Loads with Jacketed vs. Cast

[tappedandtagged]

Is it ok to use data for Jacketed Bullets with Hard Cast Bullets?

I've been told by the local reloading shop guy that if I use data for a Jacketed Bullet and load it under a Cast, that I will actually get lower pressures and a bit more FPS out of the load. He said that when loading cast bullets with jacketed data, the only concern is not to push it so fast that the barrel begins to lead.

I want some nice magnum loads for my .357 and a 158 grain LSWC (18 brinell). Preferably with the pound of Unique that I have on hand. Alliant's website says not to go over 6 grains for cast, but says I can use 7.7 grains for the same weight jacketed. Moreover, my Lyman 49 ed. says I can use 8.3 grains for a jacketed 158 grain bullet and has no data for Unique with any of their casts bullets. So far, I've only shot some 12 brinell 158 grain bullets with a max of 5.9 grains of Unique with no leading whatsoever. The loads just don't have much bang and feel like 38 spl.

So, can I up the powder charge up to close to 8 grains as long as I work it up slow and watch for leading? Or should I just stick to data published strictly for cast if I'm loading cast??

 

[OKFC05]

After being at this for awhile, I'm reluctant to handload using general rules or estimates.

If you look at the Lyman loading manual, which has lots of cast bullets, you can see that even similar weight bulets have quite different loading data because of bearing surface, sealing properties, seating depth, etc. Therefore, tested loading data with the actual bullet you intend to use is the intelligent safest way to go about it.

I've had some friends who loaded "by guess and by golly" for years and derided us cautious types, until they blew up a gun.

Loading manuals are cheaper to buy than new guns.

 

[Pisgah]

For once, it seems a gunshop guy has given something like factual advice! While it is always prudent to work up a new load any time any component is changed, data for jacketed bullets can be used for lead bullets of the same weight with the result, as he said, that pressure will be lower and velocity likely a bit faster.

Just do not assume, as some I have known have done, that the opposite is true. Generally, the same manual will show a slightly higher charge weight for a cast bullet versus a jacketed bullet of the same weight, and it is NOT safe to assume you can jack up the jacketed load to meet the lead load.

 

[Alk8944]

There are too many variables to make such a generalization, and these can cause pressures to vary widely when using the same charge with both lead and jacketed bullets.

Depending on the hardness/strength of the cast bullet being used the pressure can be similar or significantly higher when using jacketed data with cast bullets. Often you may never know the difference because you have no way of measuring pressure!

If shooting standard cartridges this is a generally safe practice as there is insufficient impetus from the charge to cause the lead bullet to bump up in the lead of the revolver and cause damage, but when loading high-intensity cartridges such as the Magnums it is safer to use the data specific to the bullet type.

Your source is correct in saying you will get higher velocity with the cast bullet, but when it comes to pressure developed it usually will be just as high, often higher, but rarely significantly less.

When it comes to leading, velocity is not a factor as most believe it to be. Leading is a function of bullet alloy, lubricant and bullet fit. A proper cast bullet can be driven to higher velocity than a jacketed bullet without causing leading, as long as the three noted factors are correct. The reason most see significant leading with cast bullets is they are using commercially cast bullets which usually have insufficient Tin, worthless lubricants that are intended to ship well, and they are often undersized. An undersized bullet allows gasses to blow by the bullet and, very literally, melt the surface of the bullet causing leading.

DO NOT even think about using 8 gr. Unique with a cast bullet. Alliant, and previously Hercules, has never listed more than 6.8 gr. Unique for a pressure of nearly 34,000 PSI. To increase the load to 8.0 gr. will increase pressure by ca. 35%, and that is for single-base powders. Double-base powders, as are all Alliant pistol/shotgun powders, is a completely different matter. If you want/need higher velocity then use 2400, it is the propellant used for initial cartridge development of the .357 Magnum in the early 1930s, and still cannot be improved upon for full power loads for this cartridge.

