.45-70 Question

Discussion in 'Reloading' started by Savage13, Sep 5, 2012.

  1. Savage13

    Savage13 Member

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    Went shooting with my father the other day and he has a Pedersoli John Bodin rolling block rifle that has a 1 in 18 twist. He was shootin a black powder load ( triple 7) with a 405 gr bullet. @ 100 yards this load was key holling and the rounds were entering the target sideways ( could see a VERY clear cut out of the round). Did a lil research and from what I am seeing others are talking about the 405 gr bullets not being a good one for that rate of twist and to use a heavier bullet like the 500. Also found some "math equation" that seemed to agree with that. I was wondering if anyone here could also shead some light on to this situation. I know that the 405 round was the round the calvarey used for many years but further research lead me to find that the 405 were giving them issues in the longer barrels and that it was actually used in the shorter carbines. Please if any one here can help with this issue i would be trully appreciative.
     
  2. justgoto

    justgoto Well-Known Member

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    A Calculator for Barrel Twist Rate



    You'll need to know specifics like bullet length, muzzle velocity and such.


    My bet is on a dirty barrel. Every single time there is a key-holing post, the culprit turns out to be either heavy lead or copper fouling.


    Let us know what you find out.
     

  3. Greyfox

    Greyfox Well-Known Member

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    The 405 gr. Bullets were developed for the short barreled Trapdoor Springfields which had slow 1:22 twist barrels. The Buffalo Rifkes such as the Harps and Rolling Blocks had slower twists in the 1:18-1:20 range to handle the heavier 500+ grain. My Shilo Sharps 45-70 has a 1:18 twist. I shoot almost exclusively 525 gr.cast bullets and it's quite accurate. I have also shot Hornady 400 gr. Jacketed bullets in it and while the twist was fast, it shot them well with no key holing. An important factor if using 405 gr would be to make sure "hard cast" lead bullets have at least 1:20 tin content. Soft lead will strip in fast twist barrels. Also, if your bullets are cast, you need to check the diameter sizing. The fit has to be right and the molds, and finished bullets have come in varied sizes. If you want a great reference for shooting these rifles and how to load for them get, "Shooting Buffalo Rifles of the Old West" by Mike Venturino.
     
  4. RT2506

    RT2506 Well-Known Member

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    Your problem is most likely using the wrong bullet lube. It takes a special bullet lube made for black powder to KEEP THE FOULING SOFT. SPG or Lyman Gold are two good ones. I make my own out of 50 % bees wax 40% olive oil and 10% STP oil treatment by volume. Melt in a double bowler and mix well. Black powder and equivalent stuff leaves a HARD fouling in the grooves and causes the lead bullets to strip out of the rifling and they will key hole. I have a 18" twist Sharps 45-70 and shoot Lyman #457193 405 gr style bullets that actually come out 418 grs from straight wheel weights with outstanding accuracy with true black powder FFG and Cartridge grade and also Pyrodex Select. Fill a case using a 24" or longer drop tube to let the powder settle and stack up good until you reach enough to allow you to place a 30 thousands thick Walters wad on the powder and then compress the powder about 1/10 of an inch with a piece of dowel rod and final seating of the bullet. Once you find this amount then you can weigh your charges to be consistent. Black powder is not like smokeless. The exact weight is not all that important but volume of space filled is very important. It needs to be compressed some to shoot well also. Use a hot primer like Fed 215 also. If you want to find out if it is your bullet that it the problem get you some Accurate XMP 5744 smokeless powder and use 28 grs under your 405 gr bullet. If it key holes it is the bullet. If you want a good 500 gr bullet the Lyman #457125 is a good one.
     
