.38 in a .357 magnum case

Silvanus · April 22, 2008, 01:57 PM

Do you have to adjust your powder charge if you use the longer .357 magnum brass? If so, do I need more or less powder (I suppose more...) ?

I just started reloading, I'm sorry to bother you with my noob questions

Wuchak · April 22, 2008, 02:41 PM

Check the load data for the same projectile on the power maker's site or the free load data books they publish and have at the gun shops. Hodgden's comes to mind. The loads usually overlap with the .357 being able to handle more.

Mikke · April 22, 2008, 03:16 PM

You will need a little more powder in a .357 case to get the same speed. The extra space can be a problem as it's a little more room in the case for the powder to be at, which might give a higher SD/ES, more so if using a small load of a "denser" powder.

And don't use the minimum load for a .38 to load in a .357 case.

dipper · April 22, 2008, 03:59 PM

Buy and READ a good reloading manual--if you purchased the equipment to reload, you should be able to afford a manual to go along with it.
All the manuals I have --and I got some that are over 30 years old---go into reloading in some detail---you need one.

Dipper

SL1 · April 22, 2008, 06:54 PM

Well, the advice to look at the manuals is not necessarily going to answer the question asked. Most manuals now have a max load and a start load that is about 90% of the max load. The premis seems to be that everybody wants hot loads. So, the start load in the 357 mag is usually a higher charge and a higher velocity than the max load in the 38 Special. That does not help the questioner get two loads that will gie the same velocity in the two different cases (using the same powder and bullet).

Some older manuals did have a list of charge weights with velocities for each, spanning several velocity levels. In THOSE manuals, it was possible to find the loads that gave some mid range velocities in both cases. Hornady #4 and Sierra # 2 are examples of manuals with loads for velocity ranges.

Another way to do it would be to use computer programs like "Quickload" or "Load from a Disk" to see ranges of velocities for a range of loads.

Silvanus, if you tell me what powder you are interested in and what velocity you are interested in, I will see if I have any data that will help you.

SL1

dipper · April 22, 2008, 07:22 PM

Well,
It MAY keep him from using to lite a load using the .357 Magnum case---like a low 38 spl. load.
I looked at a few of my manuals and dang nabit, they addressed the pitfalls of using to lite a load with jacketed bullets---I'm sure SL1 YOU know what could happen.
The Question of the OP shows he doesn't have a clue---and that's fine---we all started somewhere.
My advice to him IMHO was fine---he needs to do some more homework and read a good manual--he'll probably have other questions along the way so he may as well educate himself from the get go.
Certainly can't hurt!!

Dipper

Glockmaster84 · April 22, 2008, 07:35 PM

I see alot of people try to make there own reloads and see alot of accidents from people underloading and overloading

clayking · April 22, 2008, 08:10 PM

Quote:

Another way to do it would be to use computer programs like "Quickload" or "Load from a Disk" to see ranges of velocities for a range of loads.

Do you find that either of these programs calculate accurate loads that are stand alone, or do you use them in conjuctions with published loads?
Do they calculate switches like the one asked here, substituting one piece of brass for another.....................ck

joneb · April 22, 2008, 09:19 PM

I would start at the upper end of .38spl data and work up from there ? Some powders will leave lots of extra space in the case, magnum primers may help with velocity spreads if this is a problem. I've loaded .357 mag cases to .38spl +p and + pressures with some very good results.

Silvanus · April 23, 2008, 12:41 AM

Thanks for the advice guys, I really appreciate it. And I do have two manuals, but I supposed they wouldn't answer that particular question. I'll have to look it up.

Quote:

Silvanus, if you tell me what powder you are interested in and what velocity you are interested in, I will see if I have any data that will help you.

Right now I use Accurate No.2

SL1 · April 23, 2008, 09:01 AM

With respect to getting too-lite loads in the 357 Mag case, the question was about how to get the same velocity in the two cases. If you don't go below published 38 Special loads in the 38 Special case, then getting the same velocity in the 357 Mag case will not result in a too-lite load, either. It will actually provide a little more powder, a little more gas, and a little more margin against sticking a bullet in the barrel.

With respect to the computerized load programs, that kind of tradeoff is easily calculated. But, those programs are not that accurate for revolvers.

