Going over data and not understanding. The powder I'm going to use is IMR 4198.
I note that in the trapdoor loads on the Hodgdon websight it shows a max of 36 grains for a 300gr cast boolit and 48 grains for a jacketed sierra 300. I calculated the case penetration for both at .415" loaded to the same OAL. For case volume it would seem identical. For the jacketed in the 1895 data it shows 57.2 grains.
So why with the case volume being the same are the max loads so different, radically different?
Different initial start pressures. Copper is harder than naked lead. So they build higher pressures.
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The max load with the cast bullet was based on the accuracy they achieved, not pressure. Accuracy fell off with higher speeds with this plain based bullet. You might be able to go faster with a gas checked bullet.
The jacketed load is based on maximum pressure for the Trapdoor Springfield (usually 28,000 CUP or PSI is accepted as maximum).
And these are going to be paper patched. They are actually .452 bullets patched up. I will eventually try some full throttle.
You should be fine up to the jacketed maximum load. Wear your shooting coat.
Oh man, 57 grain of 4198 will rattle the fillings out of your teeth!
Not going to be a bunch of them. I just want to kill a deer with a pure lead paper patched boolit and hit him hard.
Why, just because I want to.
The difference between the cast and jacketed loads is bullet strength. It will start gas cutting or stripping the rifling.
The different max between the two rifles is action strength.
They are two very different bullets. Cast lead vs. jacketed, different friction coefficients, different reactions to pressures, different bullet/alloy characteristics. If I saw loads with two different bullets to be identical, I would question the data!
My Anchor is holding fast!
You can not compare cast to jacketed bullets. Entirely different animals.
The solid soft lead bullet is undoubtably the best and most satisfactory expanding bullet that has ever been designed. It invariably mushrooms perfectly, and never breaks up. With the metal base that is essential for velocities of 2000 f.s. and upwards to protect the naked base, these metal-based soft lead bullets are splendid.
John Taylor - "African Rifles and Cartridges"
Forget everything you know about loading jacketed bullets. This is a whole new ball game!
Lead is soft....jacketed are hard. Takes less powder to get the lead boolit to reach the same velocity.
Use cast data with paper patched and plated , the jacketed data is for jacketed only .
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