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Old March 21, 2018, 10:48 AM   #26
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Quote:
Originally Posted by ammo.crafter
Concerned about leading or not grabbing rifling, match BHN to velocity.
So a shooter has two guns in the same chambering shooting the same lead bullet load. One has a barrel 40% longer than the other. Which one's velocity does he match the BHN to?

As described in detail by Richard Lee in Chapter 10 (p.129) of the second edition of his book Modern Reloading, it is peak pressure that determines when bullet distortion starts to occur for a given BHN. Lee shows that because the Brinnel testing method can be reduced to PSI of indentation force, if your peak chamber pressure never exceeds 1422 psi times the BHN number, regardless of what final velocity you get, the bullet will not undergo pressure distortion. That's very hard compared to what many use in rifles, and there are examples of a bit of deformation actually being beneficial, as when recovering bore obturation after passing through a bore constriction. Elmer Keith, for example, developed the 44 Magnum with BHN 11 bullets, but his pressures were roughly 2½ times higher than Lee's distortion point. So it's not an absolute limit, but one that tells you where bullet distortion will start, and you then have to determine how much of a factor that is for you. For the BHN 12, 16, 18, and 21 bullets commonly advertised, these pressures would be 17,064 psi, 22,752 psi, 25,596 psi, and 29,862 psi, respectively.

The 94:3:3 alloy, if not heat treated, is estimated by the Cast Boolits site calculator to be BHN 12.2. That expanding bullet can't be too hard in order not to be too brittle, but just under 17,350 psi is where it will start to distort from pressure and is where you want to watch for an accuracy decline or a metal fouling increase. It's a pretty low number for a rifle, and even a starting load of Trail Boss makes more pressure, so some distortion is likely unavoidable. About the best you can do is watch for accuracy deterioration as you work the load up.


Quote:
Originally Posted by jamaica
Please do not do this. The 30-30 needs .308 bullets.
As already explained, this is not true of cast bullets. Even for copper jacketed bullets, the SAAMI standard calls for bullet diameters of .306" to .309". Softer lead can easily be funneled into a smaller bore. Indeed, many 45 Colt guns from the 0.454 to 0.451 transition period have 0.451" barrels with 0.456" chamber throats, and bullets at the full 0.456" often shoot most accurately in these guns. Empirical testing has shown many lever guns like lead bullets at 0.002" over groove diameter for best accuracy.
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Old March 21, 2018, 11:29 AM   #27
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Quote:
Originally Posted by Unclenick View Post
The 94:3:3 alloy, if not heat treated, is estimated by the Cast Boolits site calculator to be BHN 12.2. That expanding bullet can't be too hard in order not to be too brittle, but just under 17,350 psi is where it will start to distort from pressure and is where you want to watch for an accuracy decline or a metal fouling increase. It's a pretty low number for a rifle, and even a starting load of Trail Boss makes more pressure, so some distortion is likely unavoidable .
That is pretty low. What about the gas check as a means to prevent or limit leading?

Pressures for potential load using 4895. This is for jacketed bullets.
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Old March 21, 2018, 12:12 PM   #28
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Lyman's Cast Bullet Handbook lists loads using a 10:1 alloy with gas checks and they publish velocities up to a little more than 2,000 fps at pressures just over 40K.

The 10:1 alloy is a little softer than the Missouri bullet is.

They do not list IMR 4895 or H4895 as a usable powder.

I would normally use IMR 4198 or RL 7.

I think what you have would be doable within limits. I think the 27.0 gr load using H4895 might be a good place to start and end. You could drop the charge weight a couple of grains and have a workable load to start and then check for problems.
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Old March 22, 2018, 11:39 PM   #29
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I don't think I saw a velocity that you intended to use. I think an ordinary pig is going to die when hit by a cast 150 grain bullet at the normal velocity attained by a 30 commie. I'm not sure that the wide open point is a great idea for that particular target, I think that a plain old SWC HP will work just fine. The bullet is designed for rapid opening. That may not work so well at high velocities against those things, but I don't really know. I suspect that you will get full penetration even if it does expand.

Did that dealer have a list of suggested loads and velocities? if so, that is what your answer is.
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Old March 23, 2018, 09:26 AM   #30
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I was about 5 years old, I got home and my mother wanted to know where I had been. I informed her I spent the morning at that place where they kill pigs and cows. She wanted to know how they did it so I filled her in. I told her they killed them with big hammers etc.. After that I had to scratch the packing house off of my list of places to visit. About 13 years later I delivered a brick of 22 long ammo to another packing house.

One day on her way to work she stopped at a rail road crossing and waited for a train. In all appearance it looked like my two older brothers were running the train and they did not get into as much trouble as I did for visiting the packing house.