Heck, even the manual data is not that accurate for predicting revolver velocities. The newest Speer manual has some comparison data for 3 loads in 26 different revolvers. Each revolver got identically loaded cartridges and velocities were measured the same way for each. Just looking at the nine revolvers with 6" barrels, there is a spread of 1237 to 1603 fps for a 110 gr bullet, 1142 to 1417 fps for a 140 gr bullet, and 1002 to 1284 fps for a 158 gr bullet. The only thing you can say about consistency is that the same gun was the fastest with all three loads, and another particular gun was always the slowest. Sooo, if you go to the load data for the 38 Special and see that the test gun was a S&W Model 14 with a 6" barrel, then go to the 357 Mag data and find that the test gun was a S&W Model 19 with a 6" barrel, you can bet that those two guns still won't shoot the same 38 Special cartridge load at the same velocity. So, how do you use THAT 2 sets of data to find the equivalent velocities for two loads for the same 38 Special case that will shoot at the same velocity from your ONE gun? You would need that info before you can very accurately decide how to adjust the load to get the same velocity in the 357 Mag case. But, the manual won't give you that information unless they happen to use the SAME TEST GUN for the 38 Special and 357 Mag data, AND they use the data format that shows several velocities with loads for each with several powders. NONE of my manuals fit that requirement! Anybody else have one that does?

So, all things considered, what I do to answer a qustion like this is a simple calcualtion to keep the ratio of powder charge weight to powder space the same (called the loading density). It is based on the case capacities measured in grains of water and some length measurements of the bullet and the loaded cartridges.

I'll illustrate the method with an example that starts with a max load for the 38 Special from the Accurate Arms 2nd edition manual:

Hornady 158 gr XTP with 4.0 gr of No.2 powder for 16,500 psi and 756 fps from aS&W K-38 with a 8-3/8" barrel.

Using my notes for water capacity measurement of 357 Mag brass fired in MY gun, I have a full-case capacity of 26.1 gr of water for a case that is 1.290" long. A Hornady XTP measured 0.668" long and gave a cartridge OAL of 1.590 when crimped at the cannelure. So, there is 1.290" + 0.668" - 1.590" = 0.388" of bullet inside the 357 Mag case. The volume of the part of the bullet that is inside the case is calculated by multiplying the diameter by itself (i.e., squaring the number) dividing that by 4 and multiplying it by pi (i.e., 3.1416) to get the area of the bullet's base. For a .357" bullet, that is: .357" x .357" / 4 x 3.1416 = 0.100 square inch (a very easy number to remember). So, the area of the base times the length in the case gives 0.100 x 0.388 = 0.0388 cubic inches. We need to subtract that volume from the full-case capacity, but the two volumes were not measured in the same units. We need to convert the cubic inches to an equivalent weight of water. To do that, multiply by 252.8 grains per cubic inch. So, the NET water capacity with the bullet seated is 26.1 - 252.8 x 0.0388 = 16.3 gr of water.

Now, we do the same thing with a 38 Special case. We really should measure the water capacity of the 38 Special casee, because they are not the same internally as a shortened 357 Mag case. But, I don't have that water capacity measurement in my notes, so I am going to cheat a little here and estimate the 38 Special case volume based on shortening the 357 Mag case by the difference in case lengths: 1.290" - 1.155" = 0.135". I'll calculate the volume lost to case shortening the same way I calculated volume lost to bullet seating: 0.100 sq inch x 0.135 inch x 252.8 grains per cubic inch = 3.4 grains of water. So, I now have a net water capacity of 16.3 - 3.4 = 12.9 grains for the 38 Special case.

The ratio of charge weight to NET water for the example 38 Special load is 4 gr powder to 12.9 gr water, or 4 /12.9 = 0.310 in the 38 Special case. To get the same loading density (ratio)in the larger 357 Mag case, I need to multiply the larger case capacity by this ratio: 16.3 x 0.310 = 5.053 gr of No.2 powder.

This should give about the same velocity for both cartridges in the same gun. Using a chronograph would allow further tuning the loads to exactly the same velocity.

I will also acknowledge that the new Speer manual does not list 158 gr jacketed bullet loads for the 38 Special and says the reason is that the velocities are too low so that there is some possibility of a bullet sticking in the barrel. This warning is a new trend. It raises questions about a lot of commercially available ammo as well as a lot of existing handloading data. Speer would not (now) provide a load for #2 powder with a 158 gr bullet in the 38 Special case, although Speer used to do so and most manuals still do. So, if you are using 4.0 grains of No.2 in the 38 Special with 158 grain jacketed bullets (or 5.1 grains in 357 cases) I guess you should be careful that you know each bullet has left your barrel before you pull your trigger again.