  5. 300RUM LNGRNGE

    300RUM LNGRNGE Active Member

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    I know this is a old thread, and I apologize for but it seems that this would be the place to have my questions answered.
    I have a sharps 45-70 . 32 inch 1:18 twist. Want to shoot BP and have been doing a lot of research on the subject.
    What I don't understand is that with a 500 gr bullet and a .060 cardboard wad, there is a need to compress the powder.
    My understanding is that the only difference between FFg powder and FFFg powder is granule size.
    Everything I read on load data is compressed FFg run down through a 24 inch drop tube. Upon compressing FFg , are we not smashing granule size?
    In loading 70ish grains of FFFg powder, this will also need to be slightly compressed, but not as much since it settles in the casing lower.
    In compressing FFg so far, is it not getting compressed into FFFg and tighter?
    Why then is everyone using FFg?
    I have heard that FFFg will have higher pressure, but black powder is black powder. So wouldn't 70 grain of either by weight, not by volume, produce the same pressure especially when compressed to the same volume?
    I am not trying to say that everyone else is wrong, nor am I trying to re-invent the wheel, just trying to wrap my brain around this.
     
  6. Greyfox

    Greyfox Well-Known Member

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    Re: .45-7

    I think it is very important to realize that black powder loading and ballistic performance is generally defined by loading volume as opposed to weight. Whether using a drop tube or not the volume of ffg vs ffg will be different at a given weight and you will not fit the same amount by weight in a fixed space when loading to full case capacity. Even compressed, there is less air space between the smaller granules of fffg and therefore the pressure dynamics and burn rates are different IMO.
     
  7. RT2506

    RT2506 Well-Known Member

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    When learning about Black Powder loading it pays to learn from around 200 or so years of experience. Mainly FFFG does not shoot as accurately as FFG or cartridge grade in big cases like the 45-70. Black powder must be compressed a little to really work well. Velocity over the speed of sound will not be as accurate at long range as velocity under the speed of sound. Keeping those 500+ gr bullets around 1100 fps muzzle velocity or a little under is what you want. The fellows that shoot BP silhouette have really got it down to a science. Many have tried to re-invent the wheel but usually find out that the round one usually works best. :D
     
  8. Trickymissfit

    Trickymissfit Well-Known Member

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    I certainly glad you made this post Sir! At one time I had a friend that would have bailed me out with these issues. He was known to be one of the very best black powder shooters in North America. I lost contact with Russ years back. He shot several Pedersoli's as well as Sharps and some ancient stuff. I do remember him telling that with the Pedersolis that fit of the bullet to the bore was extremely critical.
    Want to say .001" to .0015", but may have even been .002". Russ used very hard lead bullets from his own molds. Sized them with custom honed bushings. His bullet lube stunk like catfish bait! He also had a red colored lube he used for certain guns.
    gary
     
  9. 300RUM LNGRNGE

    300RUM LNGRNGE Active Member

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    Will these low velocities still maintain enough energy to kill Bison at 4-500 yard distances?
     
  10. Greyfox

    Greyfox Well-Known Member

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    Put a 526 gr lead slug with 10-20% tin in the right place and it certainly will.
     
  11. RT2506

    RT2506 Well-Known Member

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    In 1873 when the US Army was doing testing of the trapdoor Springfield 45-70 the load was 70 grs black powder and a 500 gr bullet that did between 1100 and 1200 fps. It would penetrate a 6" diameter pine log and go over a foot into the sand behind it at 1000 yards.
    I once shot a deer with my Sharps 45-70 at 111 yards that was facing me with a Winchester case full of FFG compressed about 1/10th inch with the Lyman 405 flat nose that actually weighed 418 gr out of my mix which would do 1400 fps. Between the time that I fired the shot and the bullet got to the deer it started putting it's head down. The bullet struck it right in the forehead between the eyes. It made saw dust out of the neck vertebra then deflected and came out right behind the left shoulder. Then the bullet angled down and completely shot off the left back leg just above where the knee is. The bullet then hit the hard packed logging path and went about 5 yards looking like a mole under the ground. It came out of the ground and went through a pine tree about 4 inches in diameter jerking a slab the size of my hand off the back. I lost where it went from there. Yep, a freight train don't have to be going too fast to smash through a lot of stuff. :D