shot one ladder with my new 6.5x284. But, I was getting 2898-2907 from my 24" barrel using 51.3gr H4831sc and 142gr SMKs.

    That's listed as a max load. But, I didn't see any signs of pressure.

    2" more should be worth another 50-100 fps.

    -- richard
     
  4. Coyboy

    Coyboy Well-Known Member

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    I was shooting Richards listed load in my f-class gun, a 30" barrel was giving me 3025 fps.

    started to show some pressure with barrel heat during long stings of fire, so today I loaded down 200 cases to 50.6, and I culled out about 12 pcs of twice fired brass that had loose pockets.

    Retumbo might be a tad slow for it.
     
  5. ovastafford

    ovastafford Well-Known Member

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    Yup around 3,000 was where I started to see pressure signs. What about H4350 and 4831?

    Thanks
     
  6. trebark

    trebark Well-Known Member

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    H4350 is a great powder for 6.5mm cartridges. I send the 142SMK at 2950fps with 43.5grains of H4350 in my 28" barrel 260Rem. http://www.longrangehunting.com/forums/f53/my-260-mcr-59628/

    Given the 6.5x284 is a larger case than the 260, I would think you could easily at 3000fps with the 140grain class bullets.
     
  7. rscott5028

    rscott5028 Well-Known Member

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    The same 51.3gr of h4831sc in my 30" (1:8") Savage 12F only gained me about 50 fps vs my 24" (1:8.25") Kreiger barrel with a match chamber. And, it was beginning to show some signs of pressure in the Savage.

    I would've expected a bigger gain with a 6" longer barrel whereas Coyboy reports 125fps gain with his 30" barrel.

    Maybe this new rifle is exceptional? Or, perhaps my chrony is off? I wonder now how much difference there is in the COAL/case capacity?

    I guess it just shows that every rifle is different.

    --richard
     
  8. Mikecr

    Mikecr Well-Known Member

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    Based on what I can tell with QL, you can expect 2950fps with Retumbo -26" barrel
    You could get 3050fps using Ramshot Mag.
    And then 3150fps from a 30" barrel and Ramshot.

    Problem here is your barrel is too short for such a large capacity case.
    You lose the potential of this cartridge, and you create ugly bullet release due to excess muzzle pressure.
    I could surpass every single aspect of your 6.5x284/26" barrel with a 260AI/6.5wssm/28" barrel, because the capacities of my approach better match.

    But a properly set up 6.5x284 could easily leave me in the dust.
     
  9. rscott5028

    rscott5028 Well-Known Member

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    Every cartridge/rifle has its sweet spot. Some are just sweeter than others.

    They all look good on paper within some set of parameters if you manipulate the figures.

    To your point, it does behoove you to start with a plan that looks good on paper before you build a rifle.

    I chopped mine to 24" which is against common practice just for the heck of it. I was building my first rifle from the ground up and didn't want to potentially booger an expensive barrel. So, I started with a used Kreiger off of a palma rifle with about 900rds and set it back 1 inch, then cut the muzzle and crowned it. I am amazed at the accuracy as well as the velocity. Then again, I've only fired one ladder test with several 3 shot groups under 1/2" at 100yds. I have a few more things I want to do including muzzle brake and bedding.

    My son will mostly be shooting it out to about 500yds and I think it'll smoke a whitetail or coyote at that distance.

    As to the OP, 26" may not maximize the cartridge for competition. But, it's plenty capable of being a great shooter.

    -- richard
     
  10. ovastafford

    ovastafford Well-Known Member

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    Whats the best powder match for a 26" barrel?

    Thanks
     
  11. Mikecr

    Mikecr Well-Known Member

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    I'm not talking folklore.
    I'm suggesting that a better design brings you to fast enough powders to burn up -before bullet exit, yet allowing cartridge potential to actually be reached(without early pressure).

    A 6.5x47 in 26" barrel for example, would provide 26cal performance on a whole better scale to 500yd coyote/deer. It would do this with easily twice the barrel life AND accuracy, over a short-barreled 6.5x284.
    A 260AI would do it further than a 6.5x47 with a 28" barrel.
    A 6.5x284 extends even more in 30"+ barrels, and using the right powders(not H4350).

    As you go up in scale, barrel life drops, and balanced hunting gun bulk increases.
    So if the objective is a shorter/lighter/more accurate gun, then you wouldn't go larger in capacity than providing exactly what you need..

    Well, I guess I'm assuming anyway that OP has a choice..
     
  12. rscott5028

    rscott5028 Well-Known Member

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    Mike,

    Where did you come up with these specifics?

    Thanks!
    Richard
     
  13. Mikecr

    Mikecr Well-Known Member

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    My familiarity wth 26cal cartridges, stems from experience in 6.5wssm, which is currently dead in the middle of them.
    My use of QL and personal software is pretty accurate, as validated at Reloader's Nest, and many forums over the years. And I've looked at every 26cal combination, as well as others.

    ovastafford
    YOU'LL likely find that faster powders provide better accuracy.
    This, because faster powders will burn within even too short of a barrel(instead of 3ft beyond), but will of coarse cause pressure signs way below the cartridge's potential..
    Your muzzle pressures will still be high, so accuracy will still be limited with boattails. And there aren't alot of good flatbase bullets in 26cal..
    I'd follow Richard, or replace the barrel.
     
  14. ovastafford

    ovastafford Well-Known Member

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    Okay thanks for all the help but here is what I got. I have a brand new custom brux 26" barrel on a surgeon action, bedded in a grey bull stock. The first day I started out with retumbo working 55grs up to max, lapua brass cci mag primers, 140gr berger vlds 2 thousands off the lands shooting through a chrono. It was about 60 degrees and cloudy with chrono 15' from muzzle.

    55gr- 2,864, 2,799, 2,805

    56gr- 2,867, 2,900, 2,836, 2,903, 2,875

    56.5gr- 2,921, 2,893, 2,897, 2,898,2,905

    57gr- 2,948, 2,939, 2,900, 2,902, 2,898.

    Nearly all loads were under an inch at 100 yards, I waited a minute or two between each shot. In fact 56gr went into one ragged hole.

    Since I wasnt getting very consistent velocity I switched to H4350 the next day.
    Groups opened up to around 1.5" to under 1" with some.

    46.5gr- 2,808, 2769, 2,770

    47.5gr- 2,844, 2,839, 2,860, 2,878, 2,939

    48.5gr- 2,914, 2,915, 2,911, 2,945, 2,920

    49.0gr- 2,890, 2,898, with pressure signs so I quit.

    I guess Im kinda lost what do you guys think I should do next? Play with seating depth, change primers, I noticed noone uses mag primers. This is the first time I have thrown a chrono in the mix and its added a whole new variable. What do you guys think?