At this point, let me caution people who are not mathematically inclinded that they cannot apply the ratio from this example to loads for other bullets. Obvioulsy, bullets of different weights will take up more or less of the case capacity and thus have a different net powder space volume ratio. Even bullets of the same weight can have different seating depths. So, a large hollow point and a full-metal jacket bullet of the same weight will have different lengths, and even 2 JHPs from different manufacturers can have different seating depths due to different cannelure locations. Lead bullets with SWC noses and lube grooves can have much different seating depths than JHPs, and so-on. So, don't fool yourselves with shortcuts that aren't correct.

SL1

Jim Watson · April 23, 2008, 09:17 AM

Once upon a time, you would see a gunzine article about low-end loads in Magnum brass about every year or two. They are too busy putting out puff pieces for the latest tackytickle equipment to bother with instructional material any more.

SL1's calculation and procedure will get you in the ballpark.
Note that Shooting Chrony will sell you a refurbished chronograph for $63.79
http://www.shootingchrony.com/produc...onditioned.htm

CAUTION: Be careful with fast burning powders like AA#2 in large cases like .38 and .357.

The only gun ever blown up on the range here was demolished with Bullseye, probably a double charge. If loading single stage you should block check your charged cases to be sure each and every one contains 1.0 powder load. If progressive, you must form the habit of looking in each and every case as you place the bullet to be seated.

I have seen a barrel bulged with a too-light load and a jacketed softpoint bullet, when the core shot out leaving the jacket in the barrel. The following shot ruined the barrel. Light loads are best done with cast bullets, the Speer warning is right.

dipper · April 23, 2008, 09:49 AM

The OPs original post:

Do you have to adjust your powder charge if you use the longer .357 magnum brass? If so, do I need more or less powder (I suppose more...) ?

SL1:

With respect to getting too-lite loads in the 357 Mag case, the question was about how to get the same velocity in the two cases. If you don't go below published 38 Special loads in the 38 Special case, then getting the same velocity in the 357 Mag case will not result in a too-lite load, either. It will actually provide a little more powder, a little more gas, and a little more margin against sticking a bullet in the barrel.

I see no mention of velocity in the OPs post---he doesn't/didn't have a glue as to potential problems.

Jim Watson:

I have seen a barrel bulged with a too-light load and a jacketed softpoint bullet, when the core shot out leaving the jacket in the barrel. The following shot ruined the barrel. Light loads are best done with cast bullets, the Speer warning is right.

I have seen that too Jim---exactly--again to the OP, get a good manual read it and stick to the loads listed and approach max loads with care and you should be fine.

Dipper

UnderDawgAl · April 23, 2008, 10:19 AM

If I remember correctly, Hornady 6th edition advises that .357 Magnum loads using wadcutters should follow the same load data as for .38 Special. Since I don't have the book right here in front of me, I cannot confirm it with 100% accuracy.

I had the same question as the OP: What charge of Bullseye should I use for loading 148-grain HBWCs in 357 brass? Seems like I settled on around 4.something grains, loaded 5 rounds, and test-fired. I don't have that data right here right now, so I can't tell you the exact load weight. The rounds shot beautifully--accurate and no leading.

WARNING: The above info is from memory. I'll have to confirm it all when I can get back to my notes.

Good discussion.

SL1 · April 23, 2008, 01:31 PM

Dipper,

If you read Silvanus's last post, you will see that he already has TWO manuals. Also, if you read my posts, you will understand that his question is not likely to be answered in ANY manual. So, I don't see the point of telling the guy he doesn't have a clue and should buy a manual! Maybe he does have a clue, but not a chronograph. It would have at least been technically correct to tell him to buy a chronograph, but still not very polite. He already expected he would need more powder, so I would say he does have a clue. He is just asking for a way to figure out how much more powder. Nearly everyone who has loaded 357 Magnums has considered the same question.

The purpose of forums like this is for people to share information, including both how-to's and cautions. I try to provide both where they seem to be appropriate. Silvanus did not say what bullet he was using, but I picked one for an example that used his stated powder. That example comes from the powder manufacturer's manual. Other manuals may choose not to provide similar loads, so I also included a caution.

