How to get consistent velocity with straight wall cartriges

Discussion in 'Reloading Forum (All Calibers)' started by Carter Shinavier, Jan 23, 2020.

  1. Carter Shinavier

    Carter Shinavier

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    I recently picked up a 45 Raptor for hunting in Michigan, and would really like to stretch the legs on this bolt gun. Obviously, with a 250 grain low BC bullet, getting consistent velocity is going to be really key to long range accuracy. I have loaded a couple of other straight walled cartridges and have gotten them to group well at 100 yards, but have never really found the sweet spot for consistent velocity. For what it is worth, i don't have an issue with getting low ESs in my bottle neck cartridges, so I think that I'm missing something as it relates to straight-wall cartridges. Please advise if you know what is different, or what I might be missing. Thanks.
     
  2. Terry

    Terry Gold $$ Contributor

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    What is your current ES?

    Jumping or Jaming?
     
  3. Richard Coody

    Richard Coody Silver $$ Contributor

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    Well i really don't think that cartridge was designed for benchrest accuracy. It was designed for the AR platform. The bullets themselves have very poor BC.

    If i were trying.to get the best out of it after accurate powder charges, load development, seating depth testing (don't believe i would even try a jam) , primer testing.

    I believe i would work on neck tension. This cartridge would probably benefit from testing crimps. I would start with a light crimp and work from there. I think it might be the best way to get consistent neck tension which might be the path to consistent velocity.
     
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  4. Carter Shinavier

    Carter Shinavier

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    The ESs I was seeing with loads so far are 80-100 FPS. I am jumping .030" currently. I do not want to jamb being a hunting cartridge. I'm not looking for benchrest accuracy, but the guy I purchased the barrelled action from produced images of sub 1/2" 100 yard groups. If I can get he ESs down, I should be able to predict results at 300. If I can remain sub 1 moa at 300 yards, with a small margin of error, I would be more than happy. Crimp adjustments make sense to me, though I do not know how to precisely measure crimps. Maybe you could enlighten me on that.
     
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  5. damoncali

    damoncali Bullet Maker Site $$ Sponsor

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    I would play with crimps and primers.
     
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  6. mikeinct

    mikeinct Silver $$ Contributor

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    For best crimp. Maintain similar trim length & then sort your best by eye. mike in ct
     
  7. JEFFPPC

    JEFFPPC Silver $$ Contributor

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    I recently purchased a 450 Bushmaster in a Mossberg Patriot as I hunt southern Michigan also. It shots an inch out of the box with factory ammo, which is how I am going to handle ammo for 1 or 2 shots a year.
     
  8. Carter Shinavier

    Carter Shinavier

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    I can appreciate using factory ammo for very occasional shots, but my hobby is shooting (all of the time) that I take to the field for hunting (2 to 3 times a year). In this case, I am looking to stretch the limits of this cartridge. It's kinda like the pumpkin chucking contest....I want to because I can, and because the bullet still has sufficient energy at 300+ yards to effectively take a deer. The starting velocity of this bullet out of this rifle is over 2700 FPS. Just need to know some secrets to getting the ESs down.
     
  9. XTR

    XTR

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    From the look of the cartridge it looks like you’re going to be going down the same road that the guys who try to load smokeless powder and a 45-70 go down. It’s hard the case is probably over capacity for the powders that work, though it is .3 inches shorter than a 45-70.

    First you’re gonna have to play with a number of powders and find one that gives you a hundred percent fill or close to it to achieve the velocity that you’re seeking. Something the 47-70 guys found out is powder that has room to roll about in the case doesn’t always light the same way.

    Without looking at reloading data I’m going to guess Rx7, 5744, 3031, or 4198 may work. And the next step is going to be to change one thing at a time and find out what works the best.

    something to consider though, 100fps is only going to make about two to two a half inches difference in POI at 300 yds from a 100 yd zero. A 250 running 2700 is going to have some recoil. The shooter is going to have to learn how to handle the rifle.
     
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  10. sawcarver

    sawcarver Gold $$ Contributor

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    Also living in Michigan Ive done a fair amount with straightwalls and distance. .444, 45-70, 375 Win .357max, now playing with .350 Legend

    Heres what I do
    No crimp
    Universal length on cases
    Try to get 100% fill or sightly compressed loads.
    Primers make a bigger difference so try a few types.

    Currently we use 357 Maxs with 150gr cutting edge raptors and kill deer 400+ yards with them
     
  11. CharlieNC

    CharlieNC

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    When I got my 45-70 a couple of years ago I didn't know any better and ran a ladder test, got the widest node I have ever seen. Maybe you can get lucky too, and minimize velocity worries.
     
  12. rsmithsr50

    rsmithsr50

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    uniform case length,
    if no crimp, work on neck tension.
    before skipping crimp ensure bullets are not moving in the case
    while shooting/chambering
     
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  13. bozo699

    bozo699 Gold $$ Contributor

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    Spot on! That can become very dangerous very quickly!
    Wayne.
     
  14. XTR

    XTR

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    Sub MOA at 300 might be doable, but as I noted above, there is a hella lot more to getting groups from a big thumper than there is from a bottleneck mouse fart. The recoil is big, but more of an issue for me, the torque is huge, combine that with a semi auto platform and you might be a little optimistic.

    I don’t doubt that you can get it to under 2 MOA at 300 with some work, which will work for hunting. I made the mistake of trying to shoot my 45-70s one yr in the middle of my F-TR “season”, completely farbed my gun handling at the next match. It’s different. In addition to the loading challenges you have to hold hard, and that’s not usually how you shoot small groups.
     

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