Fat bottom gurls....

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Outlaw81, Jun 16, 2011.

  1. Outlaw81

    Outlaw81 Member

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    Ok, I've been on this 300wsm trip lately. I went ahead and bought another one and I honestly think I'm gonna just stick with this caliber and see what monsters I can build out of it. Yesterday I picked up a Savage 12 Varmint Low Profile in 300 wsm. I handloaded with winchester brass, WLR Primers, 60gr of H4350, and 190smk's. I was expecting roughly 3/4" @ 100 since it's brand new. Nope. I managed a five shot ragged hole at 100 after my 5 shot sight in. I went on out to 250. I managed a 5 shot group that could've been covered with a dime!!!!! This has been a go-to load for me for a few years now in this caliber. Coal is 2.889" and it chronoed 2895 out of a 26" stock tube. ES was about 15 fps. A couple years ago I got tired of people saying the 3short mag couldn't hang with the .300 Win Mag. So I set out to prove to myself it could. I had a long lilja throated for a 3.15" WSM. with this setup you can actually push the 240 smk to about 2750 without pressure signs. My 300 win mag can only get about 2650. The shorter cartridge can burn powder more efficiently than the longer one and with the correct length, can beat the longer one. I built that one off a remington 700 long action, with a custom dbm and 28.5" tube with a 9 twist. So, in reflection; beware of the Fat bottom gurls...(WSM, SAUM, WSSM's) you might just fall in love!! [​IMG]
     
  2. madcharlie61

    madcharlie61 Member

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    Im a fan of fat bottom girls but mine is a little slimer than yours.
    i have a 6.5x284 that is cool and i like but my mate got a 284 at the same time and his is wicked. These little cases really punch outside there size and i think its because of there wider bottom than other med bolt face cartridges. id love to know the reason why short fat cases work better than long thin cases
     
  3. Outlaw81

    Outlaw81 Member

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    I think it all has to do with shoulder angle and length. The ability to fully utilize a slower powder is awesome. That's the whole reason that people bother with the ackley improved versions. You are super correct on the .284 body belonging. I built one two years ago in straight .284 chambered for 180's. Its an awesome weapon. I've never messed much with the 6.5's cause I tend to shoot 155gr and larger pills.
     
  4. LouBoyd

    LouBoyd Well-Known Member

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    You should love the 300 and 338 Norma Magnums. The ultimate "fat bottom" civilian cartridge is the McMillan " Fat Mac". It's a 50 caliber cartridge with 406 grains case capacity but only 2.630" case length.
     
    Last edited: Jun 17, 2011
  5. bigngreen

    bigngreen Well-Known Member

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    I have an addiction to fatties with slow powders, the 270 WSM is my girl :D I must have some of the new Norma Mag stuff but it keeps getting on the back burner :rolleyes:
     
  6. matt_3479

    matt_3479 Well-Known Member

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    That's awesome. I'm a 300. WSM kind of guy. Few years back I wanted something that would take game out to 500-600 easily without going to big, and I was going choose either a 300. Win mag or 300. WSM and everyone rippled up the WSM but anyone who owned on takes so highly of it. I picked one
    Up and love it!!
     
  7. afp1

    afp1 Well-Known Member

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    I love the 300 WSM. My best 1K BR rifle was in 300 WSM and it dominated the competition. I currently have a 7.75 lb w/scope M-70 Classic/Benchmark/Edge in 300 WSM that is amazingly accurate.

    However, there is no way a 300 WSM can shoot as fast as a 300 Winny. It is all about case capacity, and the shape between these two cases doesn't have a huge effect on velocity. Further, comparing the numbers we get with our handloads in a couple of rifles really doesn't tell us much other than what we can get those rifles to do.

    The biggest question mark when we work up handloads is knowing pressure. I have personal knowledge of no less than five guys who have used Oehler 43s to test pressure. One of these fellows was an ballistics consultant for the US Army. They all agreed there really isn't a reliable way to tell when we are at maximum pressures. All of the conventional pressure signs: flattened primer, sticky bolt lift, case head expansion, etc; only tell us when we are well over maximum pressures. One particular lot of Remington brass tested to 80,000 PSI without showing and signs of pressure.

    That leaves us with the data the bullet and powder makers publish as our best reference for velocities obtainable for a given bullet/power/barrel length combination. This data has been scientifically obtained using high-end pressure equipment, and enough shots are fired to get statistically meaningful data.

    The 5th edition Sierra manual shows a 300 WSM with 190 and 200 grain bullets at 2900 FPS from a 24" barrel. It shows the 300 Winny shooting the same bullets at 3000 fps from a 26" barrel. We can add 50 fps to the shorter barrel, but the WSM is still falling short of the Winny. They don't show any data for a 240 grainer in the WSM, but they do show the 300 Winny getting 2800 FPS with a 240 grainer in a long throated rifle. There are many reasons why your own 300 Winny may have shot so slow, but it wasn't the norm.

    A general rule of thumb is to take the 1/4 of the difference in case capacity to get the increase in velocity. A 300 WSM holds 80 grains of water, a 300 Winny holds 90 grains of water. That is a 11% increase, and 1/4 of that is 2.78% At a MV of 3000 fps, 2.8% equals 84 fps. Now the 300 WSM will effectively have 1/2" more barrel length than a 300 Winny in the same length barrel, and that is worth nominally 25 fps. We are again at a 50 fps advantage to the 300 Winny.

    That is a 50 fps gain for the Winny in the Sierra manual, a 50 fps gain in standard calculations, and even a 50 fps gain with 240 grain SMKs in long throated rifles.

    Now without question we get more velocity per grain of powder with the WSM over the Winny, but that is true almost every time we downsize case capacities, and the converse is true when we add case capacity. Regardless, when a 300 WSM and a 300 Winny are both throated relatively the same, shot in the same length barrels with ammo loaded to the same pressures, the 300 Winny will be a little faster.
     
  8. Outlaw81

    Outlaw81 Member

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    Heya bub. I betcha I can beat a "winny " with ANY bullet. I'm not just speaking out my ***. Its experience. I guess u didn't get the part of my big thumper. Shorter cases with better neck angles always beat long and narrow. Its just physics.
     
  9. afp1

    afp1 Well-Known Member

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    I am not trying to be contentious, I just see it completely differently.

    I get what you are saying about case shape, I just don't agree that it is as big of a factor as you seem to think it is. Case capacity is the primary factor in determining velocity.

    I think you are getting higher velocities from your WSM because you are loading it to higher pressures than you are your winny. Been there, done that myself.
     
    Last edited: Jun 18, 2011
  10. Outlaw81

    Outlaw81 Member

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    Ur right it isn't as important. Pressure, twist, and barrel length are more so.
     
  11. MrMajestic

    MrMajestic Well-Known Member

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    After trashing a 7mm STW barrel in short order I am building a 7mm SAUM as we speak! It's the PPC syndrome. "They make the rockin' world go round"
     
  12. Ullrich

    Ullrich New Member

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    I too love the girls with big bottoms. I have a 270 wsm that has taken Pronghorn, and many deer. Haven't had a chance to soot elk, but would pull the trigger in a heartbeat. I have just picked up a 300 wsm and look forward to my first kill with it.
     
  13. Rocky Mountain

    Rocky Mountain Well-Known Member

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    The 338 norma magnum and the wild cats made from this case lives buy the same rules as the Short magnums you got to love them.
     
  14. tackb

    tackb Well-Known Member

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    I don't care , 100fps either way will make so little difference on target you would be better served practicing instead of arguing , it's hit's that count not kit!

    having said that i still read the whole thread (chuckling to myself!)