None of that should reflect on Silvanus. All he said he wants to do is be able to shoot 38 Special power loads using 357 brass. That should never be a problem if he starts with a good 38 Special load and properly adjusts the powder charge to compensate for the extra space in the case, so that the resulting velocity is the same. He never said he wants to use a bad 38 Special load.

SL1

dipper · April 23, 2008, 01:49 PM

SL1,
Respectfully, I don't know what your reading or if your seeing things that aren't there and I'm not trying to be a smart @$$.

The OP asked in his original post if he should use more or less powder when going to the .357 magnum case---in my book, that throws up a red flag that the guy doesn't know the basics---I am not trying to insult him but recognizing that you could have a problem is a good thing.
I have alot of manuals and all the hardcover manuals that I have tell about using lite loads with jacketed bullets and what can happen if you go below suggested loads.
A chronograph isn't going to help him if he sticks the first round in the barrel and pulls the trigger on the second.
If he has a manual as he states, he should have read the part that says " do not deviate from the listed loads" and he wouldn't have had to ask if he should use more or less powder--you know, you look at the powders and read the grains and if he likes, he can cross reference charges between the two.

Again, I am not seeing the words you are in the posts.

Dipper

Silvanus · April 23, 2008, 02:11 PM

Again, thank you for your comments.

I forgot to give you the details about the loads I was loading the first time.

I used .38 special cases with 158 grs TMJ FP bullets over 4.0 grs of Accurate No.2. That's the recommended max load from their manual. They work rather good, but I have way more (1000+) .357 magnum cases than .38 ones. What I tried to find out in this thread is simply if I have to use a little more powder in the larger magnum case. I don't want a particularly "light" target load (I use WC rounds for that). I just need a "normal" or +p .38 special load. It mustn't be the same as with the .38 special case. I just want to make sure it works. And it's no problem if it's a little on the hot side, I will use the rounds in .357 magnum guns only. So I would be more concerned about too weak loads than strong ones. But I didn't want to experiment with the powder charge myself, because (like some people rightfully suspected already

) I don't know that much about reloading yet.

If you guys can recommend a good reloading manual I would be happy to take a look at that too. The ones I have are both German, but regarding firearms, I'm used to mostly English expressions and that language in general, so I'll probably buy an American book soon.

SL1 · April 23, 2008, 02:37 PM

Jim Watson,

I am curious about what type of bullet caused the core separation that you witnessed. Was it one of the old Speer "3/4 - jacket SWC" designs that have a straight jacket cup that does not bend over the nose at all? There have been warnings for decades about that particular bullet type having the core separate and leave the cup in the barrel when shot at too low power.

But, the warnings about other bullet types seem rather recent. Speer claims that its "Uni-cor" design cannot experience jacket separation because the jacket is bonded (by plating) to the core. Their warnings now concern sticking the whole bullet in the bore with light loads. That seems much less likely to me.

Also, shooting the core out of the jacket in a bullet like the XTP, with the jacket wrapped around the nose and into the cavity, seems a lot less likely than losing the jacket on the old Speer design. But, I guess it might happen. So, I am wondering if what you witnessed was with one of the newer jacketed bullets.

On a side-note, if Silvanus is using FMJ or TMJ bullets, I don't think he is going to have any problem with jacket separation, but there is still the issue of sticking the whole bullet in the bore that Speer cautions about.

SL1

GP100man · April 23, 2008, 09:05 PM

look under cowboy loads there reduced loads ,not bunny pooters though.

i shoot homecast alloyed boolits& have for some time now .
the jacket thing mostly happens with a "half" jacket designs & most manufactures don`t carry em nomo, i`m also wary of bullet designs that have open bases & a hollw point.

GP100man##

mattamuskeet · April 24, 2008, 07:26 PM

No, you don't have to use more powder. I use 4.7 grains of unique in 357 mag cases and the speer manual goes down to 4.0 grains for lead bullets(rifle data). The only reason they enlongated the case was to prevent its use in 38 guns that couldn't handle the pressure; not to hold more powder. If you are reloading for 357 firearms, just stick with 357 brass anyway. I don't see any advantage in loading 38 rounds for a 357 unless you got a butt load of brass for free or something.