 

[arjay]

When I was new to reloading I assumed using jacketed data would be safe with lead bullets and it was until I split several cases! Start low and work your way up.

 

[Alk8944]

When I was new to reloading I assumed using jacketed data would be safe with lead bullets and it was until I split several cases! Start low and work your way up.

arjay,

Cases splitting has everything to do with case ductility which is diminished with use. Brass, and all copper based alloys, work hardens and becomes brittle. Pressure is not a factor.

If you have used any polishing product containing ammonia on your brass this will also result in embrittlement and splitting.

 

[alwslate]

Posted by Alk8944.
"DO NOT even think about using 8 gr. Unique with a cast bullet. Alliant, and previously Hercules, has never listed more than 6.8 gr. Unique for a pressure of nearly 34,000 PSI. To increase the load to 8.0 gr. will increase pressure by ca. 35%, and that is for single-base powders. Double-base powders, as are all Alliant pistol/shotgun powders, is a completely different matter. If you want/need higher velocity then use 2400, it is the propellant used for initial cartridge development of the .357 Magnum in the early 1930s, and still cannot be improved upon for full power loads for this cartridge."
Well now my old Lyman cast bullet manual shows a max load of
Unique of 8.0 grs with a 158 gr gas check cast bullet at 35,500 cup.
My old Hercules manual 1-84, shows a max load of Unique of 8.5 grs
with a 158 gr lead bullet at 36,500 cup. Never is a long time and I
think calculating pressure increases based on powder characteristics
like single base or double base might prove dificult. I agree 100%
on the idea of switching to 2400 for full power loads. The money
already spent on the can of Unique is gone, don't worry about it.
Just buy a can of 2400 and load away.

 

[tappedandtagged]

I loaded up some 6.5 grain Unique loads that I intend to test in the morning. I will be getting some 2400 or Accurate No. 9 for more magnum loads. I am leaning toward No. 9 seeing as that company has a lot more data available online for their powders. I've found Alliant's online data to be lacking greatly.

 

[alwslate]

I loaded up some 6.5 grain Unique loads that I intend to test in the morning. I will be getting some 2400 or Accurate No. 9 for more magnum loads. I am leaning toward No. 9 seeing as that company has a lot more data available online for their powders. I've found Alliant's online data to be lacking greatly.

If you're basically interested in one load, a good full power
load with a 158 gr cast bullet, you don't need lots and lots
of information. Around 14.0 grs with magnum primers, my
choice, or up to 15.0 grs with standard primers will suffice
and be within today's pressure standards. I think Alliant has
been taken over by Speer and so the quantity and quality
of their data has declined.

 

[sixshot]

Just because 2 bullets weigh the same doesn't mean you can interchange load data. Seating depth can make a big difference with no other changes, including jacketed vs cast.
8 grs of Unique is an extremely hot load in a 357 maggie!

Dick

 

[Rule3]

I loaded up some 6.5 grain Unique loads that I intend to test in the morning. I will be getting some 2400 or Accurate No. 9 for more magnum loads. I am leaning toward No. 9 seeing as that company has a lot more data available online for their powders. I've found Alliant's online data to be lacking greatly.

Perhaps buy Lymans cast Bullet Manual

 

[fredj338]

I disagree with the premise of lower pressures. No, all data sources will tell you to NOT use jakceted data for equiv lead bullets. Basic rules of powder ingition; all things being equal, pressure = vel. So reducing pressure will reduce vel, NOT increase it. Check loading data for jacketed & identical moly coated jacketed. It requires MORE powder to achieve higher vel not less. Why is that? It's because less friction means less pressure means less vel.
My theory is a lead bullet has higher friction, at least the metals table says so, & larger dia & seals the bore more completely from leaking gases. So it developes a bit more pressure than equiv jacketed, if you can actually find an equiv jacketd bullet shape to compare. The 230gr RN 45 is about the best comparison. Same charge wts, I get about 40fps LESS vel with jacketed. That is telling me slightly higher pressure w/ lead than jacketed to get me higher vel.
As noted, vel & leading rarely have anything to do with one another. No, it's more bullet fit & alloy hardness related to pressures used. Lots of guys out there shooting cast lead bullets @ low rifle vel (1500fps+) w/ little to no leading.

