Twist rate for a 30 cal xp-100

Discussion in 'Specialty Handgun Hunting' started by Buttermilk, Feb 19, 2019.


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  1. Buttermilk

    Buttermilk Well-Known Member

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    I'm soon planning to embark on my next XP-100 build. Currently planning to do a 30 cal cartridge that hopefully will push a 210-212-215 class bullet to at least 2750, maybe even 2800+ FPS (be nice to achieve 2850fps, just not sure I can get there with a barrel length of ~18"). I have not yet decided which case/cartridge. I will likely do a 30 Nosler, 30-28 Nosler or a similar cartridge. Maybe even a true wildcat, if I decide I need more case capacity.

    One thing I'm kinda hung up on is twist rate. I originally planned to do a 1:10" twist, but now am considering doing a 1:9" twist.

    The Berger twist calculator shows that a 10" twist would be adequate, but I'm still considering doing a 1:9" twist. Partly due to the lower expected velocity that my XP-100 will generate compared to a rifle length barrel with same/similar cartridge.

    I don't really have any plans to shoot the heavier 230+ bullets since I'm primarily going to use this gun for hunting. Maybe the occasional long range target, but still likely with 210-212-215 class bullets.

    Anyone here ever did something similar?
     
  2. Buttermilk

    Buttermilk Well-Known Member

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    I went with a 9" twist. :)
     
  3. J E Custom

    J E Custom Well-Known Member

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    NoT sure that the case capacity of the 30 and 26 Nosler is well suited for the short barrel of a pistol. I'm not trying to talk you out of these cartridges, but don't expect these velocities.

    In pistol length barrels, a cartridge with a short powder column seems to work best and something like the WSMs or the RCMs work well with magnum charges.

    just my opinion

    J E CUSTOM
     
    Last edited: Feb 21, 2019
  4. Buttermilk

    Buttermilk Well-Known Member

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    I’ve done a few cartridges in short bbls. The achievable velocity is surprising.

    Won’t get rifle bbl velocity, obviously, but they do quite well.

    I know of two 300 RUMS built on XP-100’s that obtained 2800-2825 fps with 230’s, and at least one 28 Nosler has done 2800 fps with 195’s in a short bbl.

    My own 7 SAUM, 30-338WM and several others I’ve had have done quite well too.

    The two cases listed above, the WSM & RCM, won’t hit my velocity goal.
     
    Last edited: Feb 21, 2019
  5. yorke-1

    yorke-1 Well-Known Member

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    I don't think you'll have a problem hitting your velocity goals with either the 30 or 30/28 Nosler in an 18" barrel. You can have the chamber cut to run whatever OAL you want so you'll gain a good amount of usable capacity in the single shot.

    The easy way to guarantee you'll hit 2800 fps would be to go with the 300 RUM, but that can be too much of a good thing sometimes! LOL
     
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  6. Buttermilk

    Buttermilk Well-Known Member

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    Today, I made a decision on cartridge. I will be specking a reamer soon.
     
  7. BClrh

    BClrh Well-Known Member

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    This is an older thread but what did you go with and if the project is completed how did it work out?
    I have been looking at a short barrel 300NM to push 215 bergers. I Like H1000 but I don't know if you would get a complete burn in an 18" barrel and I am a little concerned about the muzzle blast.

    What powders were the guys with the rum's mentioned above running and how's the muzzle blast?
     
  8. Buttermilk

    Buttermilk Well-Known Member

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    I have chosen the 30 Nosler. Project is not yet completed.

    I shoot H1000 in a 17.5” 7mm RSAUM. I get my highest velocities with that powder in that cartridge and short barrel.

    I would not worry about complete burn in short barrels. All the powder burns in the first 3 inches. If you ever scrutinize a pressure trace, you’ll see this is true. Longer barrels simply use the volume of gas created more efficiently than shorter barrels.

    I have done a lot of short barreled setups with fairly large capacity cases. All have performed quite well.

    I am not certain in what the guys were using in the 300 RUM short barrels.
     
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  9. BClrh

    BClrh Well-Known Member

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    My plan is to run the 18" on a bullpup. With your experience with short barrels do you think the muzzle blast would be to harsh? I have never shot a barrel that short but in normal barrels it never seems bad with hearing protection when your the shooter. If your to the side its a different story.
     
  10. Buttermilk

    Buttermilk Well-Known Member

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    Your asking a specialty pistol shooter if the blast will be too much. For me, the answer is no.

    Now, these shorter barrels do indeed have more blast than a longer barrel. They have more noise as well.

    But so does a muzzle brake on a long rifle barrel.

    I wear hearing protection at the range and even while hunting. So, the slight increase in blast and noise isn’t an issue for me.

    If you want a short barrel, then by all means, do a short barrel. After all, your doing this to suit your needs and wants, not anyone else.
     
  11. Flintlock

    Flintlock Well-Known Member

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    Did you look at the 300 SAUM? I have one in the HS Precision , 15" with 2" break and all of my load data show about 2950 to 3000 with 150grn Accubonds and H4831SC powder. I know one thing, the deer here in OK were sure upset that I got it. With the Burris 3x12 BP and using a BogPod Deathgrip I have taken several doe out to 300 yards and closing with it and they dropped at the shot and there was a lot of damage internally when field dressing. Have to keep it off the shoulders. One doe was shot walking and hit on the shoulder and out the shoulder. Both were not even good for grinding.
    Have you got your 30 Nosler up and running?

    Mike