nanker13
Member
When using the same bullet and powder weight doesn't a lead bullet produce more pressure and velocity? Is there a general % one should back off when using lead vs jacket of the same weight bullet?
Thanks.
Thanks.
Lead vs jacketed
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Dudedog
Contributing Member
I have found in general yes, less for lead than jacketed, plated is somewhere between the two.
However some manafactures web sites data show almost exactly the same.
For example Hodgdon .45 APC HP 38 230 almost exactly the same except lead has a .1 gr Higher start charge. ???? (also shows less pressure and vel for lead with the same charge)
If you look at the data for 125 in 9mm HP38 is .5 gr less to start .4 less for Max. The range may be different but in 9 they show less for lead than jacketed for most listed powders.
However some manafactures web sites data show almost exactly the same.
For example Hodgdon .45 APC HP 38 230 almost exactly the same except lead has a .1 gr Higher start charge. ???? (also shows less pressure and vel for lead with the same charge)
If you look at the data for 125 in 9mm HP38 is .5 gr less to start .4 less for Max. The range may be different but in 9 they show less for lead than jacketed for most listed powders.
spitballer
Member
Interesting thread and worth reading. This subject is applicable to rifle bullets, as well. Not everyone uses FMJ's!
It is likely the jacketed will give more pressure and less velocity, while the lead will give less pressure and more velocity, due to friction. Lead gives much less friction.
In general of course.
No, use lead data, or a great deal of experience, whichever one you have the most of. I just use lead data.
Sunray
Member
A cast bullet and a jacketed bullet are not the same thing. You cannot use the same powder load. If you do, you'll get leading. Leading is caused by driving a cast bullet too fast.
There are several things that can cause leading, to slow, to fast, to small, not enough pressure, too much pressure, too soft, too hard, etc, etc. 
But, as posted, the data is different, and there is no set % you can adjust between the two.
But, as posted, the data is different, and there is no set % you can adjust between the two.
41 Mag
Member
Walkalong is giving you the straight scoop on the lead verses jacket.
Listen and heed his suggestions and advice, it will pay off.
Listen and heed his suggestions and advice, it will pay off.
spitballer
Member
I know better than to argue with Walkalong and pistol ballistics surely differ from rifle ballistics, but aren't bullet characteristics largely dependent on applied pressure?
For example, I understand that lead will produce less friction against a steel bore vis-à-vis copper, I have no trouble with this. But isn't that friction less of a factor if pressure is kept low enough to keep a jacketed bullet from squishing against the bore?
Presumably a low-pressure round is just not a practical for handgunners who need high-velocity, accurate, dependable self defense with a short-barreled firearm in a hurry, fouling or no fouling? No argument here, either!
Hope I haven't detracted from or altered focus of this interesting and important handgun-related thread, thanks.
For example, I understand that lead will produce less friction against a steel bore vis-à-vis copper, I have no trouble with this. But isn't that friction less of a factor if pressure is kept low enough to keep a jacketed bullet from squishing against the bore?
Presumably a low-pressure round is just not a practical for handgunners who need high-velocity, accurate, dependable self defense with a short-barreled firearm in a hurry, fouling or no fouling? No argument here, either!
Hope I haven't detracted from or altered focus of this interesting and important handgun-related thread, thanks.
I have found that in general a jacketed start load will push a cast bullet at the same velocity as a jacketed bullet at max load. When I have only jacketed data for a lead bullet of particular weight I'll reduce the max load by 20% to use as a start and use the jacketed start or 10% reduction as the maximum lead load.
GP100man
Member
Lead boolits of the correct size for the bore (generally .001-2" over bore size) seal the bore & keep the pressure behind it , example 38/357 I size to 3585-359, where as jacketed bullets are 357 & they let a little pressure vent by.
Now , If you push lead boolits past the point of the alloys tenstile strength to grab the rifling & it skids & tears a path on the driving bands it`s called gas cutting & this will lead a barrel up in just a few shots .
The above is magnified 10 fold if the boolits are undersized !!
Now , when I consider a load , say for hunting I use boolits on the heavy side , again 357 I use a 175 gr. swc & a slow powder ,example H-110 or 2400.
This gives the boolit a slow start & builds pressures over a longer curve than lets say Bullseye which is a fast powder & would have a very sharp pressure curve, thus giving less FPS over the chrony.
I hope this gives ya more insight on your original question.
GP
Now , If you push lead boolits past the point of the alloys tenstile strength to grab the rifling & it skids & tears a path on the driving bands it`s called gas cutting & this will lead a barrel up in just a few shots .
The above is magnified 10 fold if the boolits are undersized !!
Now , when I consider a load , say for hunting I use boolits on the heavy side , again 357 I use a 175 gr. swc & a slow powder ,example H-110 or 2400.
This gives the boolit a slow start & builds pressures over a longer curve than lets say Bullseye which is a fast powder & would have a very sharp pressure curve, thus giving less FPS over the chrony.
I hope this gives ya more insight on your original question.
GP
CLP
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"A cast bullet and a jacketed bullet are not the same thing. You cannot use the same powder load. If you do, you'll get leading. Leading is caused by driving a cast bullet too fast."
Not necessarily so. Could be caused be driving a bullet too fast, or too slow. Using too soft of an alloy, or too hard of one. Using too hard of a lube, or too little. Or from the barrel being unlapped or from other dimensional inconsistencies. Like I said, the Lyman book is a good read. Also the PDF book by glen Fryxell.
