moooose102
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i have a question, all things being equal (same brass, primer, powder, bullet weight), is there a pressure difference between straight lead bullets and copper jacketed bullets? and is the velocity going to be different?
pressure difference
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ranger335v
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Assuming you are thinking of handguns? Actually, there should be very little difference atributable to the difference in bullets.
Even the hardest alloyed cast bullets are easily maliable at the pressures involved. The jacketed stuff almost always has thin, soft jackets and soft, unalloyed lead cores that also take to the forcing cones and lands easily. There is not a lot of difference to the weapon for either type.
When either type bullet has entered the bore and traveled it's own length it is fully "sized" to match that bore so the rest of its travel is easy.
Even the hardest alloyed cast bullets are easily maliable at the pressures involved. The jacketed stuff almost always has thin, soft jackets and soft, unalloyed lead cores that also take to the forcing cones and lands easily. There is not a lot of difference to the weapon for either type.
When either type bullet has entered the bore and traveled it's own length it is fully "sized" to match that bore so the rest of its travel is easy.
"Actually, there should be very little difference atributable to the difference in bullets."
Not correct.
Jacketed bullets (not just thinly plated) require significantly more force to engrave into the rifling.
This occurs in some cartridges right around the peak pressure spot produced as the powder burns.
A load near maximum with a lead bullet can easily go OVER maximum with a jacketed bullet of the same weight and shape.
Not correct.
Jacketed bullets (not just thinly plated) require significantly more force to engrave into the rifling.
This occurs in some cartridges right around the peak pressure spot produced as the powder burns.
A load near maximum with a lead bullet can easily go OVER maximum with a jacketed bullet of the same weight and shape.
rcmodel
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Bore friction is the culprit, not how soft or hard the bullets are.
Lead based Babbitt alloy used to be used for bearing blocks in machinery and rod & crankshaft bearings in car engines.
Lead is very slick stuff when a little grease or oil is added to lubricate it. (Bullet lube)
Copper is slightly less effective as a bearing material to begin with.
And jacketed bullets are forced through the barrel dry, without a hint of lubricant.
That all results in more bore friction, and more pressure from jacketed bullets with like loads.
rcmodel
Bore friction is the culprit, not how soft or hard the bullets are.
Lead based Babbitt alloy used to be used for bearing blocks in machinery and rod & crankshaft bearings in car engines.
Lead is very slick stuff when a little grease or oil is added to lubricate it. (Bullet lube)
Copper is slightly less effective as a bearing material to begin with.
And jacketed bullets are forced through the barrel dry, without a hint of lubricant.
That all results in more bore friction, and more pressure from jacketed bullets with like loads.
rcmodel
Charge weights being equal the lead bullet, be it hard cast or swagged will shoot faster than a jacketed bullet.
Lead bullets usually seal in the bore better so pressures can increase, this is one of the reasons lead loads are usually LESS than jacketed along with high velocity leading problems showing up with lighter charges.
From my informal testing with the .357 mag, I've found that most powders will deliver a lead bullet at the same velocity as an equal weight jacketed using 1 less grain of powder.
Lead bullets usually seal in the bore better so pressures can increase, this is one of the reasons lead loads are usually LESS than jacketed along with high velocity leading problems showing up with lighter charges.
From my informal testing with the .357 mag, I've found that most powders will deliver a lead bullet at the same velocity as an equal weight jacketed using 1 less grain of powder.
ranger335v
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I was clearly speaking to jacketed bullets, not copper plated.
Yawl may be right. But my chronograph agrees with me. I find no statistical difference in velocities between them in my .357, .44, and .45 ACP when the bearing surface lengths are the same or nearly so.
Yawl may be right. But my chronograph agrees with me. I find no statistical difference in velocities between them in my .357, .44, and .45 ACP when the bearing surface lengths are the same or nearly so.
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