Load reduction for lead vs jacketed of the same weight?

[Rule3]

I know that "rule of thumb" is not a exact way to go about things, but is there a general percentage to lower the amount of powder when comparing a lead bullet to a jacketed of the same weight?
Lead usually requires less powder, yes?
So if there is no load data for a lead bullet do you just use the start load of a jacketed of the same weight?

[cmort666]

Originally posted by OCD1:
I know that "rule of thumb" is not a exact way to go about things, but is there a general percentage to lower the amount of powder when comparing a lead bullet to a jacketed of the same weight?
Lead usually requires less powder, yes?
So if there is no load data for a lead bullet do you just use the start load of a jacketed of the same weight?

Starting loads tend to be VERY mild. You won't have overpressure, but be careful of squibs.

[Cary]

Originally posted by OCD1:
I know that "rule of thumb" is not a exact way to go about things, but is there a general percentage to lower the amount of powder when comparing a lead bullet to a jacketed of the same weight?
Lead usually requires less powder, yes?
So if there is no load data for a lead bullet do you just use the start load of a jacketed of the same weight?

That is what I have been doing and it seems to work for me. I will usually run some of those first loads over my chronograph to get an indication of where I am at concerning bullet speed. If all looks good I will adjust my powder charge from there.
Cary

[Rule3]

Yes, that sounds logical but unfortunately I do not have a chroo. Maybe next Christmas.

[Snapping Twig]

Using cast bullets .001 over bore size, typically after working up for safety reasons, all else being equal, I use the same powder charge as a jackedted bullet and take the extra velocity (@ 100fps) as an end result with lead.

[HAWKEYE10]

I HAVE THE SAME PROBLEM. I LOOK AT THE SAME WEIGHT JACKETED OR A CLOSE WEIGHT CAST. IF LOADING FOR A REVOLVER I LOAD LOW TO MEDIUM,IF LOADING FOR A SEMI AUTO I WILL LOAD 25RDS MEDIUM AND TEST FIRE.I WILL CONTINUE UNTIL I GET THE SLIDE TO CYCLE. I DON'T LOAD TO MAX. AND NEVER NEVER OVER MAX. IN MY OPINION THESE COMPANY SHOULD PUT OUT LOAD DATA BUT THEY DON'T.
DON

[Steve C]

Generally I've found a 20% reduction of a jacketed load gives a good start point for a lead bullet of the same weight and a load at 10% reduction or the start load for a jacketed bullet usually achieves the same velocity with lead as the jacketed bullets maximum velocity.

[ArgMauser]

What is your goal: achieving combat effectiveness or achieving target accuracy?

If you are worried about excessive pressure in a high-speed combat load, then you can rest assured that pressure will be less with a lead bullet than with a jacketed bullet over the the same powder charge because the barrel friction is less with a lead bullet than with a jacketed bullet.

If you're working up an accuracy load, use less powder with lead than with jacketed bullets because the softer lead will not hold the rifling as well as the jacketed bullet will at higher velocities.

The above holds for typical velocity ranges, biut be careful at the extremes of low and high velocity. At very low velocity, a jacketed bullet may stick in the barrel (fail to exit), while at very high velocity, a lead bullet may expand when entering the forcing cone--possibly cracking the forcing cone.

[Rule3]

Originally posted by Steve C:
Generally I've found a 20% reduction of a jacketed load gives a good start point for a lead bullet of the same weight and a load at 10% reduction or the start load for a jacketed bullet usually achieves the same velocity with lead as the jacketed bullets maximum velocity.

Sorry I am a bit lost on that??

I understand the start load of jacketed achieves about the max velocity of jacketed with lead.
Is your 20% reduction of the maximum jacketed value??

I am only looking for mild target loads for 40 sw. So if my load data for 180gr fmj is 4.1. gr start would I use this also for 180 gr lfn.?

[H Richard]

I refer to my "Cast bullet handbook" by Lyman for lead loads. For swagged bullets, I refer to the mfg's data.

[Rule3]

Originally posted by H Richard:
I refer to my "Cast bullet handbook" by Lyman for lead loads. For swagged bullets, I refer to the mfg's data.

Do you by chance have data for a a 40SW 180gr cast using HP38 or Win 231??

[OKFC05]

"Rules of thumb" are generalities that are usually but not always true.

The safe way is to use data from at least one, preferably two, loading manuals.

There are some nasty surprises lurking out there that can damage your gun or you.

[Rule3]

Originally posted by OKFC05:
"Rules of thumb" are generalities that are usually but not always true.

The safe way is to use data from at least one, preferably two, loading manuals.

There are some nasty surprises lurking out there that can damage your gun or you.

Very true and I agree, but what does one do when the data for a specific lead bullet can not be found?
This is why I posted a request here.

The "closest" I have is from Lyman for a 175 gr lead bullet.

[OKFC05]

You REALLY need to convince Mama she needs a chronograph for her birthday........

[fredj338]

Originally posted by OKFC05:
"Rules of thumb" are generalities that are usually but not always true.

The safe way is to use data from at least one, preferably two, loading manuals.

There are some nasty surprises lurking out there that can damage your gun or you.

There in is the problem. There are so many diff. styles & variations of lead bullet, you just aren't going to find printed data. I have found that a sim. bullet profile & wt. bullet in lead, needs a 5%-10% reduction to achieve sim. vel. as a jacketed bullet. It will vary a bit w/ the speed of the powder, but that is how it seems to work for me over my chronograph.

[bluetopper]

Do you by chance have data for a 40SW 180gr cast using HP38 or Win 231??[/QUOTE]

The closest I can come to what you want is with a 175gr cast lead bullet. My Lyman manual shows:
a starting charge of 4.3gr of 231 at 863fps and a max charge of 5.8gr at 977fps.....seated at 1.125" OAL

[Rule3]

Originally posted by parisite:
Do you by chance have data for a 40SW 180gr cast using HP38 or Win 231??

The closest I can come to what you want is with a 175gr cast lead bullet. My Lyman manual shows:
a starting charge of 4.3gr of 231 at 863fps and a max charge of 5.8gr at 977fps.....seated at 1.125" OAL[/QUOTE]

Thanks, I have that manual also and is what I am going with. I'll load some up at 4.3 grs and see how they function.

[Steve C]

Originally posted by OCD1:

What I'm saying is that a start load or 10% reduction off a jacketed load should be considered maximum for lead. Therefore the start load for a lead bullet would be another 10% reduction off that maximum which is a 20% reduction from the jacketed data.

Sorry I am a bit lost on that??

I understand the start load of jacketed achieves about the max velocity of jacketed with lead.
Is your 20% reduction of the maximum jacketed value??

I am only looking for mild target loads for 40 sw. So if my load data for 180gr fmj is 4.1. gr start would I use this also for 180 gr lfn.?

[Rule3]

OK, Thanks.