April 22, 2008, 01:57 PM	#1
Silvanus Senior Member Join Date: July 23, 2005 Location: Luxembourg Posts: 1,324	.38 in a .357 magnum case Do you have to adjust your powder charge if you use the longer .357 magnum brass? If so, do I need more or less powder (I suppose more...) ? I just started reloading, I'm sorry to bother you with my noob questions

April 22, 2008, 07:35 PM	#7
Glockmaster84 Junior Member Join Date: April 22, 2008 Location: Glen arm MD Posts: 1	if you dont know what your doing stop I see alot of people try to make there own reloads and see alot of accidents from people underloading and overloading

April 23, 2008, 09:49 AM	#13
dipper Senior Member Join Date: April 6, 2008 Posts: 895	loads The OPs original post: Do you have to adjust your powder charge if you use the longer .357 magnum brass? If so, do I need more or less powder (I suppose more...) ? SL1: With respect to getting too-lite loads in the 357 Mag case, the question was about how to get the same velocity in the two cases. If you don't go below published 38 Special loads in the 38 Special case, then getting the same velocity in the 357 Mag case will not result in a too-lite load, either. It will actually provide a little more powder, a little more gas, and a little more margin against sticking a bullet in the barrel. I see no mention of velocity in the OPs post---he doesn't/didn't have a glue as to potential problems. Jim Watson: I have seen a barrel bulged with a too-light load and a jacketed softpoint bullet, when the core shot out leaving the jacket in the barrel. The following shot ruined the barrel. Light loads are best done with cast bullets, the Speer warning is right. I have seen that too Jim---exactly--again to the OP, get a good manual read it and stick to the loads listed and approach max loads with care and you should be fine. Dipper

April 23, 2008, 02:11 PM	#17
Silvanus Senior Member Join Date: July 23, 2005 Location: Luxembourg Posts: 1,324	Again, thank you for your comments. I forgot to give you the details about the loads I was loading the first time. I used .38 special cases with 158 grs TMJ FP bullets over 4.0 grs of Accurate No.2. That's the recommended max load from their manual. They work rather good, but I have way more (1000+) .357 magnum cases than .38 ones. What I tried to find out in this thread is simply if I have to use a little more powder in the larger magnum case. I don't want a particularly "light" target load (I use WC rounds for that). I just need a "normal" or +p .38 special load. It mustn't be the same as with the .38 special case. I just want to make sure it works. And it's no problem if it's a little on the hot side, I will use the rounds in .357 magnum guns only. So I would be more concerned about too weak loads than strong ones. But I didn't want to experiment with the powder charge myself, because (like some people rightfully suspected already) I don't know that much about reloading yet. If you guys can recommend a good reloading manual I would be happy to take a look at that too. The ones I have are both German, but regarding firearms, I'm used to mostly English expressions and that language in general, so I'll probably buy an American book soon. Last edited by Silvanus; April 23, 2008 at 02:54 PM.

April 23, 2008, 09:05 PM	#19
GP100man Senior Member Join Date: August 1, 2007 Location: Tabor City , NC. Posts: 1,969	cowboy stuff look under cowboy loads there reduced loads ,not bunny pooters though. i shoot homecast alloyed boolits& have for some time now . the jacket thing mostly happens with a "half" jacket designs & most manufactures don`t carry em nomo, i`m also wary of bullet designs that have open bases & a hollw point. GP100man##

April 22, 2008, 02:41 PM	#2
Wuchak Senior Member Join Date: June 1, 2007 Location: Shawnee, KS Posts: 1,093	Check the load data for the same projectile on the power maker's site or the free load data books they publish and have at the gun shops. Hodgden's comes to mind. The loads usually overlap with the .357 being able to handle more.

April 22, 2008, 03:16 PM	#3
Mikke Senior Member Join Date: May 30, 2000 Location: Ume?, Sweden Posts: 154	You will need a little more powder in a .357 case to get the same speed. The extra space can be a problem as it's a little more room in the case for the powder to be at, which might give a higher SD/ES, more so if using a small load of a "denser" powder. And don't use the minimum load for a .38 to load in a .357 case.