Not necessarily so. Could be caused be driving a bullet too fast, or too slow. Using too soft of an alloy, or too hard of one. Using too hard of a lube, or too little. Or from the barrel being unlapped or from other dimensional inconsistencies. Like I said, the Lyman book is a good read. Also the PDF book by glen Fryxell.
Lead is softer and forms to the bore size and rifling much easier than a jacketed bullet which means less pressure is required to force it down the bore. Leading is caused by several factors. A hot powder/high flame temp can melt the lead and cause fouling. Driving the bullet too fast can also cause it. A gas check can solve these problems.
Sizing a lead bullet too big for the bore will also cause it and also raise pressures.
Sizing a lead bullet too big for the bore will also cause it and also raise pressures.
Walkalong said:
Pressure or Force to physically move the bullet through the bore is different than "Chamber Pressure".
If you look at load data that has both lead and jacketed bullets you will see that often times the lead bullet generated more "Chamber" pressure the same same weight Jacketed bullet.
http://data.hodgdon.com/cartridge_load.asp
http://www.ramshot.com/wp-content/up...ec_1-23-14.pdf
Now if the OP was talking about the amount of force/pressure to physically push a bullet through a bore then, "yes" more force required for jacketed vs Lead. If the OP was talking about "Chamber" pressure then according to Pressure Tested Load data then the answer is "Yes' for this load and "No" for that load, in other words "Maybe.
One theory why Jacketed bullets produce less "Chamber" pressure is "obturation".
A properly sized lead bullet seals off the bore and traps the gasses behind the bullet. A harder jacketed bullet does not seal the bore as well or as completely and gasses can escape past the bullet thus reducing "Chamber" pressure.
Take a look at Hornady #7 45 ACP data for example.
230gr FMJ COL = 1.230. This bullet measures .651 inches.
230gr Lead RN = 1.245. This bullet measures .640 inches.
So the Jacketed bullet is .011 longer and is seated .015 deeper, for a total of .026 deeper.
Data.
N-340 Lead, Max = 6.6gr. Jacketed. Max = 6.7gr.
Even with the .026 deeper the jacked bullet used more powder to reach similar pressure as lead.
Clays Lead, Max = 6.2gr. Jacketed. Max = 6.4gr
Even with the .026 deeper the jacketed used more powder.
231 Lead, Max = 6.2gr. Jacketed. Max = 5.7gr
Here the Lead bullet with less seating depth used more powder. Maybe due to COL, maybe due to the lead bullet.
Unique Lead, Max = 6.3gr. Jacketed. Max = 6.1gr
Again we have more powder with lead than we do with Jacketed.
We can also look at Speer #13. They list their 230gr L-RN at 1.270 COL and their Jacketed 230gr TMJ at 1.260. I do not have the length of the L-RN compared to the TMJ, but of the five(5) powders that are used for both the Lead bullet used significantly less powder than the Jacketed TMJ.
All we have to go on as handloader is load data. Theories are great and often times helpful, but when they conflict with actual pressure tested data, it's best to follow the data and not the "Theory".
So far I have seen no evidence here that Lead bullets build less pressure than jacketed. I have seen lead more, lead less and lead the same. I have seen lead bullet seated deeper producing more pressure, less pressure and again the same pressure.
This is from John Barsness of Handloader Magazine.
"Normally a lead bullet of the correct diameter and hardness produces more pressure with the same powder charge, because it does seal the bore better."
More data that shows Lead produces more Chamber pressure.
This is also from John Barsness.
Here's somedata from Hodgdon's website:
.44 Magnum handgun--
240 cast/ 22.0 IMR4227/ 33,300 CUP
240 jacketed/ 22.0 IMR4227/ 28,400 CUP
.38-55 rifle--
250 cast/ 27.0 H322/ 27,000 CUP
255 jacketed/ 27.0 H322/ 25,500 CUP
250 cast/ 24.0 IMR498/ 36,200 CUP
255 jacketed/ 24.0 IMR4198/ 31,400 CUP
Please not that even though the jacketed bullet in the .38-55 weighs 5 grains more, pressures are less with the same powders charges. And in all the above instances, the STARTING load with jacketed bullets is the MAX load with cast bullets.
I took some time and read through my Lyman 48 and Hornady #7, looking for any information on bullet composition and pressure. Hornady had nothing. Lyman had a small paragraph in their, "Mystery of Pressure" section page 99.
It basically said bullets are not created equal and can have a huge affect on pressure. Length, bearing surface, bullet hardness and composition can all play a role in chamber pressure. Hard (jacketed) bullets can be sensitive to bore diameter and rifling style and cause higher pressure.
It went on to say, Don't assume any rule of thumb to be true, especially this one. Sometimes a "hard" bullet shows lower pressure while the softer bullet shows higher pressure. A soft bullet may cause higher pressure because the bullet is so malleable that the sides will push hard against the bore when high pressure is exerted on the base.
It ended with this, So the rule is simply this, "assume nothing".
It basically said bullets are not created equal and can have a huge affect on pressure. Length, bearing surface, bullet hardness and composition can all play a role in chamber pressure. Hard (jacketed) bullets can be sensitive to bore diameter and rifling style and cause higher pressure.
It went on to say, Don't assume any rule of thumb to be true, especially this one. Sometimes a "hard" bullet shows lower pressure while the softer bullet shows higher pressure. A soft bullet may cause higher pressure because the bullet is so malleable that the sides will push hard against the bore when high pressure is exerted on the base.
It ended with this, So the rule is simply this, "assume nothing".
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