 

[gwpercle]

The late Skeeter Skelton wrote about this load being one of his favorites in 357 mag. and one I liked to shoot in my old model Ruger Blackhawk. The Lyman # 358156 , 156gr. cast SWC with gas check ( gas check eliminates leading but try unchecked bullets if that's what you got ) over 7.5 grs. Unique.

For top end magnum loads go with 2400 , this powder can't be beat in this application.

Don't use bevel base cast bullets in magnum loads, the don't do well at all.

 

[Dashriprock]

DO NOT even think about using 8 gr. Unique with a cast bullet. Alliant, and previously Hercules, has never listed more than 6.8 gr. Unique for a pressure of nearly 34,000 PSI.

Reckon that depends on the cartridge being loaded. Speer #11 lists a 250-gr cast semi-wadcutter .45 Colt load for Blackhawks and Contenders with 10.5 grs. Unique.

 

[BoDog]

pressure curves on powders varry with seating depth, bullet hardness, primer. I have been loading for 40 years, last year I wanted to use a standard power with a 225gr, 44 cal load but the powder wasn't listed, so I called them. The bullistian on their end said well you can start with 20g. and max was 21g. that was with Barnes Copper.

 

[Rule3]

Reckon that depends on the cartridge being loaded. Speer #11 lists a 250-gr cast semi-wadcutter .45 Colt load for Blackhawks and Contenders with 10.5 grs. Unique.

It helps to read the original post as the OP was taking about 357 Mag and 158 gr bullets.

Even though there is "old" data that was published that pushed the use of Unique higher than what is now listed, the advice given is a safer bet for all.

 

[Steve C]

Lead will shoot faster than a jacketed bullet with the same charge weights. Lead has less barrel resistance and slips through easier and therefore is quicker.

The problems with lead can be in leading both if the pressure is too low or too high and if you like to spend hours scrubbing out bores then go ahead an push them as hard as you dare. Careful workup is the best way to avoid all problems though it may take some effort and more time.

If you have absolutely no data for lead a good place to start is a 20% reduction less than the max load for jacketed of the same weight. A 10% reduction from that maximum will usually give your the same as maximum load velocity of the jacketed bullet.

 

[fredj338]

Lead will shoot faster than a jacketed bullet with the same charge weights. Lead has less barrel resistance and slips through easier and therefore is quicker.
.

I still don't buy that. Less resistance or friction means lower pressures/velocity w/ the same charge wts. Yes, lead is more maleable, but that doesn't account for the higher pressures/velocity IMO.

 

[Dashriprock]

It helps to read the original post as the OP was taking about 357 Mag and 158 gr bullets.

Thanks, I noticed that. I also noticed that the response to which I responded said "a" cast bullet. No caliber designation nor weight of projectile. Once generalization begins, we all lose.

But I'm not splitting hairs! Agreed on the safety point you make.

But I wonder: Unique has been around for a mighty long time. While we do know that manufacturers periodically tweak powder makeup, how much can Unique have been changed that would all of a sudden make a 10 gr charge unsafe in a stong action?

I suspect we see these changes in manuals with the progression of time because of the litigious society in which we currently live.

 

[Sal1950]

For various reasons times have changed in relation to recommended max loads over the years.
I have a Lyman 45th edition handbook here, copyright 1970, It lists,

158g Cast bullet /w gas check
Starting load of Unique 4.0g = 680fps
Max Load of Unique 8.0g = 1250fps

You should start at 10% below Max (7.2g) and work your way up watching for pressure signs. Use Caution.
Sal