April 22, 2008, 03:59 PM	#4
dipper Senior Member Join Date: April 6, 2008 Posts: 895	Buy and READ a good reloading manual--if you purchased the equipment to reload, you should be able to afford a manual to go along with it. All the manuals I have --and I got some that are over 30 years old---go into reloading in some detail---you need one. Dipper

April 22, 2008, 06:54 PM	#5
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Well, the advice to look at the manuals is not necessarily going to answer the question asked. Most manuals now have a max load and a start load that is about 90% of the max load. The premis seems to be that everybody wants hot loads. So, the start load in the 357 mag is usually a higher charge and a higher velocity than the max load in the 38 Special. That does not help the questioner get two loads that will gie the same velocity in the two different cases (using the same powder and bullet). Some older manuals did have a list of charge weights with velocities for each, spanning several velocity levels. In THOSE manuals, it was possible to find the loads that gave some mid range velocities in both cases. Hornady #4 and Sierra # 2 are examples of manuals with loads for velocity ranges. Another way to do it would be to use computer programs like "Quickload" or "Load from a Disk" to see ranges of velocities for a range of loads. Silvanus, if you tell me what powder you are interested in and what velocity you are interested in, I will see if I have any data that will help you. SL1

April 22, 2008, 07:22 PM	#6
dipper Senior Member Join Date: April 6, 2008 Posts: 895	Well, It MAY keep him from using to lite a load using the .357 Magnum case---like a low 38 spl. load. I looked at a few of my manuals and dang nabit, they addressed the pitfalls of using to lite a load with jacketed bullets---I'm sure SL1 YOU know what could happen. The Question of the OP shows he doesn't have a clue---and that's fine---we all started somewhere. My advice to him IMHO was fine---he needs to do some more homework and read a good manual--he'll probably have other questions along the way so he may as well educate himself from the get go. Certainly can't hurt!! Dipper

April 22, 2008, 09:19 PM	#9
joneb Senior Member Join Date: December 10, 2005 Location: Central , OR Posts: 1,888	I would start at the upper end of .38spl data and work up from there ? Some powders will leave lots of extra space in the case, magnum primers may help with velocity spreads if this is a problem. I've loaded .357 mag cases to .38spl +p and + pressures with some very good results.

