45/70 for large bear... ammo?

memtb

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It’s been pretty well established by those that use big-bore handguns with cast bullets, John Linebaugh immediately comes to mind.....that high velocity with a wide metplat cast bullet actually hurts penetration!

Several years ago, John put on a gathering/ seminar of big game hunters (many with African Double rifles), where the big rifles competed with big bore revolvers in penetration tests. The handguns actually outperformed many of the African Big Bore Cartridges. I believe that a computer search could find the article covering the gathering/competition!

That said, I push my 430’s from my 45-70 to 1800 fps, which helps flatten my trajectory a little....in the event that I want to take a longer shot! Up close and personal.....it seems that I would just as well served with around 1200 fps! memtb
 
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Varmint Hunter

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What's interesting about the fact that solid bullets can have less penetration with lower impact velocities then higher speed impacts is that the higher speed bullet will slow down to the velocity of the lower speed bullet but still doesn't penetrate as far.
 

Dean2

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I had very little luck, accuracy wise, with hardcast lead bullets in my 1895SBL (JM). That is why I have concentrated on jacketed bullets and mono-metal bullets. The 350gr Swift A-Frame bullet has shot into .5"-.6" @ 100 yds on several occasions.

However, for the OPs needs, accuracy is fairly irrelevant.

With regard to the Garrett penetration information; it merely deals with penetration as a single component of terminal performance and does not address the speed of incapacitation. I believe that higher speed impacts set bodily fluids in motion and produce a shock wave through the body which accelerates incapacitation, sometimes significantly. Roy Weatherby was definitely onto something. So while a slower 45-70 bullet might penetrate deeper, a faster bullet of the same heavy construction might incapacitate faster.

That's just my 2 cents.
The effect of speed on incapacitation u are referring to is typically called Hydrostatic shock. That effect does not happen with projectiles trraveling less than 2500 FPS. It is why Roy Weatherby built the beast of cartridge that is the 460 Weatherby Magnum. I own one in a left hand action MKV. It produces awesome recoil, it is the only rifle I own that has a brake on it. Despite all the roaring, flame and drama it does not kill any faster than my 45-70 and I have shot a lot of bears with both. I have also shot bears with a 45-70 loaded from1100 FPS to 2000. I can tell you from experience the sweat spot is 1400-1500 fps for quick kills, reasonably flat trajectory, at least by 45-70 standards, and quick second shot recovery. My favourite load is a Hornady 350 grain RN over 3031 powder at 1500 fps.

5 quick shots at 100 yards over the hood of the truck.

HnJE62nl.jpg


3 shots, same 350 grain Horn RN traveling quite a bit faster. Accuracy is still fine.

l1NNAA1l.jpg
 

257WTBY

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Its in BC , guided elk trip. Ill be using a 340 wby on elk. If i get and elk i want to keep wandering around with my 2 buddies as they hunt. The 4570 would be for that.
I was in BC last year to hunt and the airline charged a per rifle surcharge on each rifle just FYI I didnt know till I was at the counter checking in.

Also you are right the Griz are everywhere in BC where we were. I literally saw grizzly everyday of a 10 day hunt. Where we were set up in spike camp the outfitter had dogs there to keep the bear out of camp. When the dogs start sounding off at 2 am it gets the blood pumping. The worst to run into is momma and a couple 500lb+ cubs running together. I carry a guide gun with buffalo bore ammo locally when we go berry picking and stuff for bears only ever seen a griz once here. When hunting i figure Im already carrying my 340 and the 250gr partition is gonna hit whatever really hard.

Post up some pics of your bull GOOD LUCK...
 

Lycanit

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Again, the projectile must transition through this " better penetration velocity" on the way to zero velocity. The same logic is used by people saying warm water freezes faster than cold water. Unless the projectile is deformed or other inconsistent medium is used all else being equal cavitation will still stop the rapid deceleration to the slower rate, at which point penetration would be as if fired from the platform at that velocity. Additionally the increased rotational speed would enhance depth as it imparts centripetal force to fluidic material. See the ARX and other solid none expanding projectiles that dramatically enhance this use of rotational energy to impressive effect. Without yaw or deformation physics demands conservation of energy and momentum.
 

Dean2

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The big problem with your "must work this way because of physics argument" is that there are multiple tests in more than one medium that proves it doesn't work like that in real life. Go do your own test, video it, and prove us wrong if you like, but sitting in your armchair pontificating isn't going to make me disbelieve what can be seen with my own eyes.

 
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Lycanit

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The effect of hydrostatic shock uses velocity as one variable of it's effect. Remember initial diameter of projectile and it's expanding surface area also play very important parts to the point, some people, believe are equal to velocity. The website ballisticstudies expands in depth on this for several modest velocity yet large caliber platforms, of course do as I have and perform the testing yourself.
 

Lycanit

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Long winded paper and accurate, but as I have stated.. physics demands all debts be paid!
 

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  • penetration0802.pdf
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Lycanit

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We are not allowed to pick the physics we like and disbelieve the ones we don't. I only speak about what I know. I have done the reading and the testing. I don't own an armchair. I will probably not change a single mind and most likely not many person's will have harm because of continued erroneous belief. Facts are still facts. Supercavatation is real and an effect not widely studied until the last couple of decades. Buy 3 blocks and shoot them with XYZ at 1200 and again at 1800. If there is no yaw or expansion then the greatest energy will have deeper penetration.
 

Lycanit

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This had tumbling in it but all did the same tumbling.. this is the exact measurement that we are discussing. The slower one penetrated less
 

Varmint Hunter

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The effect of speed on incapacitation u are referring to is typically called Hydrostatic shock. That effect does not happen with projectiles trraveling less than 2500 FPS. It is why Roy Weatherby built the beast of cartridge that is the 460 Weatherby Magnum. I own one in a left hand action MKV. It produces awesome recoil, it is the only rifle I own that has a brake on it. Despite all the roaring, flame and drama it does not kill any faster than my 45-70 and I have shot a lot of bears with both. I have also shot bears with a 45-70 loaded from1100 FPS to 2000. I can tell you from experience the sweat spot is 1400-1500 fps for quick kills, reasonably flat trajectory, at least by 45-70 standards, and quick second shot recovery. My favourite load is a Hornady 350 grain RN over 3031 powder at 1500 fps.

5 quick shots at 100 yards over the hood of the truck.

HnJE62nl.jpg


3 shots, same 350 grain Horn RN traveling quite a bit faster. Accuracy is still fine.

l1NNAA1l.jpg
Interesting - I've owned and extensively shot a LH 460 Wby myself. However, The only thing I shot with it was groundhogs. Penetration seemed adequate but recoil was well beyond "pleasant".

I used the 45-70 to take many bears but none were BIG bears, just black bears up to 300lbs. Although I've killed them with many different bullets my favorite is still the Speer 400 JFN bullet with a muzzle velocity of 1,700 ft/sec. They readily expand but have enough momentum to take them out the other side of every bear I shot.
 

Critter Picker

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I used a RCBS 405 FP GC ahead of H322 ( can't recall exact amount ) for a very large black bear. Punched through and kept on going . Bear went about 50 yards . Didn't know he was dead right away. Shooting a 1885 browning.
 

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