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Old March 24, 2018, 11:45 AM   #31
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As mentioned, regardless of whether the kinetic energy of a bullet is 100% retained in a body or passes through, it is simply not sufficient enough to make a big difference. Because of Newton third law, a bullet capable of exercising enough energy to significantly affect a body, will have a reverse and equal reaction against the shooter.
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Old March 24, 2018, 01:11 PM   #32
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kinetic energy is a lousy measure of what physiological damage or injury can occur, at the normal levels of shooting. on a macro scale, a piece of #12 bird shot at near light speed may not even be felt. thats a lot of ke. otoh, a 20 pound hammer at maybe 50 fps, oh, my, that's going to leave a bruise. we bring those levels down to 1-3k fps, 1-500 grains, and using them on flesh and bone, and things are less consistent, we have to add in other factors like bullet design and performance and target material.

if you test out those first examples on an anvil, that piece of bird shot would release energy on a relativistic scale, enough power to blow an entire county off of the map, possibly. That hammer is going to ring like heck.
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Old March 27, 2018, 01:05 PM   #33
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"I thought that a cast bullet is ok and some seem to prefer a bit oversized? "

It is pretty standard to use a cast bullet that is a bit larger that a jacketed bullet is. If shooting .308 in jacketed, then .310 - .311 in cast would be suitable.
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Old April 2, 2018, 04:08 PM   #34
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Quote:
Originally Posted by black_hog_down View Post
Thank you for pointing that article out. I was not familiar with the TKOF, but when I looked at the equation, it made no sense at all from a physics perspective.
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Old April 2, 2018, 06:15 PM   #35
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Quote:
Originally Posted by black_hog_down View Post
http://www.chuckhawks.com/taylor_KO_factor.htm

Quote:
Thank you for pointing that article out. I was not familiar with the TKOF, but when I looked at the equation, it made no sense at all from a physics perspective.
Actually, it makes more sense than the standard energy formula, since it takes bullet diameter into consideration and somewhat diminishes the degree to which velocity is considered.

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Old April 2, 2018, 06:19 PM   #36
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What do you think about this wide flat HP bullet?

Quote:
Originally Posted by nvcnvc View Post
Thank you for pointing that article out. I was not familiar with the TKOF, but when I looked at the equation, it made no sense at all from a physics perspective.


In addition to the article, TKO was intended to compare effectiveness in knocking out elephants shot in the head since they have thick shock absorbing bone sponge. It had no intended purpose for body shots or small/medium game.

That hasn't stopped people from grossly misapplying it. Other elephant hunters such as Bell favored deep penetrating bullets with precision placement in the brain and used heavy for caliber solid bullets in 6.5 and 7 mm among others.
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Old April 2, 2018, 07:28 PM   #37
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Onespeedbiker,

Newton's third law makes the momentum equal and opposite, not energy. Suppose you suspend a 10 pound rifle from strings and shoot a 200-grain bullet from it at 2600 fps. The bullet is 350 times smaller in mass than the rifle, so when the same force accelerates the two in opposite directions for the same amount of time, the rifle ends up going 350 times slower. About 7.4 fps. At that velocity the gun's recoiling energy is about 8.6 ft-lbs. But the bullet's energy at 2600 fps is just a hair over 3000 ft-lbs.

That difference in recoil energy and bullet energy is the main reason why the bullet is much more distructive to the target than recoil is to the shooter. The fact the cross-sectional area of the bullet is smaller than the butt contact area is too small a difference to account for it. That's less obvious when you speak of a pointed bullet and a wide rifle butt plate than it is when you speak of a .22 rimfire fired from a North American Arms mini-revolver with its tiny bird's head grip.
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Old April 2, 2018, 07:39 PM   #38
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Hmm, has anyone here done any testing on the effectiveness of a slower large caliber bullet .vs a faster smaller caliber bullet with a higher calculated energy number? I've killed several deer (which do not fall into the elephant class) with body shots with both the .357 Magnum with a much faster bullet and higher calculated energy number, and the .45 Colt with it's lumbering heavy bullet and lower calculated energy number. No comparison - the .45 Colt put them down with authority. Anybody ever seen what a slow moving .70 caliber 12 gauge slug does with flesh and blood? This is why I say the mathematical energy calculation which over emphasizes velocity and totally disregards caliber has no correlation with actually killing power. Just MHO.

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Old April 2, 2018, 08:37 PM   #39
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Black-hog-down,

You can fire much softer bullets than you'd think. Elmer Keith used first 20:1 lead:tin, and then 16:1 in developing the 44 Remington Magnum. Both are pretty soft compared to alloys with antimony. If you add a gascheck it will prevent gas cutting and deformation of the base. That's critical for accuracy. The nose can still slump under the acceleration, but its less important than the base is to accuracy as long as it doesn't go too far.
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