April 23, 2008, 09:01 AM	#11
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	With respect to getting too-lite loads in the 357 Mag case, the question was about how to get the same velocity in the two cases. If you don't go below published 38 Special loads in the 38 Special case, then getting the same velocity in the 357 Mag case will not result in a too-lite load, either. It will actually provide a little more powder, a little more gas, and a little more margin against sticking a bullet in the barrel. With respect to the computerized load programs, that kind of tradeoff is easily calculated. But, those programs are not that accurate for revolvers. Heck, even the manual data is not that accurate for predicting revolver velocities. The newest Speer manual has some comparison data for 3 loads in 26 different revolvers. Each revolver got identically loaded cartridges and velocities were measured the same way for each. Just looking at the nine revolvers with 6" barrels, there is a spread of 1237 to 1603 fps for a 110 gr bullet, 1142 to 1417 fps for a 140 gr bullet, and 1002 to 1284 fps for a 158 gr bullet. The only thing you can say about consistency is that the same gun was the fastest with all three loads, and another particular gun was always the slowest. Sooo, if you go to the load data for the 38 Special and see that the test gun was a S&W Model 14 with a 6" barrel, then go to the 357 Mag data and find that the test gun was a S&W Model 19 with a 6" barrel, you can bet that those two guns still won't shoot the same 38 Special cartridge load at the same velocity. So, how do you use THAT 2 sets of data to find the equivalent velocities for two loads for the same 38 Special case that will shoot at the same velocity from your ONE gun? You would need that info before you can very accurately decide how to adjust the load to get the same velocity in the 357 Mag case. But, the manual won't give you that information unless they happen to use the SAME TEST GUN for the 38 Special and 357 Mag data, AND they use the data format that shows several velocities with loads for each with several powders. NONE of my manuals fit that requirement! Anybody else have one that does? So, all things considered, what I do to answer a qustion like this is a simple calcualtion to keep the ratio of powder charge weight to powder space the same (called the loading density). It is based on the case capacities measured in grains of water and some length measurements of the bullet and the loaded cartridges. I'll illustrate the method with an example that starts with a max load for the 38 Special from the Accurate Arms 2nd edition manual: Hornady 158 gr XTP with 4.0 gr of No.2 powder for 16,500 psi and 756 fps from aS&W K-38 with a 8-3/8" barrel. Using my notes for water capacity measurement of 357 Mag brass fired in MY gun, I have a full-case capacity of 26.1 gr of water for a case that is 1.290" long. A Hornady XTP measured 0.668" long and gave a cartridge OAL of 1.590 when crimped at the cannelure. So, there is 1.290" + 0.668" - 1.590" = 0.388" of bullet inside the 357 Mag case. The volume of the part of the bullet that is inside the case is calculated by multiplying the diameter by itself (i.e., squaring the number) dividing that by 4 and multiplying it by pi (i.e., 3.1416) to get the area of the bullet's base. For a .357" bullet, that is: .357" x .357" / 4 x 3.1416 = 0.100 square inch (a very easy number to remember). So, the area of the base times the length in the case gives 0.100 x 0.388 = 0.0388 cubic inches. We need to subtract that volume from the full-case capacity, but the two volumes were not measured in the same units. We need to convert the cubic inches to an equivalent weight of water. To do that, multiply by 252.8 grains per cubic inch. So, the NET water capacity with the bullet seated is 26.1 - 252.8 x 0.0388 = 16.3 gr of water. Now, we do the same thing with a 38 Special case. We really should measure the water capacity of the 38 Special casee, because they are not the same internally as a shortened 357 Mag case. But, I don't have that water capacity measurement in my notes, so I am going to cheat a little here and estimate the 38 Special case volume based on shortening the 357 Mag case by the difference in case lengths: 1.290" - 1.155" = 0.135". I'll calculate the volume lost to case shortening the same way I calculated volume lost to bullet seating: 0.100 sq inch x 0.135 inch x 252.8 grains per cubic inch = 3.4 grains of water. So, I now have a net water capacity of 16.3 - 3.4 = 12.9 grains for the 38 Special case. The ratio of charge weight to NET water for the example 38 Special load is 4 gr powder to 12.9 gr water, or 4 /12.9 = 0.310 in the 38 Special case. To get the same loading density (ratio)in the larger 357 Mag case, I need to multiply the larger case capacity by this ratio: 16.3 x 0.310 = 5.053 gr of No.2 powder. This should give about the same velocity for both cartridges in the same gun. Using a chronograph would allow further tuning the loads to exactly the same velocity. I will also acknowledge that the new Speer manual does not list 158 gr jacketed bullet loads for the 38 Special and says the reason is that the velocities are too low so that there is some possibility of a bullet sticking in the barrel. This warning is a new trend. It raises questions about a lot of commercially available ammo as well as a lot of existing handloading data. Speer would not (now) provide a load for #2 powder with a 158 gr bullet in the 38 Special case, although Speer used to do so and most manuals still do. So, if you are using 4.0 grains of No.2 in the 38 Special with 158 grain jacketed bullets (or 5.1 grains in 357 cases) I guess you should be careful that you know each bullet has left your barrel before you pull your trigger again. At this point, let me caution people who are not mathematically inclinded that they cannot apply the ratio from this example to loads for other bullets. Obvioulsy, bullets of different weights will take up more or less of the case capacity and thus have a different net powder space volume ratio. Even bullets of the same weight can have different seating depths. So, a large hollow point and a full-metal jacket bullet of the same weight will have different lengths, and even 2 JHPs from different manufacturers can have different seating depths due to different cannelure locations. Lead bullets with SWC noses and lube grooves can have much different seating depths than JHPs, and so-on. So, don't fool yourselves with shortcuts that aren't correct. SL1

April 23, 2008, 09:17 AM	#12
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,535	Once upon a time, you would see a gunzine article about low-end loads in Magnum brass about every year or two. They are too busy putting out puff pieces for the latest tackytickle equipment to bother with instructional material any more. SL1's calculation and procedure will get you in the ballpark. Note that Shooting Chrony will sell you a refurbished chronograph for $63.79 http://www.shootingchrony.com/produc...onditioned.htm CAUTION: Be careful with fast burning powders like AA#2 in large cases like .38 and .357. The only gun ever blown up on the range here was demolished with Bullseye, probably a double charge. If loading single stage you should block check your charged cases to be sure each and every one contains 1.0 powder load. If progressive, you must form the habit of looking in each and every case as you place the bullet to be seated. I have seen a barrel bulged with a too-light load and a jacketed softpoint bullet, when the core shot out leaving the jacket in the barrel. The following shot ruined the barrel. Light loads are best done with cast bullets, the Speer warning is right.

April 23, 2008, 10:19 AM	#14
UnderDawgAl Member Join Date: October 27, 2004 Location: VA Posts: 37	If I remember correctly, Hornady 6th edition advises that .357 Magnum loads using wadcutters should follow the same load data as for .38 Special. Since I don't have the book right here in front of me, I cannot confirm it with 100% accuracy. I had the same question as the OP: What charge of Bullseye should I use for loading 148-grain HBWCs in 357 brass? Seems like I settled on around 4.something grains, loaded 5 rounds, and test-fired. I don't have that data right here right now, so I can't tell you the exact load weight. The rounds shot beautifully--accurate and no leading. WARNING: The above info is from memory. I'll have to confirm it all when I can get back to my notes. Good discussion.

April 23, 2008, 01:31 PM	#15
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Dipper, If you read Silvanus's last post, you will see that he already has TWO manuals. Also, if you read my posts, you will understand that his question is not likely to be answered in ANY manual. So, I don't see the point of telling the guy he doesn't have a clue and should buy a manual! Maybe he does have a clue, but not a chronograph. It would have at least been technically correct to tell him to buy a chronograph, but still not very polite. He already expected he would need more powder, so I would say he does have a clue. He is just asking for a way to figure out how much more powder. Nearly everyone who has loaded 357 Magnums has considered the same question. The purpose of forums like this is for people to share information, including both how-to's and cautions. I try to provide both where they seem to be appropriate. Silvanus did not say what bullet he was using, but I picked one for an example that used his stated powder. That example comes from the powder manufacturer's manual. Other manuals may choose not to provide similar loads, so I also included a caution. None of that should reflect on Silvanus. All he said he wants to do is be able to shoot 38 Special power loads using 357 brass. That should never be a problem if he starts with a good 38 Special load and properly adjusts the powder charge to compensate for the extra space in the case, so that the resulting velocity is the same. He never said he wants to use a bad 38 Special load. SL1

April 23, 2008, 01:49 PM	#16
dipper Senior Member Join Date: April 6, 2008 Posts: 895	SL1, Respectfully, I don't know what your reading or if your seeing things that aren't there and I'm not trying to be a smart @$$. The OP asked in his original post if he should use more or less powder when going to the .357 magnum case---in my book, that throws up a red flag that the guy doesn't know the basics---I am not trying to insult him but recognizing that you could have a problem is a good thing. I have alot of manuals and all the hardcover manuals that I have tell about using lite loads with jacketed bullets and what can happen if you go below suggested loads. A chronograph isn't going to help him if he sticks the first round in the barrel and pulls the trigger on the second. If he has a manual as he states, he should have read the part that says " do not deviate from the listed loads" and he wouldn't have had to ask if he should use more or less powder--you know, you look at the powders and read the grains and if he likes, he can cross reference charges between the two. Again, I am not seeing the words you are in the posts. Dipper

April 23, 2008, 02:37 PM	#18
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Jim Watson, I am curious about what type of bullet caused the core separation that you witnessed. Was it one of the old Speer "3/4 - jacket SWC" designs that have a straight jacket cup that does not bend over the nose at all? There have been warnings for decades about that particular bullet type having the core separate and leave the cup in the barrel when shot at too low power. But, the warnings about other bullet types seem rather recent. Speer claims that its "Uni-cor" design cannot experience jacket separation because the jacket is bonded (by plating) to the core. Their warnings now concern sticking the whole bullet in the bore with light loads. That seems much less likely to me. Also, shooting the core out of the jacket in a bullet like the XTP, with the jacket wrapped around the nose and into the cavity, seems a lot less likely than losing the jacket on the old Speer design. But, I guess it might happen. So, I am wondering if what you witnessed was with one of the newer jacketed bullets. On a side-note, if Silvanus is using FMJ or TMJ bullets, I don't think he is going to have any problem with jacket separation, but there is still the issue of sticking the whole bullet in the bore that Speer cautions about. SL1

April 24, 2008, 07:26 PM	#20
mattamuskeet Member Join Date: April 7, 2008 Location: North Carolina Posts: 99	No, you don't have to use more powder. I use 4.7 grains of unique in 357 mag cases and the speer manual goes down to 4.0 grains for lead bullets(rifle data). The only reason they enlongated the case was to prevent its use in 38 guns that couldn't handle the pressure; not to hold more powder. If you are reloading for 357 firearms, just stick with 357 brass anyway. I don't see any advantage in loading 38 rounds for a 357 unless you got a butt load of brass for free or something.